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/home/tahkoom/public_html/wp-includes/sodium_compat/src/Core/Curve25519.php
<?php

if (class_exists('ParagonIE_Sodium_Core_Curve25519', false)) {
    return;
}

/**
 * Class ParagonIE_Sodium_Core_Curve25519
 *
 * Implements Curve25519 core functions
 *
 * Based on the ref10 curve25519 code provided by libsodium
 *
 * @ref https://github.com/jedisct1/libsodium/blob/master/src/libsodium/crypto_core/curve25519/ref10/curve25519_ref10.c
 */
abstract class ParagonIE_Sodium_Core_Curve25519 extends ParagonIE_Sodium_Core_Curve25519_H
{
    /**
     * Get a field element of size 10 with a value of 0
     *
     * @internal You should not use this directly from another application
     *
     * @return ParagonIE_Sodium_Core_Curve25519_Fe
     */
    public static function fe_0()
    {
        return ParagonIE_Sodium_Core_Curve25519_Fe::fromArray(
            array(0, 0, 0, 0, 0, 0, 0, 0, 0, 0)
        );
    }

    /**
     * Get a field element of size 10 with a value of 1
     *
     * @internal You should not use this directly from another application
     *
     * @return ParagonIE_Sodium_Core_Curve25519_Fe
     */
    public static function fe_1()
    {
        return ParagonIE_Sodium_Core_Curve25519_Fe::fromArray(
            array(1, 0, 0, 0, 0, 0, 0, 0, 0, 0)
        );
    }

    /**
     * Add two field elements.
     *
     * @internal You should not use this directly from another application
     *
     * @param ParagonIE_Sodium_Core_Curve25519_Fe $f
     * @param ParagonIE_Sodium_Core_Curve25519_Fe $g
     * @return ParagonIE_Sodium_Core_Curve25519_Fe
     * @psalm-suppress MixedAssignment
     * @psalm-suppress MixedOperand
     */
    public static function fe_add(
        ParagonIE_Sodium_Core_Curve25519_Fe $f,
        ParagonIE_Sodium_Core_Curve25519_Fe $g
    ) {
        /** @var array<int, int> $arr */
        $arr = array();
        for ($i = 0; $i < 10; ++$i) {
            $arr[$i] = (int) ($f[$i] + $g[$i]);
        }
        return ParagonIE_Sodium_Core_Curve25519_Fe::fromArray($arr);
    }

    /**
     * Constant-time conditional move.
     *
     * @internal You should not use this directly from another application
     *
     * @param ParagonIE_Sodium_Core_Curve25519_Fe $f
     * @param ParagonIE_Sodium_Core_Curve25519_Fe $g
     * @param int $b
     * @return ParagonIE_Sodium_Core_Curve25519_Fe
     * @psalm-suppress MixedAssignment
     */
    public static function fe_cmov(
        ParagonIE_Sodium_Core_Curve25519_Fe $f,
        ParagonIE_Sodium_Core_Curve25519_Fe $g,
        $b = 0
    ) {
        /** @var array<int, int> $h */
        $h = array();
        $b *= -1;
        for ($i = 0; $i < 10; ++$i) {
            $x = (($f[$i] ^ $g[$i]) & $b);
            $h[$i] = ($f[$i]) ^ $x;
        }
        return ParagonIE_Sodium_Core_Curve25519_Fe::fromArray($h);
    }

    /**
     * Create a copy of a field element.
     *
     * @internal You should not use this directly from another application
     *
     * @param ParagonIE_Sodium_Core_Curve25519_Fe $f
     * @return ParagonIE_Sodium_Core_Curve25519_Fe
     */
    public static function fe_copy(ParagonIE_Sodium_Core_Curve25519_Fe $f)
    {
        $h = clone $f;
        return $h;
    }

    /**
     * Give: 32-byte string.
     * Receive: A field element object to use for internal calculations.
     *
     * @internal You should not use this directly from another application
     *
     * @param string $s
     * @return ParagonIE_Sodium_Core_Curve25519_Fe
     * @throws RangeException
     * @throws TypeError
     */
    public static function fe_frombytes($s)
    {
        if (self::strlen($s) !== 32) {
            throw new RangeException('Expected a 32-byte string.');
        }
        $h0 = self::load_4($s);
        $h1 = self::load_3(self::substr($s, 4, 3)) << 6;
        $h2 = self::load_3(self::substr($s, 7, 3)) << 5;
        $h3 = self::load_3(self::substr($s, 10, 3)) << 3;
        $h4 = self::load_3(self::substr($s, 13, 3)) << 2;
        $h5 = self::load_4(self::substr($s, 16, 4));
        $h6 = self::load_3(self::substr($s, 20, 3)) << 7;
        $h7 = self::load_3(self::substr($s, 23, 3)) << 5;
        $h8 = self::load_3(self::substr($s, 26, 3)) << 4;
        $h9 = (self::load_3(self::substr($s, 29, 3)) & 8388607) << 2;

        $carry9 = ($h9 + (1 << 24)) >> 25;
        $h0 += self::mul($carry9, 19, 5);
        $h9 -= $carry9 << 25;
        $carry1 = ($h1 + (1 << 24)) >> 25;
        $h2 += $carry1;
        $h1 -= $carry1 << 25;
        $carry3 = ($h3 + (1 << 24)) >> 25;
        $h4 += $carry3;
        $h3 -= $carry3 << 25;
        $carry5 = ($h5 + (1 << 24)) >> 25;
        $h6 += $carry5;
        $h5 -= $carry5 << 25;
        $carry7 = ($h7 + (1 << 24)) >> 25;
        $h8 += $carry7;
        $h7 -= $carry7 << 25;

        $carry0 = ($h0 + (1 << 25)) >> 26;
        $h1 += $carry0;
        $h0 -= $carry0 << 26;
        $carry2 = ($h2 + (1 << 25)) >> 26;
        $h3 += $carry2;
        $h2 -= $carry2 << 26;
        $carry4 = ($h4 + (1 << 25)) >> 26;
        $h5 += $carry4;
        $h4 -= $carry4 << 26;
        $carry6 = ($h6 + (1 << 25)) >> 26;
        $h7 += $carry6;
        $h6 -= $carry6 << 26;
        $carry8 = ($h8 + (1 << 25)) >> 26;
        $h9 += $carry8;
        $h8 -= $carry8 << 26;

        return ParagonIE_Sodium_Core_Curve25519_Fe::fromArray(
            array(
                (int) $h0,
                (int) $h1,
                (int) $h2,
                (int) $h3,
                (int) $h4,
                (int) $h5,
                (int) $h6,
                (int) $h7,
                (int) $h8,
                (int) $h9
            )
        );
    }

    /**
     * Convert a field element to a byte string.
     *
     * @internal You should not use this directly from another application
     *
     * @param ParagonIE_Sodium_Core_Curve25519_Fe $h
     * @return string
     */
    public static function fe_tobytes(ParagonIE_Sodium_Core_Curve25519_Fe $h)
    {
        $h0 = (int) $h[0];
        $h1 = (int) $h[1];
        $h2 = (int) $h[2];
        $h3 = (int) $h[3];
        $h4 = (int) $h[4];
        $h5 = (int) $h[5];
        $h6 = (int) $h[6];
        $h7 = (int) $h[7];
        $h8 = (int) $h[8];
        $h9 = (int) $h[9];

        $q = (self::mul($h9, 19, 5) + (1 << 24)) >> 25;
        $q = ($h0 + $q) >> 26;
        $q = ($h1 + $q) >> 25;
        $q = ($h2 + $q) >> 26;
        $q = ($h3 + $q) >> 25;
        $q = ($h4 + $q) >> 26;
        $q = ($h5 + $q) >> 25;
        $q = ($h6 + $q) >> 26;
        $q = ($h7 + $q) >> 25;
        $q = ($h8 + $q) >> 26;
        $q = ($h9 + $q) >> 25;

        $h0 += self::mul($q, 19, 5);

        $carry0 = $h0 >> 26;
        $h1 += $carry0;
        $h0 -= $carry0 << 26;
        $carry1 = $h1 >> 25;
        $h2 += $carry1;
        $h1 -= $carry1 << 25;
        $carry2 = $h2 >> 26;
        $h3 += $carry2;
        $h2 -= $carry2 << 26;
        $carry3 = $h3 >> 25;
        $h4 += $carry3;
        $h3 -= $carry3 << 25;
        $carry4 = $h4 >> 26;
        $h5 += $carry4;
        $h4 -= $carry4 << 26;
        $carry5 = $h5 >> 25;
        $h6 += $carry5;
        $h5 -= $carry5 << 25;
        $carry6 = $h6 >> 26;
        $h7 += $carry6;
        $h6 -= $carry6 << 26;
        $carry7 = $h7 >> 25;
        $h8 += $carry7;
        $h7 -= $carry7 << 25;
        $carry8 = $h8 >> 26;
        $h9 += $carry8;
        $h8 -= $carry8 << 26;
        $carry9 = $h9 >> 25;
        $h9 -= $carry9 << 25;

        /**
         * @var array<int, int>
         */
        $s = array(
            (int) (($h0 >> 0) & 0xff),
            (int) (($h0 >> 8) & 0xff),
            (int) (($h0 >> 16) & 0xff),
            (int) ((($h0 >> 24) | ($h1 << 2)) & 0xff),
            (int) (($h1 >> 6) & 0xff),
            (int) (($h1 >> 14) & 0xff),
            (int) ((($h1 >> 22) | ($h2 << 3)) & 0xff),
            (int) (($h2 >> 5) & 0xff),
            (int) (($h2 >> 13) & 0xff),
            (int) ((($h2 >> 21) | ($h3 << 5)) & 0xff),
            (int) (($h3 >> 3) & 0xff),
            (int) (($h3 >> 11) & 0xff),
            (int) ((($h3 >> 19) | ($h4 << 6)) & 0xff),
            (int) (($h4 >> 2) & 0xff),
            (int) (($h4 >> 10) & 0xff),
            (int) (($h4 >> 18) & 0xff),
            (int) (($h5 >> 0) & 0xff),
            (int) (($h5 >> 8) & 0xff),
            (int) (($h5 >> 16) & 0xff),
            (int) ((($h5 >> 24) | ($h6 << 1)) & 0xff),
            (int) (($h6 >> 7) & 0xff),
            (int) (($h6 >> 15) & 0xff),
            (int) ((($h6 >> 23) | ($h7 << 3)) & 0xff),
            (int) (($h7 >> 5) & 0xff),
            (int) (($h7 >> 13) & 0xff),
            (int) ((($h7 >> 21) | ($h8 << 4)) & 0xff),
            (int) (($h8 >> 4) & 0xff),
            (int) (($h8 >> 12) & 0xff),
            (int) ((($h8 >> 20) | ($h9 << 6)) & 0xff),
            (int) (($h9 >> 2) & 0xff),
            (int) (($h9 >> 10) & 0xff),
            (int) (($h9 >> 18) & 0xff)
        );
        return self::intArrayToString($s);
    }

    /**
     * Is a field element negative? (1 = yes, 0 = no. Used in calculations.)
     *
     * @internal You should not use this directly from another application
     *
     * @param ParagonIE_Sodium_Core_Curve25519_Fe $f
     * @return int
     * @throws SodiumException
     * @throws TypeError
     */
    public static function fe_isnegative(ParagonIE_Sodium_Core_Curve25519_Fe $f)
    {
        $str = self::fe_tobytes($f);
        return (int) (self::chrToInt($str[0]) & 1);
    }

    /**
     * Returns 0 if this field element results in all NUL bytes.
     *
     * @internal You should not use this directly from another application
     *
     * @param ParagonIE_Sodium_Core_Curve25519_Fe $f
     * @return bool
     * @throws SodiumException
     * @throws TypeError
     */
    public static function fe_isnonzero(ParagonIE_Sodium_Core_Curve25519_Fe $f)
    {
        static $zero;
        if ($zero === null) {
            $zero = str_repeat("\x00", 32);
        }
        /** @var string $zero */
        /** @var string $str */
        $str = self::fe_tobytes($f);
        return !self::verify_32($str, (string) $zero);
    }

    /**
     * Multiply two field elements
     *
     * h = f * g
     *
     * @internal You should not use this directly from another application
     *
     * @security Is multiplication a source of timing leaks? If so, can we do
     *           anything to prevent that from happening?
     *
     * @param ParagonIE_Sodium_Core_Curve25519_Fe $f
     * @param ParagonIE_Sodium_Core_Curve25519_Fe $g
     * @return ParagonIE_Sodium_Core_Curve25519_Fe
     */
    public static function fe_mul(
        ParagonIE_Sodium_Core_Curve25519_Fe $f,
        ParagonIE_Sodium_Core_Curve25519_Fe $g
    ) {
        // Ensure limbs aren't oversized.
        $f = self::fe_normalize($f);
        $g = self::fe_normalize($g);
        $f0 = $f[0];
        $f1 = $f[1];
        $f2 = $f[2];
        $f3 = $f[3];
        $f4 = $f[4];
        $f5 = $f[5];
        $f6 = $f[6];
        $f7 = $f[7];
        $f8 = $f[8];
        $f9 = $f[9];
        $g0 = $g[0];
        $g1 = $g[1];
        $g2 = $g[2];
        $g3 = $g[3];
        $g4 = $g[4];
        $g5 = $g[5];
        $g6 = $g[6];
        $g7 = $g[7];
        $g8 = $g[8];
        $g9 = $g[9];
        $g1_19 = self::mul($g1, 19, 5);
        $g2_19 = self::mul($g2, 19, 5);
        $g3_19 = self::mul($g3, 19, 5);
        $g4_19 = self::mul($g4, 19, 5);
        $g5_19 = self::mul($g5, 19, 5);
        $g6_19 = self::mul($g6, 19, 5);
        $g7_19 = self::mul($g7, 19, 5);
        $g8_19 = self::mul($g8, 19, 5);
        $g9_19 = self::mul($g9, 19, 5);
        $f1_2 = $f1 << 1;
        $f3_2 = $f3 << 1;
        $f5_2 = $f5 << 1;
        $f7_2 = $f7 << 1;
        $f9_2 = $f9 << 1;
        $f0g0    = self::mul($f0,    $g0, 26);
        $f0g1    = self::mul($f0,    $g1, 25);
        $f0g2    = self::mul($f0,    $g2, 26);
        $f0g3    = self::mul($f0,    $g3, 25);
        $f0g4    = self::mul($f0,    $g4, 26);
        $f0g5    = self::mul($f0,    $g5, 25);
        $f0g6    = self::mul($f0,    $g6, 26);
        $f0g7    = self::mul($f0,    $g7, 25);
        $f0g8    = self::mul($f0,    $g8, 26);
        $f0g9    = self::mul($f0,    $g9, 26);
        $f1g0    = self::mul($f1,    $g0, 26);
        $f1g1_2  = self::mul($f1_2,  $g1, 25);
        $f1g2    = self::mul($f1,    $g2, 26);
        $f1g3_2  = self::mul($f1_2,  $g3, 25);
        $f1g4    = self::mul($f1,    $g4, 26);
        $f1g5_2  = self::mul($f1_2,  $g5, 25);
        $f1g6    = self::mul($f1,    $g6, 26);
        $f1g7_2  = self::mul($f1_2,  $g7, 25);
        $f1g8    = self::mul($f1,    $g8, 26);
        $f1g9_38 = self::mul($g9_19, $f1_2, 26);
        $f2g0    = self::mul($f2,    $g0, 26);
        $f2g1    = self::mul($f2,    $g1, 25);
        $f2g2    = self::mul($f2,    $g2, 26);
        $f2g3    = self::mul($f2,    $g3, 25);
        $f2g4    = self::mul($f2,    $g4, 26);
        $f2g5    = self::mul($f2,    $g5, 25);
        $f2g6    = self::mul($f2,    $g6, 26);
        $f2g7    = self::mul($f2,    $g7, 25);
        $f2g8_19 = self::mul($g8_19, $f2, 26);
        $f2g9_19 = self::mul($g9_19, $f2, 26);
        $f3g0    = self::mul($f3,    $g0, 26);
        $f3g1_2  = self::mul($f3_2,  $g1, 25);
        $f3g2    = self::mul($f3,    $g2, 26);
        $f3g3_2  = self::mul($f3_2,  $g3, 25);
        $f3g4    = self::mul($f3,    $g4, 26);
        $f3g5_2  = self::mul($f3_2,  $g5, 25);
        $f3g6    = self::mul($f3,    $g6, 26);
        $f3g7_38 = self::mul($g7_19, $f3_2, 26);
        $f3g8_19 = self::mul($g8_19, $f3, 25);
        $f3g9_38 = self::mul($g9_19, $f3_2, 26);
        $f4g0    = self::mul($f4,    $g0, 26);
        $f4g1    = self::mul($f4,    $g1, 25);
        $f4g2    = self::mul($f4,    $g2, 26);
        $f4g3    = self::mul($f4,    $g3, 25);
        $f4g4    = self::mul($f4,    $g4, 26);
        $f4g5    = self::mul($f4,    $g5, 25);
        $f4g6_19 = self::mul($g6_19, $f4, 26);
        $f4g7_19 = self::mul($g7_19, $f4, 26);
        $f4g8_19 = self::mul($g8_19, $f4, 26);
        $f4g9_19 = self::mul($g9_19, $f4, 26);
        $f5g0    = self::mul($f5,    $g0, 26);
        $f5g1_2  = self::mul($f5_2,  $g1, 25);
        $f5g2    = self::mul($f5,    $g2, 26);
        $f5g3_2  = self::mul($f5_2,  $g3, 25);
        $f5g4    = self::mul($f5,    $g4, 26);
        $f5g5_38 = self::mul($g5_19, $f5_2, 26);
        $f5g6_19 = self::mul($g6_19, $f5, 25);
        $f5g7_38 = self::mul($g7_19, $f5_2, 26);
        $f5g8_19 = self::mul($g8_19, $f5, 25);
        $f5g9_38 = self::mul($g9_19, $f5_2, 26);
        $f6g0    = self::mul($f6,    $g0, 26);
        $f6g1    = self::mul($f6,    $g1, 25);
        $f6g2    = self::mul($f6,    $g2, 26);
        $f6g3    = self::mul($f6,    $g3, 25);
        $f6g4_19 = self::mul($g4_19, $f6, 26);
        $f6g5_19 = self::mul($g5_19, $f6, 26);
        $f6g6_19 = self::mul($g6_19, $f6, 26);
        $f6g7_19 = self::mul($g7_19, $f6, 26);
        $f6g8_19 = self::mul($g8_19, $f6, 26);
        $f6g9_19 = self::mul($g9_19, $f6, 26);
        $f7g0    = self::mul($f7,    $g0, 26);
        $f7g1_2  = self::mul($f7_2,  $g1, 25);
        $f7g2    = self::mul($f7,    $g2, 26);
        $f7g3_38 = self::mul($g3_19, $f7_2, 26);
        $f7g4_19 = self::mul($g4_19, $f7, 26);
        $f7g5_38 = self::mul($g5_19, $f7_2, 26);
        $f7g6_19 = self::mul($g6_19, $f7, 25);
        $f7g7_38 = self::mul($g7_19, $f7_2, 26);
        $f7g8_19 = self::mul($g8_19, $f7, 25);
        $f7g9_38 = self::mul($g9_19,$f7_2, 26);
        $f8g0    = self::mul($f8,    $g0, 26);
        $f8g1    = self::mul($f8,    $g1, 25);
        $f8g2_19 = self::mul($g2_19, $f8, 26);
        $f8g3_19 = self::mul($g3_19, $f8, 26);
        $f8g4_19 = self::mul($g4_19, $f8, 26);
        $f8g5_19 = self::mul($g5_19, $f8, 26);
        $f8g6_19 = self::mul($g6_19, $f8, 26);
        $f8g7_19 = self::mul($g7_19, $f8, 26);
        $f8g8_19 = self::mul($g8_19, $f8, 26);
        $f8g9_19 = self::mul($g9_19, $f8, 26);
        $f9g0    = self::mul($f9,    $g0, 26);
        $f9g1_38 = self::mul($g1_19, $f9_2, 26);
        $f9g2_19 = self::mul($g2_19, $f9, 25);
        $f9g3_38 = self::mul($g3_19, $f9_2, 26);
        $f9g4_19 = self::mul($g4_19, $f9, 25);
        $f9g5_38 = self::mul($g5_19, $f9_2, 26);
        $f9g6_19 = self::mul($g6_19, $f9, 25);
        $f9g7_38 = self::mul($g7_19, $f9_2, 26);
        $f9g8_19 = self::mul($g8_19, $f9, 25);
        $f9g9_38 = self::mul($g9_19, $f9_2, 26);

        $h0 = $f0g0 + $f1g9_38 + $f2g8_19 + $f3g7_38 + $f4g6_19 + $f5g5_38 + $f6g4_19 + $f7g3_38 + $f8g2_19 + $f9g1_38;
        $h1 = $f0g1 + $f1g0    + $f2g9_19 + $f3g8_19 + $f4g7_19 + $f5g6_19 + $f6g5_19 + $f7g4_19 + $f8g3_19 + $f9g2_19;
        $h2 = $f0g2 + $f1g1_2  + $f2g0    + $f3g9_38 + $f4g8_19 + $f5g7_38 + $f6g6_19 + $f7g5_38 + $f8g4_19 + $f9g3_38;
        $h3 = $f0g3 + $f1g2    + $f2g1    + $f3g0    + $f4g9_19 + $f5g8_19 + $f6g7_19 + $f7g6_19 + $f8g5_19 + $f9g4_19;
        $h4 = $f0g4 + $f1g3_2  + $f2g2    + $f3g1_2  + $f4g0    + $f5g9_38 + $f6g8_19 + $f7g7_38 + $f8g6_19 + $f9g5_38;
        $h5 = $f0g5 + $f1g4    + $f2g3    + $f3g2    + $f4g1    + $f5g0    + $f6g9_19 + $f7g8_19 + $f8g7_19 + $f9g6_19;
        $h6 = $f0g6 + $f1g5_2  + $f2g4    + $f3g3_2  + $f4g2    + $f5g1_2  + $f6g0    + $f7g9_38 + $f8g8_19 + $f9g7_38;
        $h7 = $f0g7 + $f1g6    + $f2g5    + $f3g4    + $f4g3    + $f5g2    + $f6g1    + $f7g0    + $f8g9_19 + $f9g8_19;
        $h8 = $f0g8 + $f1g7_2  + $f2g6    + $f3g5_2  + $f4g4    + $f5g3_2  + $f6g2    + $f7g1_2  + $f8g0    + $f9g9_38;
        $h9 = $f0g9 + $f1g8    + $f2g7    + $f3g6    + $f4g5    + $f5g4    + $f6g3    + $f7g2    + $f8g1    + $f9g0   ;

        $carry0 = ($h0 + (1 << 25)) >> 26;
        $h1 += $carry0;
        $h0 -= $carry0 << 26;
        $carry4 = ($h4 + (1 << 25)) >> 26;
        $h5 += $carry4;
        $h4 -= $carry4 << 26;

        $carry1 = ($h1 + (1 << 24)) >> 25;
        $h2 += $carry1;
        $h1 -= $carry1 << 25;
        $carry5 = ($h5 + (1 << 24)) >> 25;
        $h6 += $carry5;
        $h5 -= $carry5 << 25;

        $carry2 = ($h2 + (1 << 25)) >> 26;
        $h3 += $carry2;
        $h2 -= $carry2 << 26;
        $carry6 = ($h6 + (1 << 25)) >> 26;
        $h7 += $carry6;
        $h6 -= $carry6 << 26;

        $carry3 = ($h3 + (1 << 24)) >> 25;
        $h4 += $carry3;
        $h3 -= $carry3 << 25;
        $carry7 = ($h7 + (1 << 24)) >> 25;
        $h8 += $carry7;
        $h7 -= $carry7 << 25;

        $carry4 = ($h4 + (1 << 25)) >> 26;
        $h5 += $carry4;
        $h4 -= $carry4 << 26;
        $carry8 = ($h8 + (1 << 25)) >> 26;
        $h9 += $carry8;
        $h8 -= $carry8 << 26;

        $carry9 = ($h9 + (1 << 24)) >> 25;
        $h0 += self::mul($carry9, 19, 5);
        $h9 -= $carry9 << 25;

        $carry0 = ($h0 + (1 << 25)) >> 26;
        $h1 += $carry0;
        $h0 -= $carry0 << 26;

        return self::fe_normalize(
            ParagonIE_Sodium_Core_Curve25519_Fe::fromArray(
                array(
                    (int) $h0,
                    (int) $h1,
                    (int) $h2,
                    (int) $h3,
                    (int) $h4,
                    (int) $h5,
                    (int) $h6,
                    (int) $h7,
                    (int) $h8,
                    (int) $h9
                )
            )
        );
    }

    /**
     * Get the negative values for each piece of the field element.
     *
     * h = -f
     *
     * @internal You should not use this directly from another application
     *
     * @param ParagonIE_Sodium_Core_Curve25519_Fe $f
     * @return ParagonIE_Sodium_Core_Curve25519_Fe
     * @psalm-suppress MixedAssignment
     */
    public static function fe_neg(ParagonIE_Sodium_Core_Curve25519_Fe $f)
    {
        $h = new ParagonIE_Sodium_Core_Curve25519_Fe();
        for ($i = 0; $i < 10; ++$i) {
            $h[$i] = -$f[$i];
        }
        return self::fe_normalize($h);
    }

    /**
     * Square a field element
     *
     * h = f * f
     *
     * @internal You should not use this directly from another application
     *
     * @param ParagonIE_Sodium_Core_Curve25519_Fe $f
     * @return ParagonIE_Sodium_Core_Curve25519_Fe
     */
    public static function fe_sq(ParagonIE_Sodium_Core_Curve25519_Fe $f)
    {
        $f = self::fe_normalize($f);
        $f0 = (int) $f[0];
        $f1 = (int) $f[1];
        $f2 = (int) $f[2];
        $f3 = (int) $f[3];
        $f4 = (int) $f[4];
        $f5 = (int) $f[5];
        $f6 = (int) $f[6];
        $f7 = (int) $f[7];
        $f8 = (int) $f[8];
        $f9 = (int) $f[9];

        $f0_2 = $f0 << 1;
        $f1_2 = $f1 << 1;
        $f2_2 = $f2 << 1;
        $f3_2 = $f3 << 1;
        $f4_2 = $f4 << 1;
        $f5_2 = $f5 << 1;
        $f6_2 = $f6 << 1;
        $f7_2 = $f7 << 1;
        $f5_38 = self::mul($f5, 38, 6);
        $f6_19 = self::mul($f6, 19, 5);
        $f7_38 = self::mul($f7, 38, 6);
        $f8_19 = self::mul($f8, 19, 5);
        $f9_38 = self::mul($f9, 38, 6);
        $f0f0    = self::mul($f0,    $f0,    26);
        $f0f1_2  = self::mul($f0_2,  $f1,    26);
        $f0f2_2  = self::mul($f0_2,  $f2,    26);
        $f0f3_2  = self::mul($f0_2,  $f3,    26);
        $f0f4_2  = self::mul($f0_2,  $f4,    26);
        $f0f5_2  = self::mul($f0_2,  $f5,    26);
        $f0f6_2  = self::mul($f0_2,  $f6,    26);
        $f0f7_2  = self::mul($f0_2,  $f7,    26);
        $f0f8_2  = self::mul($f0_2,  $f8,    26);
        $f0f9_2  = self::mul($f0_2,  $f9,    26);
        $f1f1_2  = self::mul($f1_2,  $f1,    26);
        $f1f2_2  = self::mul($f1_2,  $f2,    26);
        $f1f3_4  = self::mul($f1_2,  $f3_2,  26);
        $f1f4_2  = self::mul($f1_2,  $f4,    26);
        $f1f5_4  = self::mul($f1_2,  $f5_2,  26);
        $f1f6_2  = self::mul($f1_2,  $f6,    26);
        $f1f7_4  = self::mul($f1_2,  $f7_2,  26);
        $f1f8_2  = self::mul($f1_2,  $f8,    26);
        $f1f9_76 = self::mul($f9_38, $f1_2,  27);
        $f2f2    = self::mul($f2,    $f2,    27);
        $f2f3_2  = self::mul($f2_2,  $f3,    27);
        $f2f4_2  = self::mul($f2_2,  $f4,    27);
        $f2f5_2  = self::mul($f2_2,  $f5,    27);
        $f2f6_2  = self::mul($f2_2,  $f6,    27);
        $f2f7_2  = self::mul($f2_2,  $f7,    27);
        $f2f8_38 = self::mul($f8_19, $f2_2,  27);
        $f2f9_38 = self::mul($f9_38, $f2,    26);
        $f3f3_2  = self::mul($f3_2,  $f3,    26);
        $f3f4_2  = self::mul($f3_2,  $f4,    26);
        $f3f5_4  = self::mul($f3_2,  $f5_2,  26);
        $f3f6_2  = self::mul($f3_2,  $f6,    26);
        $f3f7_76 = self::mul($f7_38, $f3_2,  26);
        $f3f8_38 = self::mul($f8_19, $f3_2,  26);
        $f3f9_76 = self::mul($f9_38, $f3_2,  26);
        $f4f4    = self::mul($f4,    $f4,    26);
        $f4f5_2  = self::mul($f4_2,  $f5,    26);
        $f4f6_38 = self::mul($f6_19, $f4_2,  27);
        $f4f7_38 = self::mul($f7_38, $f4,    26);
        $f4f8_38 = self::mul($f8_19, $f4_2,  27);
        $f4f9_38 = self::mul($f9_38, $f4,    26);
        $f5f5_38 = self::mul($f5_38, $f5,    26);
        $f5f6_38 = self::mul($f6_19, $f5_2,  26);
        $f5f7_76 = self::mul($f7_38, $f5_2,  26);
        $f5f8_38 = self::mul($f8_19, $f5_2,  26);
        $f5f9_76 = self::mul($f9_38, $f5_2,  26);
        $f6f6_19 = self::mul($f6_19, $f6,    26);
        $f6f7_38 = self::mul($f7_38, $f6,    26);
        $f6f8_38 = self::mul($f8_19, $f6_2,  27);
        $f6f9_38 = self::mul($f9_38, $f6,    26);
        $f7f7_38 = self::mul($f7_38, $f7,    26);
        $f7f8_38 = self::mul($f8_19, $f7_2,  26);
        $f7f9_76 = self::mul($f9_38, $f7_2,  26);
        $f8f8_19 = self::mul($f8_19, $f8,    26);
        $f8f9_38 = self::mul($f9_38, $f8,    26);
        $f9f9_38 = self::mul($f9_38, $f9,    26);
        $h0 = $f0f0   + $f1f9_76 + $f2f8_38 + $f3f7_76 + $f4f6_38 + $f5f5_38;
        $h1 = $f0f1_2 + $f2f9_38 + $f3f8_38 + $f4f7_38 + $f5f6_38;
        $h2 = $f0f2_2 + $f1f1_2  + $f3f9_76 + $f4f8_38 + $f5f7_76 + $f6f6_19;
        $h3 = $f0f3_2 + $f1f2_2  + $f4f9_38 + $f5f8_38 + $f6f7_38;
        $h4 = $f0f4_2 + $f1f3_4  + $f2f2    + $f5f9_76 + $f6f8_38 + $f7f7_38;
        $h5 = $f0f5_2 + $f1f4_2  + $f2f3_2  + $f6f9_38 + $f7f8_38;
        $h6 = $f0f6_2 + $f1f5_4  + $f2f4_2  + $f3f3_2  + $f7f9_76 + $f8f8_19;
        $h7 = $f0f7_2 + $f1f6_2  + $f2f5_2  + $f3f4_2  + $f8f9_38;
        $h8 = $f0f8_2 + $f1f7_4  + $f2f6_2  + $f3f5_4  + $f4f4    + $f9f9_38;
        $h9 = $f0f9_2 + $f1f8_2  + $f2f7_2  + $f3f6_2  + $f4f5_2;

        $carry0 = ($h0 + (1 << 25)) >> 26;
        $h1 += $carry0;
        $h0 -= $carry0 << 26;
        $carry4 = ($h4 + (1 << 25)) >> 26;
        $h5 += $carry4;
        $h4 -= $carry4 << 26;

        $carry1 = ($h1 + (1 << 24)) >> 25;
        $h2 += $carry1;
        $h1 -= $carry1 << 25;
        $carry5 = ($h5 + (1 << 24)) >> 25;
        $h6 += $carry5;
        $h5 -= $carry5 << 25;

        $carry2 = ($h2 + (1 << 25)) >> 26;
        $h3 += $carry2;
        $h2 -= $carry2 << 26;
        $carry6 = ($h6 + (1 << 25)) >> 26;
        $h7 += $carry6;
        $h6 -= $carry6 << 26;

        $carry3 = ($h3 + (1 << 24)) >> 25;
        $h4 += $carry3;
        $h3 -= $carry3 << 25;
        $carry7 = ($h7 + (1 << 24)) >> 25;
        $h8 += $carry7;
        $h7 -= $carry7 << 25;

        $carry4 = ($h4 + (1 << 25)) >> 26;
        $h5 += $carry4;
        $h4 -= $carry4 << 26;
        $carry8 = ($h8 + (1 << 25)) >> 26;
        $h9 += $carry8;
        $h8 -= $carry8 << 26;

        $carry9 = ($h9 + (1 << 24)) >> 25;
        $h0 += self::mul($carry9, 19, 5);
        $h9 -= $carry9 << 25;

        $carry0 = ($h0 + (1 << 25)) >> 26;
        $h1 += $carry0;
        $h0 -= $carry0 << 26;

        return self::fe_normalize(
            ParagonIE_Sodium_Core_Curve25519_Fe::fromArray(
                array(
                    (int) $h0,
                    (int) $h1,
                    (int) $h2,
                    (int) $h3,
                    (int) $h4,
                    (int) $h5,
                    (int) $h6,
                    (int) $h7,
                    (int) $h8,
                    (int) $h9
                )
            )
        );
    }


    /**
     * Square and double a field element
     *
     * h = 2 * f * f
     *
     * @internal You should not use this directly from another application
     *
     * @param ParagonIE_Sodium_Core_Curve25519_Fe $f
     * @return ParagonIE_Sodium_Core_Curve25519_Fe
     */
    public static function fe_sq2(ParagonIE_Sodium_Core_Curve25519_Fe $f)
    {
        $f = self::fe_normalize($f);
        $f0 = (int) $f[0];
        $f1 = (int) $f[1];
        $f2 = (int) $f[2];
        $f3 = (int) $f[3];
        $f4 = (int) $f[4];
        $f5 = (int) $f[5];
        $f6 = (int) $f[6];
        $f7 = (int) $f[7];
        $f8 = (int) $f[8];
        $f9 = (int) $f[9];

        $f0_2 = $f0 << 1;
        $f1_2 = $f1 << 1;
        $f2_2 = $f2 << 1;
        $f3_2 = $f3 << 1;
        $f4_2 = $f4 << 1;
        $f5_2 = $f5 << 1;
        $f6_2 = $f6 << 1;
        $f7_2 = $f7 << 1;
        $f5_38 = self::mul($f5, 38, 6); /* 1.959375*2^30 */
        $f6_19 = self::mul($f6, 19, 5); /* 1.959375*2^30 */
        $f7_38 = self::mul($f7, 38, 6); /* 1.959375*2^30 */
        $f8_19 = self::mul($f8, 19, 5); /* 1.959375*2^30 */
        $f9_38 = self::mul($f9, 38, 6); /* 1.959375*2^30 */
        $f0f0 = self::mul($f0, $f0, 24);
        $f0f1_2 = self::mul($f0_2, $f1, 24);
        $f0f2_2 = self::mul($f0_2, $f2, 24);
        $f0f3_2 = self::mul($f0_2, $f3, 24);
        $f0f4_2 = self::mul($f0_2, $f4, 24);
        $f0f5_2 = self::mul($f0_2, $f5, 24);
        $f0f6_2 = self::mul($f0_2, $f6, 24);
        $f0f7_2 = self::mul($f0_2, $f7, 24);
        $f0f8_2 = self::mul($f0_2, $f8, 24);
        $f0f9_2 = self::mul($f0_2, $f9, 24);
        $f1f1_2 = self::mul($f1_2,  $f1, 24);
        $f1f2_2 = self::mul($f1_2,  $f2, 24);
        $f1f3_4 = self::mul($f1_2,  $f3_2, 24);
        $f1f4_2 = self::mul($f1_2,  $f4, 24);
        $f1f5_4 = self::mul($f1_2,  $f5_2, 24);
        $f1f6_2 = self::mul($f1_2,  $f6, 24);
        $f1f7_4 = self::mul($f1_2,  $f7_2, 24);
        $f1f8_2 = self::mul($f1_2,  $f8, 24);
        $f1f9_76 = self::mul($f9_38, $f1_2, 24);
        $f2f2 = self::mul($f2,  $f2, 24);
        $f2f3_2 = self::mul($f2_2,  $f3, 24);
        $f2f4_2 = self::mul($f2_2,  $f4, 24);
        $f2f5_2 = self::mul($f2_2,  $f5, 24);
        $f2f6_2 = self::mul($f2_2,  $f6, 24);
        $f2f7_2 = self::mul($f2_2,  $f7, 24);
        $f2f8_38 = self::mul($f8_19, $f2_2, 25);
        $f2f9_38 = self::mul($f9_38, $f2, 24);
        $f3f3_2 = self::mul($f3_2,  $f3, 24);
        $f3f4_2 = self::mul($f3_2,  $f4, 24);
        $f3f5_4 = self::mul($f3_2,  $f5_2, 24);
        $f3f6_2 = self::mul($f3_2,  $f6, 24);
        $f3f7_76 = self::mul($f7_38, $f3_2, 24);
        $f3f8_38 = self::mul($f8_19, $f3_2, 24);
        $f3f9_76 = self::mul($f9_38, $f3_2, 24);
        $f4f4 = self::mul($f4,  $f4, 24);
        $f4f5_2 = self::mul($f4_2,  $f5, 24);
        $f4f6_38 = self::mul($f6_19, $f4_2, 25);
        $f4f7_38 = self::mul($f7_38, $f4, 24);
        $f4f8_38 = self::mul($f8_19, $f4_2, 25);
        $f4f9_38 = self::mul($f9_38, $f4, 24);
        $f5f5_38 = self::mul($f5_38, $f5, 24);
        $f5f6_38 = self::mul($f6_19, $f5_2, 24);
        $f5f7_76 = self::mul($f7_38, $f5_2, 24);
        $f5f8_38 = self::mul($f8_19, $f5_2, 24);
        $f5f9_76 = self::mul($f9_38, $f5_2, 24);
        $f6f6_19 = self::mul($f6_19, $f6, 24);
        $f6f7_38 = self::mul($f7_38, $f6, 24);
        $f6f8_38 = self::mul($f8_19, $f6_2, 25);
        $f6f9_38 = self::mul($f9_38, $f6, 24);
        $f7f7_38 = self::mul($f7_38, $f7, 24);
        $f7f8_38 = self::mul($f8_19, $f7_2, 24);
        $f7f9_76 = self::mul($f9_38, $f7_2, 24);
        $f8f8_19 = self::mul($f8_19, $f8, 24);
        $f8f9_38 = self::mul($f9_38, $f8, 24);
        $f9f9_38 = self::mul($f9_38, $f9, 24);

        $h0 = (int) ($f0f0 + $f1f9_76 + $f2f8_38 + $f3f7_76 + $f4f6_38 + $f5f5_38) << 1;
        $h1 = (int) ($f0f1_2 + $f2f9_38 + $f3f8_38 + $f4f7_38 + $f5f6_38) << 1;
        $h2 = (int) ($f0f2_2 + $f1f1_2  + $f3f9_76 + $f4f8_38 + $f5f7_76 + $f6f6_19) << 1;
        $h3 = (int) ($f0f3_2 + $f1f2_2  + $f4f9_38 + $f5f8_38 + $f6f7_38) << 1;
        $h4 = (int) ($f0f4_2 + $f1f3_4  + $f2f2    + $f5f9_76 + $f6f8_38 + $f7f7_38) << 1;
        $h5 = (int) ($f0f5_2 + $f1f4_2  + $f2f3_2  + $f6f9_38 + $f7f8_38) << 1;
        $h6 = (int) ($f0f6_2 + $f1f5_4  + $f2f4_2  + $f3f3_2  + $f7f9_76 + $f8f8_19) << 1;
        $h7 = (int) ($f0f7_2 + $f1f6_2  + $f2f5_2  + $f3f4_2  + $f8f9_38) << 1;
        $h8 = (int) ($f0f8_2 + $f1f7_4  + $f2f6_2  + $f3f5_4  + $f4f4    + $f9f9_38) << 1;
        $h9 = (int) ($f0f9_2 + $f1f8_2  + $f2f7_2  + $f3f6_2  + $f4f5_2) << 1;

        $carry0 = ($h0 + (1 << 25)) >> 26;
        $h1 += $carry0;
        $h0 -= $carry0 << 26;
        $carry4 = ($h4 + (1 << 25)) >> 26;
        $h5 += $carry4;
        $h4 -= $carry4 << 26;

        $carry1 = ($h1 + (1 << 24)) >> 25;
        $h2 += $carry1;
        $h1 -= $carry1 << 25;
        $carry5 = ($h5 + (1 << 24)) >> 25;
        $h6 += $carry5;
        $h5 -= $carry5 << 25;

        $carry2 = ($h2 + (1 << 25)) >> 26;
        $h3 += $carry2;
        $h2 -= $carry2 << 26;
        $carry6 = ($h6 + (1 << 25)) >> 26;
        $h7 += $carry6;
        $h6 -= $carry6 << 26;

        $carry3 = ($h3 + (1 << 24)) >> 25;
        $h4 += $carry3;
        $h3 -= $carry3 << 25;
        $carry7 = ($h7 + (1 << 24)) >> 25;
        $h8 += $carry7;
        $h7 -= $carry7 << 25;

        $carry4 = ($h4 + (1 << 25)) >> 26;
        $h5 += $carry4;
        $h4 -= $carry4 << 26;
        $carry8 = ($h8 + (1 << 25)) >> 26;
        $h9 += $carry8;
        $h8 -= $carry8 << 26;

        $carry9 = ($h9 + (1 << 24)) >> 25;
        $h0 += self::mul($carry9, 19, 5);
        $h9 -= $carry9 << 25;

        $carry0 = ($h0 + (1 << 25)) >> 26;
        $h1 += $carry0;
        $h0 -= $carry0 << 26;

        return self::fe_normalize(
            ParagonIE_Sodium_Core_Curve25519_Fe::fromArray(
                array(
                    (int) $h0,
                    (int) $h1,
                    (int) $h2,
                    (int) $h3,
                    (int) $h4,
                    (int) $h5,
                    (int) $h6,
                    (int) $h7,
                    (int) $h8,
                    (int) $h9
                )
            )
        );
    }

    /**
     * @internal You should not use this directly from another application
     *
     * @param ParagonIE_Sodium_Core_Curve25519_Fe $Z
     * @return ParagonIE_Sodium_Core_Curve25519_Fe
     */
    public static function fe_invert(ParagonIE_Sodium_Core_Curve25519_Fe $Z)
    {
        $z = clone $Z;
        $t0 = self::fe_sq($z);
        $t1 = self::fe_sq($t0);
        $t1 = self::fe_sq($t1);
        $t1 = self::fe_mul($z, $t1);
        $t0 = self::fe_mul($t0, $t1);
        $t2 = self::fe_sq($t0);
        $t1 = self::fe_mul($t1, $t2);
        $t2 = self::fe_sq($t1);
        for ($i = 1; $i < 5; ++$i) {
            $t2 = self::fe_sq($t2);
        }
        $t1 = self::fe_mul($t2, $t1);
        $t2 = self::fe_sq($t1);
        for ($i = 1; $i < 10; ++$i) {
            $t2 = self::fe_sq($t2);
        }
        $t2 = self::fe_mul($t2, $t1);
        $t3 = self::fe_sq($t2);
        for ($i = 1; $i < 20; ++$i) {
            $t3 = self::fe_sq($t3);
        }
        $t2 = self::fe_mul($t3, $t2);
        $t2 = self::fe_sq($t2);
        for ($i = 1; $i < 10; ++$i) {
            $t2 = self::fe_sq($t2);
        }
        $t1 = self::fe_mul($t2, $t1);
        $t2 = self::fe_sq($t1);
        for ($i = 1; $i < 50; ++$i) {
            $t2 = self::fe_sq($t2);
        }
        $t2 = self::fe_mul($t2, $t1);
        $t3 = self::fe_sq($t2);
        for ($i = 1; $i < 100; ++$i) {
            $t3 = self::fe_sq($t3);
        }
        $t2 = self::fe_mul($t3, $t2);
        $t2 = self::fe_sq($t2);
        for ($i = 1; $i < 50; ++$i) {
            $t2 = self::fe_sq($t2);
        }
        $t1 = self::fe_mul($t2, $t1);
        $t1 = self::fe_sq($t1);
        for ($i = 1; $i < 5; ++$i) {
            $t1 = self::fe_sq($t1);
        }
        return self::fe_mul($t1, $t0);
    }

    /**
     * @internal You should not use this directly from another application
     *
     * @ref https://github.com/jedisct1/libsodium/blob/68564326e1e9dc57ef03746f85734232d20ca6fb/src/libsodium/crypto_core/curve25519/ref10/curve25519_ref10.c#L1054-L1106
     *
     * @param ParagonIE_Sodium_Core_Curve25519_Fe $z
     * @return ParagonIE_Sodium_Core_Curve25519_Fe
     */
    public static function fe_pow22523(ParagonIE_Sodium_Core_Curve25519_Fe $z)
    {
        $z = self::fe_normalize($z);
        # fe_sq(t0, z);
        # fe_sq(t1, t0);
        # fe_sq(t1, t1);
        # fe_mul(t1, z, t1);
        # fe_mul(t0, t0, t1);
        # fe_sq(t0, t0);
        # fe_mul(t0, t1, t0);
        # fe_sq(t1, t0);
        $t0 = self::fe_sq($z);
        $t1 = self::fe_sq($t0);
        $t1 = self::fe_sq($t1);
        $t1 = self::fe_mul($z, $t1);
        $t0 = self::fe_mul($t0, $t1);
        $t0 = self::fe_sq($t0);
        $t0 = self::fe_mul($t1, $t0);
        $t1 = self::fe_sq($t0);

        # for (i = 1; i < 5; ++i) {
        #     fe_sq(t1, t1);
        # }
        for ($i = 1; $i < 5; ++$i) {
            $t1 = self::fe_sq($t1);
        }

        # fe_mul(t0, t1, t0);
        # fe_sq(t1, t0);
        $t0 = self::fe_mul($t1, $t0);
        $t1 = self::fe_sq($t0);

        # for (i = 1; i < 10; ++i) {
        #     fe_sq(t1, t1);
        # }
        for ($i = 1; $i < 10; ++$i) {
            $t1 = self::fe_sq($t1);
        }

        # fe_mul(t1, t1, t0);
        # fe_sq(t2, t1);
        $t1 = self::fe_mul($t1, $t0);
        $t2 = self::fe_sq($t1);

        # for (i = 1; i < 20; ++i) {
        #     fe_sq(t2, t2);
        # }
        for ($i = 1; $i < 20; ++$i) {
            $t2 = self::fe_sq($t2);
        }

        # fe_mul(t1, t2, t1);
        # fe_sq(t1, t1);
        $t1 = self::fe_mul($t2, $t1);
        $t1 = self::fe_sq($t1);

        # for (i = 1; i < 10; ++i) {
        #     fe_sq(t1, t1);
        # }
        for ($i = 1; $i < 10; ++$i) {
            $t1 = self::fe_sq($t1);
        }

        # fe_mul(t0, t1, t0);
        # fe_sq(t1, t0);
        $t0 = self::fe_mul($t1, $t0);
        $t1 = self::fe_sq($t0);

        # for (i = 1; i < 50; ++i) {
        #     fe_sq(t1, t1);
        # }
        for ($i = 1; $i < 50; ++$i) {
            $t1 = self::fe_sq($t1);
        }

        # fe_mul(t1, t1, t0);
        # fe_sq(t2, t1);
        $t1 = self::fe_mul($t1, $t0);
        $t2 = self::fe_sq($t1);

        # for (i = 1; i < 100; ++i) {
        #     fe_sq(t2, t2);
        # }
        for ($i = 1; $i < 100; ++$i) {
            $t2 = self::fe_sq($t2);
        }

        # fe_mul(t1, t2, t1);
        # fe_sq(t1, t1);
        $t1 = self::fe_mul($t2, $t1);
        $t1 = self::fe_sq($t1);

        # for (i = 1; i < 50; ++i) {
        #     fe_sq(t1, t1);
        # }
        for ($i = 1; $i < 50; ++$i) {
            $t1 = self::fe_sq($t1);
        }

        # fe_mul(t0, t1, t0);
        # fe_sq(t0, t0);
        # fe_sq(t0, t0);
        # fe_mul(out, t0, z);
        $t0 = self::fe_mul($t1, $t0);
        $t0 = self::fe_sq($t0);
        $t0 = self::fe_sq($t0);
        return self::fe_mul($t0, $z);
    }

    /**
     * Subtract two field elements.
     *
     * h = f - g
     *
     * Preconditions:
     * |f| bounded by 1.1*2^25,1.1*2^24,1.1*2^25,1.1*2^24,etc.
     * |g| bounded by 1.1*2^25,1.1*2^24,1.1*2^25,1.1*2^24,etc.
     *
     * Postconditions:
     * |h| bounded by 1.1*2^26,1.1*2^25,1.1*2^26,1.1*2^25,etc.
     *
     * @internal You should not use this directly from another application
     *
     * @param ParagonIE_Sodium_Core_Curve25519_Fe $f
     * @param ParagonIE_Sodium_Core_Curve25519_Fe $g
     * @return ParagonIE_Sodium_Core_Curve25519_Fe
     * @psalm-suppress MixedOperand
     */
    public static function fe_sub(ParagonIE_Sodium_Core_Curve25519_Fe $f, ParagonIE_Sodium_Core_Curve25519_Fe $g)
    {
        return self::fe_normalize(
            ParagonIE_Sodium_Core_Curve25519_Fe::fromArray(
                array(
                    (int) ($f[0] - $g[0]),
                    (int) ($f[1] - $g[1]),
                    (int) ($f[2] - $g[2]),
                    (int) ($f[3] - $g[3]),
                    (int) ($f[4] - $g[4]),
                    (int) ($f[5] - $g[5]),
                    (int) ($f[6] - $g[6]),
                    (int) ($f[7] - $g[7]),
                    (int) ($f[8] - $g[8]),
                    (int) ($f[9] - $g[9])
                )
            )
        );
    }

    /**
     * Add two group elements.
     *
     * r = p + q
     *
     * @internal You should not use this directly from another application
     *
     * @param ParagonIE_Sodium_Core_Curve25519_Ge_P3 $p
     * @param ParagonIE_Sodium_Core_Curve25519_Ge_Cached $q
     * @return ParagonIE_Sodium_Core_Curve25519_Ge_P1p1
     */
    public static function ge_add(
        ParagonIE_Sodium_Core_Curve25519_Ge_P3 $p,
        ParagonIE_Sodium_Core_Curve25519_Ge_Cached $q
    ) {
        $r = new ParagonIE_Sodium_Core_Curve25519_Ge_P1p1();
        $r->X = self::fe_add($p->Y, $p->X);
        $r->Y = self::fe_sub($p->Y, $p->X);
        $r->Z = self::fe_mul($r->X, $q->YplusX);
        $r->Y = self::fe_mul($r->Y, $q->YminusX);
        $r->T = self::fe_mul($q->T2d, $p->T);
        $r->X = self::fe_mul($p->Z, $q->Z);
        $t0   = self::fe_add($r->X, $r->X);
        $r->X = self::fe_sub($r->Z, $r->Y);
        $r->Y = self::fe_add($r->Z, $r->Y);
        $r->Z = self::fe_add($t0, $r->T);
        $r->T = self::fe_sub($t0, $r->T);
        return $r;
    }

    /**
     * @internal You should not use this directly from another application
     *
     * @ref https://github.com/jedisct1/libsodium/blob/157c4a80c13b117608aeae12178b2d38825f9f8f/src/libsodium/crypto_core/curve25519/ref10/curve25519_ref10.c#L1185-L1215
     * @param string $a
     * @return array<int, mixed>
     * @throws SodiumException
     * @throws TypeError
     */
    public static function slide($a)
    {
        if (self::strlen($a) < 256) {
            if (self::strlen($a) < 16) {
                $a = str_pad($a, 256, '0', STR_PAD_RIGHT);
            }
        }
        /** @var array<int, int> $r */
        $r = array();

        /** @var int $i */
        for ($i = 0; $i < 256; ++$i) {
            $r[$i] = (int) (
                1 & (
                    self::chrToInt($a[(int) ($i >> 3)])
                        >>
                    ($i & 7)
                )
            );
        }

        for ($i = 0;$i < 256;++$i) {
            if ($r[$i]) {
                for ($b = 1;$b <= 6 && $i + $b < 256;++$b) {
                    if ($r[$i + $b]) {
                        if ($r[$i] + ($r[$i + $b] << $b) <= 15) {
                            $r[$i] += $r[$i + $b] << $b;
                            $r[$i + $b] = 0;
                        } elseif ($r[$i] - ($r[$i + $b] << $b) >= -15) {
                            $r[$i] -= $r[$i + $b] << $b;
                            for ($k = $i + $b; $k < 256; ++$k) {
                                if (!$r[$k]) {
                                    $r[$k] = 1;
                                    break;
                                }
                                $r[$k] = 0;
                            }
                        } else {
                            break;
                        }
                    }
                }
            }
        }
        return $r;
    }

    /**
     * @internal You should not use this directly from another application
     *
     * @param string $s
     * @return ParagonIE_Sodium_Core_Curve25519_Ge_P3
     * @throws SodiumException
     * @throws TypeError
     */
    public static function ge_frombytes_negate_vartime($s)
    {
        static $d = null;
        if (!$d) {
            $d = ParagonIE_Sodium_Core_Curve25519_Fe::fromArray(self::$d);
        }

        # fe_frombytes(h->Y,s);
        # fe_1(h->Z);
        $h = new ParagonIE_Sodium_Core_Curve25519_Ge_P3(
            self::fe_0(),
            self::fe_frombytes($s),
            self::fe_1()
        );

        # fe_sq(u,h->Y);
        # fe_mul(v,u,d);
        # fe_sub(u,u,h->Z);       /* u = y^2-1 */
        # fe_add(v,v,h->Z);       /* v = dy^2+1 */
        $u = self::fe_sq($h->Y);
        /** @var ParagonIE_Sodium_Core_Curve25519_Fe $d */
        $v = self::fe_mul($u, $d);
        $u = self::fe_sub($u, $h->Z); /* u =  y^2 - 1 */
        $v = self::fe_add($v, $h->Z); /* v = dy^2 + 1 */

        # fe_sq(v3,v);
        # fe_mul(v3,v3,v);        /* v3 = v^3 */
        # fe_sq(h->X,v3);
        # fe_mul(h->X,h->X,v);
        # fe_mul(h->X,h->X,u);    /* x = uv^7 */
        $v3 = self::fe_sq($v);
        $v3 = self::fe_mul($v3, $v); /* v3 = v^3 */
        $h->X = self::fe_sq($v3);
        $h->X = self::fe_mul($h->X, $v);
        $h->X = self::fe_mul($h->X, $u); /* x = uv^7 */

        # fe_pow22523(h->X,h->X); /* x = (uv^7)^((q-5)/8) */
        # fe_mul(h->X,h->X,v3);
        # fe_mul(h->X,h->X,u);    /* x = uv^3(uv^7)^((q-5)/8) */
        $h->X = self::fe_pow22523($h->X); /* x = (uv^7)^((q-5)/8) */
        $h->X = self::fe_mul($h->X, $v3);
        $h->X = self::fe_mul($h->X, $u); /* x = uv^3(uv^7)^((q-5)/8) */

        # fe_sq(vxx,h->X);
        # fe_mul(vxx,vxx,v);
        # fe_sub(check,vxx,u);    /* vx^2-u */
        $vxx = self::fe_sq($h->X);
        $vxx = self::fe_mul($vxx, $v);
        $check = self::fe_sub($vxx, $u); /* vx^2 - u */

        # if (fe_isnonzero(check)) {
        #     fe_add(check,vxx,u);  /* vx^2+u */
        #     if (fe_isnonzero(check)) {
        #         return -1;
        #     }
        #     fe_mul(h->X,h->X,sqrtm1);
        # }
        if (self::fe_isnonzero($check)) {
            $check = self::fe_add($vxx, $u); /* vx^2 + u */
            if (self::fe_isnonzero($check)) {
                throw new RangeException('Internal check failed.');
            }
            $h->X = self::fe_mul(
                $h->X,
                ParagonIE_Sodium_Core_Curve25519_Fe::fromArray(self::$sqrtm1)
            );
        }

        # if (fe_isnegative(h->X) == (s[31] >> 7)) {
        #     fe_neg(h->X,h->X);
        # }
        $i = self::chrToInt($s[31]);
        if (self::fe_isnegative($h->X) === ($i >> 7)) {
            $h->X = self::fe_neg($h->X);
        }

        # fe_mul(h->T,h->X,h->Y);
        $h->T = self::fe_mul($h->X, $h->Y);
        return $h;
    }

    /**
     * @internal You should not use this directly from another application
     *
     * @param ParagonIE_Sodium_Core_Curve25519_Ge_P1p1 $R
     * @param ParagonIE_Sodium_Core_Curve25519_Ge_P3 $p
     * @param ParagonIE_Sodium_Core_Curve25519_Ge_Precomp $q
     * @return ParagonIE_Sodium_Core_Curve25519_Ge_P1p1
     */
    public static function ge_madd(
        ParagonIE_Sodium_Core_Curve25519_Ge_P1p1 $R,
        ParagonIE_Sodium_Core_Curve25519_Ge_P3 $p,
        ParagonIE_Sodium_Core_Curve25519_Ge_Precomp $q
    ) {
        $r = clone $R;
        $r->X = self::fe_add($p->Y, $p->X);
        $r->Y = self::fe_sub($p->Y, $p->X);
        $r->Z = self::fe_mul($r->X, $q->yplusx);
        $r->Y = self::fe_mul($r->Y, $q->yminusx);
        $r->T = self::fe_mul($q->xy2d, $p->T);
        $t0 = self::fe_add(clone $p->Z, clone $p->Z);
        $r->X = self::fe_sub($r->Z, $r->Y);
        $r->Y = self::fe_add($r->Z, $r->Y);
        $r->Z = self::fe_add($t0, $r->T);
        $r->T = self::fe_sub($t0, $r->T);

        return $r;
    }

    /**
     * @internal You should not use this directly from another application
     *
     * @param ParagonIE_Sodium_Core_Curve25519_Ge_P1p1 $R
     * @param ParagonIE_Sodium_Core_Curve25519_Ge_P3 $p
     * @param ParagonIE_Sodium_Core_Curve25519_Ge_Precomp $q
     * @return ParagonIE_Sodium_Core_Curve25519_Ge_P1p1
     */
    public static function ge_msub(
        ParagonIE_Sodium_Core_Curve25519_Ge_P1p1 $R,
        ParagonIE_Sodium_Core_Curve25519_Ge_P3 $p,
        ParagonIE_Sodium_Core_Curve25519_Ge_Precomp $q
    ) {
        $r = clone $R;

        $r->X = self::fe_add($p->Y, $p->X);
        $r->Y = self::fe_sub($p->Y, $p->X);
        $r->Z = self::fe_mul($r->X, $q->yminusx);
        $r->Y = self::fe_mul($r->Y, $q->yplusx);
        $r->T = self::fe_mul($q->xy2d, $p->T);
        $t0 = self::fe_add($p->Z, $p->Z);
        $r->X = self::fe_sub($r->Z, $r->Y);
        $r->Y = self::fe_add($r->Z, $r->Y);
        $r->Z = self::fe_sub($t0, $r->T);
        $r->T = self::fe_add($t0, $r->T);

        return $r;
    }

    /**
     * @internal You should not use this directly from another application
     *
     * @param ParagonIE_Sodium_Core_Curve25519_Ge_P1p1 $p
     * @return ParagonIE_Sodium_Core_Curve25519_Ge_P2
     */
    public static function ge_p1p1_to_p2(ParagonIE_Sodium_Core_Curve25519_Ge_P1p1 $p)
    {
        $r = new ParagonIE_Sodium_Core_Curve25519_Ge_P2();
        $r->X = self::fe_mul($p->X, $p->T);
        $r->Y = self::fe_mul($p->Y, $p->Z);
        $r->Z = self::fe_mul($p->Z, $p->T);
        return $r;
    }

    /**
     * @internal You should not use this directly from another application
     *
     * @param ParagonIE_Sodium_Core_Curve25519_Ge_P1p1 $p
     * @return ParagonIE_Sodium_Core_Curve25519_Ge_P3
     */
    public static function ge_p1p1_to_p3(ParagonIE_Sodium_Core_Curve25519_Ge_P1p1 $p)
    {
        $r = new ParagonIE_Sodium_Core_Curve25519_Ge_P3();
        $r->X = self::fe_mul($p->X, $p->T);
        $r->Y = self::fe_mul($p->Y, $p->Z);
        $r->Z = self::fe_mul($p->Z, $p->T);
        $r->T = self::fe_mul($p->X, $p->Y);
        return $r;
    }

    /**
     * @internal You should not use this directly from another application
     *
     * @return ParagonIE_Sodium_Core_Curve25519_Ge_P2
     */
    public static function ge_p2_0()
    {
        return new ParagonIE_Sodium_Core_Curve25519_Ge_P2(
            self::fe_0(),
            self::fe_1(),
            self::fe_1()
        );
    }

    /**
     * @internal You should not use this directly from another application
     *
     * @param ParagonIE_Sodium_Core_Curve25519_Ge_P2 $p
     * @return ParagonIE_Sodium_Core_Curve25519_Ge_P1p1
     */
    public static function ge_p2_dbl(ParagonIE_Sodium_Core_Curve25519_Ge_P2 $p)
    {
        $r = new ParagonIE_Sodium_Core_Curve25519_Ge_P1p1();

        $r->X = self::fe_sq($p->X);
        $r->Z = self::fe_sq($p->Y);
        $r->T = self::fe_sq2($p->Z);
        $r->Y = self::fe_add($p->X, $p->Y);
        $t0   = self::fe_sq($r->Y);
        $r->Y = self::fe_add($r->Z, $r->X);
        $r->Z = self::fe_sub($r->Z, $r->X);
        $r->X = self::fe_sub($t0, $r->Y);
        $r->T = self::fe_sub($r->T, $r->Z);

        return $r;
    }

    /**
     * @internal You should not use this directly from another application
     *
     * @return ParagonIE_Sodium_Core_Curve25519_Ge_P3
     */
    public static function ge_p3_0()
    {
        return new ParagonIE_Sodium_Core_Curve25519_Ge_P3(
            self::fe_0(),
            self::fe_1(),
            self::fe_1(),
            self::fe_0()
        );
    }

    /**
     * @internal You should not use this directly from another application
     *
     * @param ParagonIE_Sodium_Core_Curve25519_Ge_P3 $p
     * @return ParagonIE_Sodium_Core_Curve25519_Ge_Cached
     */
    public static function ge_p3_to_cached(ParagonIE_Sodium_Core_Curve25519_Ge_P3 $p)
    {
        static $d2 = null;
        if ($d2 === null) {
            $d2 = ParagonIE_Sodium_Core_Curve25519_Fe::fromArray(self::$d2);
        }
        /** @var ParagonIE_Sodium_Core_Curve25519_Fe $d2 */
        $r = new ParagonIE_Sodium_Core_Curve25519_Ge_Cached();
        $r->YplusX = self::fe_add($p->Y, $p->X);
        $r->YminusX = self::fe_sub($p->Y, $p->X);
        $r->Z = self::fe_copy($p->Z);
        $r->T2d = self::fe_mul($p->T, $d2);
        return $r;
    }

    /**
     * @internal You should not use this directly from another application
     *
     * @param ParagonIE_Sodium_Core_Curve25519_Ge_P3 $p
     * @return ParagonIE_Sodium_Core_Curve25519_Ge_P2
     */
    public static function ge_p3_to_p2(ParagonIE_Sodium_Core_Curve25519_Ge_P3 $p)
    {
        return new ParagonIE_Sodium_Core_Curve25519_Ge_P2(
            self::fe_copy($p->X),
            self::fe_copy($p->Y),
            self::fe_copy($p->Z)
        );
    }

    /**
     * @internal You should not use this directly from another application
     *
     * @param ParagonIE_Sodium_Core_Curve25519_Ge_P3 $h
     * @return string
     * @throws SodiumException
     * @throws TypeError
     */
    public static function ge_p3_tobytes(ParagonIE_Sodium_Core_Curve25519_Ge_P3 $h)
    {
        $recip = self::fe_invert($h->Z);
        $x = self::fe_mul($h->X, $recip);
        $y = self::fe_mul($h->Y, $recip);
        $s = self::fe_tobytes($y);
        $s[31] = self::intToChr(
            self::chrToInt($s[31]) ^ (self::fe_isnegative($x) << 7)
        );
        return $s;
    }

    /**
     * @internal You should not use this directly from another application
     *
     * @param ParagonIE_Sodium_Core_Curve25519_Ge_P3 $p
     * @return ParagonIE_Sodium_Core_Curve25519_Ge_P1p1
     */
    public static function ge_p3_dbl(ParagonIE_Sodium_Core_Curve25519_Ge_P3 $p)
    {
        $q = self::ge_p3_to_p2($p);
        return self::ge_p2_dbl($q);
    }

    /**
     * @return ParagonIE_Sodium_Core_Curve25519_Ge_Precomp
     */
    public static function ge_precomp_0()
    {
        return new ParagonIE_Sodium_Core_Curve25519_Ge_Precomp(
            self::fe_1(),
            self::fe_1(),
            self::fe_0()
        );
    }

    /**
     * @internal You should not use this directly from another application
     *
     * @param int $b
     * @param int $c
     * @return int
     */
    public static function equal($b, $c)
    {
        return (int) ((($b ^ $c) - 1) >> 31) & 1;
    }

    /**
     * @internal You should not use this directly from another application
     *
     * @param int|string $char
     * @return int (1 = yes, 0 = no)
     * @throws SodiumException
     * @throws TypeError
     */
    public static function negative($char)
    {
        if (is_int($char)) {
            return ($char >> 63) & 1;
        }
        $x = self::chrToInt(self::substr($char, 0, 1));
        return (int) ($x >> 63);
    }

    /**
     * Conditional move
     *
     * @internal You should not use this directly from another application
     *
     * @param ParagonIE_Sodium_Core_Curve25519_Ge_Precomp $t
     * @param ParagonIE_Sodium_Core_Curve25519_Ge_Precomp $u
     * @param int $b
     * @return ParagonIE_Sodium_Core_Curve25519_Ge_Precomp
     */
    public static function cmov(
        ParagonIE_Sodium_Core_Curve25519_Ge_Precomp $t,
        ParagonIE_Sodium_Core_Curve25519_Ge_Precomp $u,
        $b
    ) {
        if (!is_int($b)) {
            throw new InvalidArgumentException('Expected an integer.');
        }
        return new ParagonIE_Sodium_Core_Curve25519_Ge_Precomp(
            self::fe_cmov($t->yplusx,  $u->yplusx,  $b),
            self::fe_cmov($t->yminusx, $u->yminusx, $b),
            self::fe_cmov($t->xy2d,    $u->xy2d,    $b)
        );
    }

    /**
     * @param ParagonIE_Sodium_Core_Curve25519_Ge_Cached $t
     * @param ParagonIE_Sodium_Core_Curve25519_Ge_Cached $u
     * @param int $b
     * @return ParagonIE_Sodium_Core_Curve25519_Ge_Cached
     */
    public static function ge_cmov_cached(
        ParagonIE_Sodium_Core_Curve25519_Ge_Cached $t,
        ParagonIE_Sodium_Core_Curve25519_Ge_Cached $u,
        $b
    ) {
        $b &= 1;
        $ret = new ParagonIE_Sodium_Core_Curve25519_Ge_Cached();
        $ret->YplusX  = self::fe_cmov($t->YplusX,  $u->YplusX,  $b);
        $ret->YminusX = self::fe_cmov($t->YminusX, $u->YminusX, $b);
        $ret->Z       = self::fe_cmov($t->Z,       $u->Z,       $b);
        $ret->T2d     = self::fe_cmov($t->T2d,     $u->T2d,     $b);
        return $ret;
    }

    /**
     * @param ParagonIE_Sodium_Core_Curve25519_Ge_Cached[] $cached
     * @param int $b
     * @return ParagonIE_Sodium_Core_Curve25519_Ge_Cached
     * @throws SodiumException
     */
    public static function ge_cmov8_cached(array $cached, $b)
    {
        // const unsigned char bnegative = negative(b);
        // const unsigned char babs      = b - (((-bnegative) & b) * ((signed char) 1 << 1));
        $bnegative = self::negative($b);
        $babs = $b - (((-$bnegative) & $b) << 1);

        // ge25519_cached_0(t);
        $t = new ParagonIE_Sodium_Core_Curve25519_Ge_Cached(
            self::fe_1(),
            self::fe_1(),
            self::fe_1(),
            self::fe_0()
        );

        // ge25519_cmov_cached(t, &cached[0], equal(babs, 1));
        // ge25519_cmov_cached(t, &cached[1], equal(babs, 2));
        // ge25519_cmov_cached(t, &cached[2], equal(babs, 3));
        // ge25519_cmov_cached(t, &cached[3], equal(babs, 4));
        // ge25519_cmov_cached(t, &cached[4], equal(babs, 5));
        // ge25519_cmov_cached(t, &cached[5], equal(babs, 6));
        // ge25519_cmov_cached(t, &cached[6], equal(babs, 7));
        // ge25519_cmov_cached(t, &cached[7], equal(babs, 8));
        for ($x = 0; $x < 8; ++$x) {
            $t = self::ge_cmov_cached($t, $cached[$x], self::equal($babs, $x + 1));
        }

        // fe25519_copy(minust.YplusX, t->YminusX);
        // fe25519_copy(minust.YminusX, t->YplusX);
        // fe25519_copy(minust.Z, t->Z);
        // fe25519_neg(minust.T2d, t->T2d);
        $minust = new ParagonIE_Sodium_Core_Curve25519_Ge_Cached(
            self::fe_copy($t->YminusX),
            self::fe_copy($t->YplusX),
            self::fe_copy($t->Z),
            self::fe_neg($t->T2d)
        );
        return self::ge_cmov_cached($t, $minust, $bnegative);
    }

    /**
     * @internal You should not use this directly from another application
     *
     * @param int $pos
     * @param int $b
     * @return ParagonIE_Sodium_Core_Curve25519_Ge_Precomp
     * @throws SodiumException
     * @throws TypeError
     * @psalm-suppress MixedArgument
     * @psalm-suppress MixedArrayAccess
     * @psalm-suppress MixedArrayOffset
     */
    public static function ge_select($pos = 0, $b = 0)
    {
        static $base = null;
        if ($base === null) {
            $base = array();
            /** @var int $i */
            foreach (self::$base as $i => $bas) {
                for ($j = 0; $j < 8; ++$j) {
                    $base[$i][$j] = new ParagonIE_Sodium_Core_Curve25519_Ge_Precomp(
                        ParagonIE_Sodium_Core_Curve25519_Fe::fromArray($bas[$j][0]),
                        ParagonIE_Sodium_Core_Curve25519_Fe::fromArray($bas[$j][1]),
                        ParagonIE_Sodium_Core_Curve25519_Fe::fromArray($bas[$j][2])
                    );
                }
            }
        }
        /** @var array<int, array<int, ParagonIE_Sodium_Core_Curve25519_Ge_Precomp>> $base */
        if (!is_int($pos)) {
            throw new InvalidArgumentException('Position must be an integer');
        }
        if ($pos < 0 || $pos > 31) {
            throw new RangeException('Position is out of range [0, 31]');
        }

        $bnegative = self::negative($b);
        $babs = $b - (((-$bnegative) & $b) << 1);

        $t = self::ge_precomp_0();
        for ($i = 0; $i < 8; ++$i) {
            $t = self::cmov(
                $t,
                $base[$pos][$i],
                self::equal($babs, $i + 1)
            );
        }
        $minusT = new ParagonIE_Sodium_Core_Curve25519_Ge_Precomp(
            self::fe_copy($t->yminusx),
            self::fe_copy($t->yplusx),
            self::fe_neg($t->xy2d)
        );
        return self::cmov($t, $minusT, $bnegative);
    }

    /**
     * Subtract two group elements.
     *
     * r = p - q
     *
     * @internal You should not use this directly from another application
     *
     * @param ParagonIE_Sodium_Core_Curve25519_Ge_P3 $p
     * @param ParagonIE_Sodium_Core_Curve25519_Ge_Cached $q
     * @return ParagonIE_Sodium_Core_Curve25519_Ge_P1p1
     */
    public static function ge_sub(
        ParagonIE_Sodium_Core_Curve25519_Ge_P3 $p,
        ParagonIE_Sodium_Core_Curve25519_Ge_Cached $q
    ) {
        $r = new ParagonIE_Sodium_Core_Curve25519_Ge_P1p1();

        $r->X = self::fe_add($p->Y, $p->X);
        $r->Y = self::fe_sub($p->Y, $p->X);
        $r->Z = self::fe_mul($r->X, $q->YminusX);
        $r->Y = self::fe_mul($r->Y, $q->YplusX);
        $r->T = self::fe_mul($q->T2d, $p->T);
        $r->X = self::fe_mul($p->Z, $q->Z);
        $t0 = self::fe_add($r->X, $r->X);
        $r->X = self::fe_sub($r->Z, $r->Y);
        $r->Y = self::fe_add($r->Z, $r->Y);
        $r->Z = self::fe_sub($t0, $r->T);
        $r->T = self::fe_add($t0, $r->T);

        return $r;
    }

    /**
     * Convert a group element to a byte string.
     *
     * @param ParagonIE_Sodium_Core_Curve25519_Ge_P2 $h
     * @return string
     * @throws SodiumException
     * @throws TypeError
     */
    public static function ge_tobytes(ParagonIE_Sodium_Core_Curve25519_Ge_P2 $h)
    {
        $recip = self::fe_invert($h->Z);
        $x = self::fe_mul($h->X, $recip);
        $y = self::fe_mul($h->Y, $recip);
        $s = self::fe_tobytes($y);
        $s[31] = self::intToChr(
            self::chrToInt($s[31]) ^ (self::fe_isnegative($x) << 7)
        );
        return $s;
    }

    /**
     * @internal You should not use this directly from another application
     *
     * @param string $a
     * @param ParagonIE_Sodium_Core_Curve25519_Ge_P3 $A
     * @param string $b
     * @return ParagonIE_Sodium_Core_Curve25519_Ge_P2
     * @throws SodiumException
     * @throws TypeError
     * @psalm-suppress MixedArgument
     * @psalm-suppress MixedArrayAccess
     */
    public static function ge_double_scalarmult_vartime(
        $a,
        ParagonIE_Sodium_Core_Curve25519_Ge_P3 $A,
        $b
    ) {
        /** @var array<int, ParagonIE_Sodium_Core_Curve25519_Ge_Cached> $Ai */
        $Ai = array();

        /** @var array<int, ParagonIE_Sodium_Core_Curve25519_Ge_Precomp> $Bi */
        static $Bi = array();
        if (!$Bi) {
            for ($i = 0; $i < 8; ++$i) {
                $Bi[$i] = new ParagonIE_Sodium_Core_Curve25519_Ge_Precomp(
                    ParagonIE_Sodium_Core_Curve25519_Fe::fromArray(self::$base2[$i][0]),
                    ParagonIE_Sodium_Core_Curve25519_Fe::fromArray(self::$base2[$i][1]),
                    ParagonIE_Sodium_Core_Curve25519_Fe::fromArray(self::$base2[$i][2])
                );
            }
        }
        for ($i = 0; $i < 8; ++$i) {
            $Ai[$i] = new ParagonIE_Sodium_Core_Curve25519_Ge_Cached(
                self::fe_0(),
                self::fe_0(),
                self::fe_0(),
                self::fe_0()
            );
        }

        # slide(aslide,a);
        # slide(bslide,b);
        /** @var array<int, int> $aslide */
        $aslide = self::slide($a);
        /** @var array<int, int> $bslide */
        $bslide = self::slide($b);

        # ge_p3_to_cached(&Ai[0],A);
        # ge_p3_dbl(&t,A); ge_p1p1_to_p3(&A2,&t);
        $Ai[0] = self::ge_p3_to_cached($A);
        $t = self::ge_p3_dbl($A);
        $A2 = self::ge_p1p1_to_p3($t);

        # ge_add(&t,&A2,&Ai[0]); ge_p1p1_to_p3(&u,&t); ge_p3_to_cached(&Ai[1],&u);
        # ge_add(&t,&A2,&Ai[1]); ge_p1p1_to_p3(&u,&t); ge_p3_to_cached(&Ai[2],&u);
        # ge_add(&t,&A2,&Ai[2]); ge_p1p1_to_p3(&u,&t); ge_p3_to_cached(&Ai[3],&u);
        # ge_add(&t,&A2,&Ai[3]); ge_p1p1_to_p3(&u,&t); ge_p3_to_cached(&Ai[4],&u);
        # ge_add(&t,&A2,&Ai[4]); ge_p1p1_to_p3(&u,&t); ge_p3_to_cached(&Ai[5],&u);
        # ge_add(&t,&A2,&Ai[5]); ge_p1p1_to_p3(&u,&t); ge_p3_to_cached(&Ai[6],&u);
        # ge_add(&t,&A2,&Ai[6]); ge_p1p1_to_p3(&u,&t); ge_p3_to_cached(&Ai[7],&u);
        for ($i = 0; $i < 7; ++$i) {
            $t = self::ge_add($A2, $Ai[$i]);
            $u = self::ge_p1p1_to_p3($t);
            $Ai[$i + 1] = self::ge_p3_to_cached($u);
        }

        # ge_p2_0(r);
        $r = self::ge_p2_0();

        # for (i = 255;i >= 0;--i) {
        #     if (aslide[i] || bslide[i]) break;
        # }
        $i = 255;
        for (; $i >= 0; --$i) {
            if ($aslide[$i] || $bslide[$i]) {
                break;
            }
        }

        # for (;i >= 0;--i) {
        for (; $i >= 0; --$i) {
            # ge_p2_dbl(&t,r);
            $t = self::ge_p2_dbl($r);

            # if (aslide[i] > 0) {
            if ($aslide[$i] > 0) {
                # ge_p1p1_to_p3(&u,&t);
                # ge_add(&t,&u,&Ai[aslide[i]/2]);
                $u = self::ge_p1p1_to_p3($t);
                $t = self::ge_add(
                    $u,
                    $Ai[(int) floor($aslide[$i] / 2)]
                );
            # } else if (aslide[i] < 0) {
            } elseif ($aslide[$i] < 0) {
                # ge_p1p1_to_p3(&u,&t);
                # ge_sub(&t,&u,&Ai[(-aslide[i])/2]);
                $u = self::ge_p1p1_to_p3($t);
                $t = self::ge_sub(
                    $u,
                    $Ai[(int) floor(-$aslide[$i] / 2)]
                );
            }

            # if (bslide[i] > 0) {
            if ($bslide[$i] > 0) {
                /** @var int $index */
                $index = (int) floor($bslide[$i] / 2);
                # ge_p1p1_to_p3(&u,&t);
                # ge_madd(&t,&u,&Bi[bslide[i]/2]);
                $u = self::ge_p1p1_to_p3($t);
                $t = self::ge_madd($t, $u, $Bi[$index]);
            # } else if (bslide[i] < 0) {
            } elseif ($bslide[$i] < 0) {
                /** @var int $index */
                $index = (int) floor(-$bslide[$i] / 2);
                # ge_p1p1_to_p3(&u,&t);
                # ge_msub(&t,&u,&Bi[(-bslide[i])/2]);
                $u = self::ge_p1p1_to_p3($t);
                $t = self::ge_msub($t, $u, $Bi[$index]);
            }
            # ge_p1p1_to_p2(r,&t);
            $r = self::ge_p1p1_to_p2($t);
        }
        return $r;
    }

    /**
     * @internal You should not use this directly from another application
     *
     * @param string $a
     * @param ParagonIE_Sodium_Core_Curve25519_Ge_P3 $p
     * @return ParagonIE_Sodium_Core_Curve25519_Ge_P3
     * @throws SodiumException
     * @throws TypeError
     * @psalm-suppress MixedAssignment
     * @psalm-suppress MixedOperand
     */
    public static function ge_scalarmult($a, $p)
    {
        $e = array_fill(0, 64, 0);

        /** @var ParagonIE_Sodium_Core_Curve25519_Ge_Cached[] $pi */
        $pi = array();

        //        ge25519_p3_to_cached(&pi[1 - 1], p);   /* p */
        $pi[0] = self::ge_p3_to_cached($p);

        //        ge25519_p3_dbl(&t2, p);
        //        ge25519_p1p1_to_p3(&p2, &t2);
        //        ge25519_p3_to_cached(&pi[2 - 1], &p2); /* 2p = 2*p */
        $t2 = self::ge_p3_dbl($p);
        $p2 = self::ge_p1p1_to_p3($t2);
        $pi[1] = self::ge_p3_to_cached($p2);

        //        ge25519_add_cached(&t3, p, &pi[2 - 1]);
        //        ge25519_p1p1_to_p3(&p3, &t3);
        //        ge25519_p3_to_cached(&pi[3 - 1], &p3); /* 3p = 2p+p */
        $t3 = self::ge_add($p, $pi[1]);
        $p3 = self::ge_p1p1_to_p3($t3);
        $pi[2] = self::ge_p3_to_cached($p3);

        //        ge25519_p3_dbl(&t4, &p2);
        //        ge25519_p1p1_to_p3(&p4, &t4);
        //        ge25519_p3_to_cached(&pi[4 - 1], &p4); /* 4p = 2*2p */
        $t4 = self::ge_p3_dbl($p2);
        $p4 = self::ge_p1p1_to_p3($t4);
        $pi[3] = self::ge_p3_to_cached($p4);

        //        ge25519_add_cached(&t5, p, &pi[4 - 1]);
        //        ge25519_p1p1_to_p3(&p5, &t5);
        //        ge25519_p3_to_cached(&pi[5 - 1], &p5); /* 5p = 4p+p */
        $t5 = self::ge_add($p, $pi[3]);
        $p5 = self::ge_p1p1_to_p3($t5);
        $pi[4] = self::ge_p3_to_cached($p5);

        //        ge25519_p3_dbl(&t6, &p3);
        //        ge25519_p1p1_to_p3(&p6, &t6);
        //        ge25519_p3_to_cached(&pi[6 - 1], &p6); /* 6p = 2*3p */
        $t6 = self::ge_p3_dbl($p3);
        $p6 = self::ge_p1p1_to_p3($t6);
        $pi[5] = self::ge_p3_to_cached($p6);

        //        ge25519_add_cached(&t7, p, &pi[6 - 1]);
        //        ge25519_p1p1_to_p3(&p7, &t7);
        //        ge25519_p3_to_cached(&pi[7 - 1], &p7); /* 7p = 6p+p */
        $t7 = self::ge_add($p, $pi[5]);
        $p7 = self::ge_p1p1_to_p3($t7);
        $pi[6] = self::ge_p3_to_cached($p7);

        //        ge25519_p3_dbl(&t8, &p4);
        //        ge25519_p1p1_to_p3(&p8, &t8);
        //        ge25519_p3_to_cached(&pi[8 - 1], &p8); /* 8p = 2*4p */
        $t8 = self::ge_p3_dbl($p4);
        $p8 = self::ge_p1p1_to_p3($t8);
        $pi[7] = self::ge_p3_to_cached($p8);


        //        for (i = 0; i < 32; ++i) {
        //            e[2 * i + 0] = (a[i] >> 0) & 15;
        //            e[2 * i + 1] = (a[i] >> 4) & 15;
        //        }
        for ($i = 0; $i < 32; ++$i) {
            $e[($i << 1)    ] =  self::chrToInt($a[$i]) & 15;
            $e[($i << 1) + 1] = (self::chrToInt($a[$i]) >> 4) & 15;
        }
        //        /* each e[i] is between 0 and 15 */
        //        /* e[63] is between 0 and 7 */

        //        carry = 0;
        //        for (i = 0; i < 63; ++i) {
        //            e[i] += carry;
        //            carry = e[i] + 8;
        //            carry >>= 4;
        //            e[i] -= carry * ((signed char) 1 << 4);
        //        }
        $carry = 0;
        for ($i = 0; $i < 63; ++$i) {
            $e[$i] += $carry;
            $carry = $e[$i] + 8;
            $carry >>= 4;
            $e[$i] -= $carry << 4;
        }
        //        e[63] += carry;
        //        /* each e[i] is between -8 and 8 */
        $e[63] += $carry;

        //        ge25519_p3_0(h);
        $h = self::ge_p3_0();

        //        for (i = 63; i != 0; i--) {
        for ($i = 63; $i != 0; --$i) {
            // ge25519_cmov8_cached(&t, pi, e[i]);
            $t = self::ge_cmov8_cached($pi, $e[$i]);
            // ge25519_add_cached(&r, h, &t);
            $r = self::ge_add($h, $t);

            // ge25519_p1p1_to_p2(&s, &r);
            // ge25519_p2_dbl(&r, &s);
            // ge25519_p1p1_to_p2(&s, &r);
            // ge25519_p2_dbl(&r, &s);
            // ge25519_p1p1_to_p2(&s, &r);
            // ge25519_p2_dbl(&r, &s);
            // ge25519_p1p1_to_p2(&s, &r);
            // ge25519_p2_dbl(&r, &s);
            $s = self::ge_p1p1_to_p2($r);
            $r = self::ge_p2_dbl($s);
            $s = self::ge_p1p1_to_p2($r);
            $r = self::ge_p2_dbl($s);
            $s = self::ge_p1p1_to_p2($r);
            $r = self::ge_p2_dbl($s);
            $s = self::ge_p1p1_to_p2($r);
            $r = self::ge_p2_dbl($s);

            // ge25519_p1p1_to_p3(h, &r);  /* *16 */
            $h = self::ge_p1p1_to_p3($r); /* *16 */
        }

        //        ge25519_cmov8_cached(&t, pi, e[i]);
        //        ge25519_add_cached(&r, h, &t);
        //        ge25519_p1p1_to_p3(h, &r);
        $t = self::ge_cmov8_cached($pi, $e[0]);
        $r = self::ge_add($h, $t);
        return self::ge_p1p1_to_p3($r);
    }

    /**
     * @internal You should not use this directly from another application
     *
     * @param string $a
     * @return ParagonIE_Sodium_Core_Curve25519_Ge_P3
     * @throws SodiumException
     * @throws TypeError
     * @psalm-suppress MixedAssignment
     * @psalm-suppress MixedOperand
     */
    public static function ge_scalarmult_base($a)
    {
        /** @var array<int, int> $e */
        $e = array();
        $r = new ParagonIE_Sodium_Core_Curve25519_Ge_P1p1();

        for ($i = 0; $i < 32; ++$i) {
            $dbl = (int) $i << 1;
            $e[$dbl] = (int) self::chrToInt($a[$i]) & 15;
            $e[$dbl + 1] = (int) (self::chrToInt($a[$i]) >> 4) & 15;
        }

        $carry = 0;
        for ($i = 0; $i < 63; ++$i) {
            $e[$i] += $carry;
            $carry = $e[$i] + 8;
            $carry >>= 4;
            $e[$i] -= $carry << 4;
        }
        $e[63] += (int) $carry;

        $h = self::ge_p3_0();

        for ($i = 1; $i < 64; $i += 2) {
            $t = self::ge_select((int) floor($i / 2), (int) $e[$i]);
            $r = self::ge_madd($r, $h, $t);
            $h = self::ge_p1p1_to_p3($r);
        }

        $r = self::ge_p3_dbl($h);

        $s = self::ge_p1p1_to_p2($r);
        $r = self::ge_p2_dbl($s);
        $s = self::ge_p1p1_to_p2($r);
        $r = self::ge_p2_dbl($s);
        $s = self::ge_p1p1_to_p2($r);
        $r = self::ge_p2_dbl($s);

        $h = self::ge_p1p1_to_p3($r);

        for ($i = 0; $i < 64; $i += 2) {
            $t = self::ge_select($i >> 1, (int) $e[$i]);
            $r = self::ge_madd($r, $h, $t);
            $h = self::ge_p1p1_to_p3($r);
        }
        return $h;
    }

    /**
     * Calculates (ab + c) mod l
     * where l = 2^252 + 27742317777372353535851937790883648493
     *
     * @internal You should not use this directly from another application
     *
     * @param string $a
     * @param string $b
     * @param string $c
     * @return string
     * @throws TypeError
     */
    public static function sc_muladd($a, $b, $c)
    {
        $a0 = 2097151 & self::load_3(self::substr($a, 0, 3));
        $a1 = 2097151 & (self::load_4(self::substr($a, 2, 4)) >> 5);
        $a2 = 2097151 & (self::load_3(self::substr($a, 5, 3)) >> 2);
        $a3 = 2097151 & (self::load_4(self::substr($a, 7, 4)) >> 7);
        $a4 = 2097151 & (self::load_4(self::substr($a, 10, 4)) >> 4);
        $a5 = 2097151 & (self::load_3(self::substr($a, 13, 3)) >> 1);
        $a6 = 2097151 & (self::load_4(self::substr($a, 15, 4)) >> 6);
        $a7 = 2097151 & (self::load_3(self::substr($a, 18, 3)) >> 3);
        $a8 = 2097151 & self::load_3(self::substr($a, 21, 3));
        $a9 = 2097151 & (self::load_4(self::substr($a, 23, 4)) >> 5);
        $a10 = 2097151 & (self::load_3(self::substr($a, 26, 3)) >> 2);
        $a11 = (self::load_4(self::substr($a, 28, 4)) >> 7);

        $b0 = 2097151 & self::load_3(self::substr($b, 0, 3));
        $b1 = 2097151 & (self::load_4(self::substr($b, 2, 4)) >> 5);
        $b2 = 2097151 & (self::load_3(self::substr($b, 5, 3)) >> 2);
        $b3 = 2097151 & (self::load_4(self::substr($b, 7, 4)) >> 7);
        $b4 = 2097151 & (self::load_4(self::substr($b, 10, 4)) >> 4);
        $b5 = 2097151 & (self::load_3(self::substr($b, 13, 3)) >> 1);
        $b6 = 2097151 & (self::load_4(self::substr($b, 15, 4)) >> 6);
        $b7 = 2097151 & (self::load_3(self::substr($b, 18, 3)) >> 3);
        $b8 = 2097151 & self::load_3(self::substr($b, 21, 3));
        $b9 = 2097151 & (self::load_4(self::substr($b, 23, 4)) >> 5);
        $b10 = 2097151 & (self::load_3(self::substr($b, 26, 3)) >> 2);
        $b11 = (self::load_4(self::substr($b, 28, 4)) >> 7);

        $c0 = 2097151 & self::load_3(self::substr($c, 0, 3));
        $c1 = 2097151 & (self::load_4(self::substr($c, 2, 4)) >> 5);
        $c2 = 2097151 & (self::load_3(self::substr($c, 5, 3)) >> 2);
        $c3 = 2097151 & (self::load_4(self::substr($c, 7, 4)) >> 7);
        $c4 = 2097151 & (self::load_4(self::substr($c, 10, 4)) >> 4);
        $c5 = 2097151 & (self::load_3(self::substr($c, 13, 3)) >> 1);
        $c6 = 2097151 & (self::load_4(self::substr($c, 15, 4)) >> 6);
        $c7 = 2097151 & (self::load_3(self::substr($c, 18, 3)) >> 3);
        $c8 = 2097151 & self::load_3(self::substr($c, 21, 3));
        $c9 = 2097151 & (self::load_4(self::substr($c, 23, 4)) >> 5);
        $c10 = 2097151 & (self::load_3(self::substr($c, 26, 3)) >> 2);
        $c11 = (self::load_4(self::substr($c, 28, 4)) >> 7);

        /* Can't really avoid the pyramid here: */
        $s0 = $c0 + self::mul($a0, $b0, 24);
        $s1 = $c1 + self::mul($a0, $b1, 24) + self::mul($a1, $b0, 24);
        $s2 = $c2 + self::mul($a0, $b2, 24) + self::mul($a1, $b1, 24) + self::mul($a2, $b0, 24);
        $s3 = $c3 + self::mul($a0, $b3, 24) + self::mul($a1, $b2, 24) + self::mul($a2, $b1, 24) + self::mul($a3, $b0, 24);
        $s4 = $c4 + self::mul($a0, $b4, 24) + self::mul($a1, $b3, 24) + self::mul($a2, $b2, 24) + self::mul($a3, $b1, 24) +
               self::mul($a4, $b0, 24);
        $s5 = $c5 + self::mul($a0, $b5, 24) + self::mul($a1, $b4, 24) + self::mul($a2, $b3, 24) + self::mul($a3, $b2, 24) +
               self::mul($a4, $b1, 24) + self::mul($a5, $b0, 24);
        $s6 = $c6 + self::mul($a0, $b6, 24) + self::mul($a1, $b5, 24) + self::mul($a2, $b4, 24) + self::mul($a3, $b3, 24) +
               self::mul($a4, $b2, 24) + self::mul($a5, $b1, 24) + self::mul($a6, $b0, 24);
        $s7 = $c7 + self::mul($a0, $b7, 24) + self::mul($a1, $b6, 24) + self::mul($a2, $b5, 24) + self::mul($a3, $b4, 24) +
               self::mul($a4, $b3, 24) + self::mul($a5, $b2, 24) + self::mul($a6, $b1, 24) + self::mul($a7, $b0, 24);
        $s8 = $c8 + self::mul($a0, $b8, 24) + self::mul($a1, $b7, 24) + self::mul($a2, $b6, 24) + self::mul($a3, $b5, 24) +
               self::mul($a4, $b4, 24) + self::mul($a5, $b3, 24) + self::mul($a6, $b2, 24) + self::mul($a7, $b1, 24) +
               self::mul($a8, $b0, 24);
        $s9 = $c9 + self::mul($a0, $b9, 24) + self::mul($a1, $b8, 24) + self::mul($a2, $b7, 24) + self::mul($a3, $b6, 24) +
               self::mul($a4, $b5, 24) + self::mul($a5, $b4, 24) + self::mul($a6, $b3, 24) + self::mul($a7, $b2, 24) +
               self::mul($a8, $b1, 24) + self::mul($a9, $b0, 24);
        $s10 = $c10 + self::mul($a0, $b10, 24) + self::mul($a1, $b9, 24) + self::mul($a2, $b8, 24) + self::mul($a3, $b7, 24) +
               self::mul($a4, $b6, 24) + self::mul($a5, $b5, 24) + self::mul($a6, $b4, 24) + self::mul($a7, $b3, 24) +
               self::mul($a8, $b2, 24) + self::mul($a9, $b1, 24) + self::mul($a10, $b0, 24);
        $s11 = $c11 + self::mul($a0, $b11, 24) + self::mul($a1, $b10, 24) + self::mul($a2, $b9, 24) + self::mul($a3, $b8, 24) +
               self::mul($a4, $b7, 24) + self::mul($a5, $b6, 24) + self::mul($a6, $b5, 24) + self::mul($a7, $b4, 24) +
               self::mul($a8, $b3, 24) + self::mul($a9, $b2, 24) + self::mul($a10, $b1, 24) + self::mul($a11, $b0, 24);
        $s12 = self::mul($a1, $b11, 24) + self::mul($a2, $b10, 24) + self::mul($a3, $b9, 24) + self::mul($a4, $b8, 24) +
               self::mul($a5, $b7, 24) + self::mul($a6, $b6, 24) + self::mul($a7, $b5, 24) + self::mul($a8, $b4, 24) +
               self::mul($a9, $b3, 24) + self::mul($a10, $b2, 24) + self::mul($a11, $b1, 24);
        $s13 = self::mul($a2, $b11, 24) + self::mul($a3, $b10, 24) + self::mul($a4, $b9, 24) + self::mul($a5, $b8, 24) +
               self::mul($a6, $b7, 24) + self::mul($a7, $b6, 24) + self::mul($a8, $b5, 24) + self::mul($a9, $b4, 24) +
               self::mul($a10, $b3, 24) + self::mul($a11, $b2, 24);
        $s14 = self::mul($a3, $b11, 24) + self::mul($a4, $b10, 24) + self::mul($a5, $b9, 24) + self::mul($a6, $b8, 24) +
               self::mul($a7, $b7, 24) + self::mul($a8, $b6, 24) + self::mul($a9, $b5, 24) + self::mul($a10, $b4, 24) +
               self::mul($a11, $b3, 24);
        $s15 = self::mul($a4, $b11, 24) + self::mul($a5, $b10, 24) + self::mul($a6, $b9, 24) + self::mul($a7, $b8, 24) +
               self::mul($a8, $b7, 24) + self::mul($a9, $b6, 24) + self::mul($a10, $b5, 24) + self::mul($a11, $b4, 24);
        $s16 = self::mul($a5, $b11, 24) + self::mul($a6, $b10, 24) + self::mul($a7, $b9, 24) + self::mul($a8, $b8, 24) +
               self::mul($a9, $b7, 24) + self::mul($a10, $b6, 24) + self::mul($a11, $b5, 24);
        $s17 = self::mul($a6, $b11, 24) + self::mul($a7, $b10, 24) + self::mul($a8, $b9, 24) + self::mul($a9, $b8, 24) +
               self::mul($a10, $b7, 24) + self::mul($a11, $b6, 24);
        $s18 = self::mul($a7, $b11, 24) + self::mul($a8, $b10, 24) + self::mul($a9, $b9, 24) + self::mul($a10, $b8, 24) +
               self::mul($a11, $b7, 24);
        $s19 = self::mul($a8, $b11, 24) + self::mul($a9, $b10, 24) + self::mul($a10, $b9, 24) + self::mul($a11, $b8, 24);
        $s20 = self::mul($a9, $b11, 24) + self::mul($a10, $b10, 24) + self::mul($a11, $b9, 24);
        $s21 = self::mul($a10, $b11, 24) + self::mul($a11, $b10, 24);
        $s22 = self::mul($a11, $b11, 24);
        $s23 = 0;

        $carry0 = ($s0 + (1 << 20)) >> 21;
        $s1 += $carry0;
        $s0 -= $carry0 << 21;
        $carry2 = ($s2 + (1 << 20)) >> 21;
        $s3 += $carry2;
        $s2 -= $carry2 << 21;
        $carry4 = ($s4 + (1 << 20)) >> 21;
        $s5 += $carry4;
        $s4 -= $carry4 << 21;
        $carry6 = ($s6 + (1 << 20)) >> 21;
        $s7 += $carry6;
        $s6 -= $carry6 << 21;
        $carry8 = ($s8 + (1 << 20)) >> 21;
        $s9 += $carry8;
        $s8 -= $carry8 << 21;
        $carry10 = ($s10 + (1 << 20)) >> 21;
        $s11 += $carry10;
        $s10 -= $carry10 << 21;
        $carry12 = ($s12 + (1 << 20)) >> 21;
        $s13 += $carry12;
        $s12 -= $carry12 << 21;
        $carry14 = ($s14 + (1 << 20)) >> 21;
        $s15 += $carry14;
        $s14 -= $carry14 << 21;
        $carry16 = ($s16 + (1 << 20)) >> 21;
        $s17 += $carry16;
        $s16 -= $carry16 << 21;
        $carry18 = ($s18 + (1 << 20)) >> 21;
        $s19 += $carry18;
        $s18 -= $carry18 << 21;
        $carry20 = ($s20 + (1 << 20)) >> 21;
        $s21 += $carry20;
        $s20 -= $carry20 << 21;
        $carry22 = ($s22 + (1 << 20)) >> 21;
        $s23 += $carry22;
        $s22 -= $carry22 << 21;

        $carry1 = ($s1 + (1 << 20)) >> 21;
        $s2 += $carry1;
        $s1 -= $carry1 << 21;
        $carry3 = ($s3 + (1 << 20)) >> 21;
        $s4 += $carry3;
        $s3 -= $carry3 << 21;
        $carry5 = ($s5 + (1 << 20)) >> 21;
        $s6 += $carry5;
        $s5 -= $carry5 << 21;
        $carry7 = ($s7 + (1 << 20)) >> 21;
        $s8 += $carry7;
        $s7 -= $carry7 << 21;
        $carry9 = ($s9 + (1 << 20)) >> 21;
        $s10 += $carry9;
        $s9 -= $carry9 << 21;
        $carry11 = ($s11 + (1 << 20)) >> 21;
        $s12 += $carry11;
        $s11 -= $carry11 << 21;
        $carry13 = ($s13 + (1 << 20)) >> 21;
        $s14 += $carry13;
        $s13 -= $carry13 << 21;
        $carry15 = ($s15 + (1 << 20)) >> 21;
        $s16 += $carry15;
        $s15 -= $carry15 << 21;
        $carry17 = ($s17 + (1 << 20)) >> 21;
        $s18 += $carry17;
        $s17 -= $carry17 << 21;
        $carry19 = ($s19 + (1 << 20)) >> 21;
        $s20 += $carry19;
        $s19 -= $carry19 << 21;
        $carry21 = ($s21 + (1 << 20)) >> 21;
        $s22 += $carry21;
        $s21 -= $carry21 << 21;

        $s11 += self::mul($s23, 666643, 20);
        $s12 += self::mul($s23, 470296, 19);
        $s13 += self::mul($s23, 654183, 20);
        $s14 -= self::mul($s23, 997805, 20);
        $s15 += self::mul($s23, 136657, 18);
        $s16 -= self::mul($s23, 683901, 20);

        $s10 += self::mul($s22, 666643, 20);
        $s11 += self::mul($s22, 470296, 19);
        $s12 += self::mul($s22, 654183, 20);
        $s13 -= self::mul($s22, 997805, 20);
        $s14 += self::mul($s22, 136657, 18);
        $s15 -= self::mul($s22, 683901, 20);

        $s9  += self::mul($s21,  666643, 20);
        $s10 += self::mul($s21,  470296, 19);
        $s11 += self::mul($s21,  654183, 20);
        $s12 -= self::mul($s21,  997805, 20);
        $s13 += self::mul($s21,  136657, 18);
        $s14 -= self::mul($s21,  683901, 20);

        $s8  += self::mul($s20,  666643, 20);
        $s9  += self::mul($s20,  470296, 19);
        $s10 += self::mul($s20,  654183, 20);
        $s11 -= self::mul($s20,  997805, 20);
        $s12 += self::mul($s20,  136657, 18);
        $s13 -= self::mul($s20,  683901, 20);

        $s7  += self::mul($s19,  666643, 20);
        $s8  += self::mul($s19,  470296, 19);
        $s9  += self::mul($s19,  654183, 20);
        $s10 -= self::mul($s19,  997805, 20);
        $s11 += self::mul($s19,  136657, 18);
        $s12 -= self::mul($s19,  683901, 20);

        $s6  += self::mul($s18,  666643, 20);
        $s7  += self::mul($s18,  470296, 19);
        $s8  += self::mul($s18,  654183, 20);
        $s9  -= self::mul($s18,  997805, 20);
        $s10 += self::mul($s18,  136657, 18);
        $s11 -= self::mul($s18,  683901, 20);

        $carry6 = ($s6 + (1 << 20)) >> 21;
        $s7 += $carry6;
        $s6 -= $carry6 << 21;
        $carry8 = ($s8 + (1 << 20)) >> 21;
        $s9 += $carry8;
        $s8 -= $carry8 << 21;
        $carry10 = ($s10 + (1 << 20)) >> 21;
        $s11 += $carry10;
        $s10 -= $carry10 << 21;
        $carry12 = ($s12 + (1 << 20)) >> 21;
        $s13 += $carry12;
        $s12 -= $carry12 << 21;
        $carry14 = ($s14 + (1 << 20)) >> 21;
        $s15 += $carry14;
        $s14 -= $carry14 << 21;
        $carry16 = ($s16 + (1 << 20)) >> 21;
        $s17 += $carry16;
        $s16 -= $carry16 << 21;

        $carry7 = ($s7 + (1 << 20)) >> 21;
        $s8 += $carry7;
        $s7 -= $carry7 << 21;
        $carry9 = ($s9 + (1 << 20)) >> 21;
        $s10 += $carry9;
        $s9 -= $carry9 << 21;
        $carry11 = ($s11 + (1 << 20)) >> 21;
        $s12 += $carry11;
        $s11 -= $carry11 << 21;
        $carry13 = ($s13 + (1 << 20)) >> 21;
        $s14 += $carry13;
        $s13 -= $carry13 << 21;
        $carry15 = ($s15 + (1 << 20)) >> 21;
        $s16 += $carry15;
        $s15 -= $carry15 << 21;

        $s5  += self::mul($s17,  666643, 20);
        $s6  += self::mul($s17,  470296, 19);
        $s7  += self::mul($s17,  654183, 20);
        $s8  -= self::mul($s17,  997805, 20);
        $s9  += self::mul($s17,  136657, 18);
        $s10 -= self::mul($s17,  683901, 20);

        $s4 += self::mul($s16,  666643, 20);
        $s5 += self::mul($s16,  470296, 19);
        $s6 += self::mul($s16,  654183, 20);
        $s7 -= self::mul($s16,  997805, 20);
        $s8 += self::mul($s16,  136657, 18);
        $s9 -= self::mul($s16,  683901, 20);

        $s3 += self::mul($s15,  666643, 20);
        $s4 += self::mul($s15,  470296, 19);
        $s5 += self::mul($s15,  654183, 20);
        $s6 -= self::mul($s15,  997805, 20);
        $s7 += self::mul($s15,  136657, 18);
        $s8 -= self::mul($s15,  683901, 20);

        $s2 += self::mul($s14,  666643, 20);
        $s3 += self::mul($s14,  470296, 19);
        $s4 += self::mul($s14,  654183, 20);
        $s5 -= self::mul($s14,  997805, 20);
        $s6 += self::mul($s14,  136657, 18);
        $s7 -= self::mul($s14,  683901, 20);

        $s1 += self::mul($s13,  666643, 20);
        $s2 += self::mul($s13,  470296, 19);
        $s3 += self::mul($s13,  654183, 20);
        $s4 -= self::mul($s13,  997805, 20);
        $s5 += self::mul($s13,  136657, 18);
        $s6 -= self::mul($s13,  683901, 20);

        $s0 += self::mul($s12,  666643, 20);
        $s1 += self::mul($s12,  470296, 19);
        $s2 += self::mul($s12,  654183, 20);
        $s3 -= self::mul($s12,  997805, 20);
        $s4 += self::mul($s12,  136657, 18);
        $s5 -= self::mul($s12,  683901, 20);
        $s12 = 0;

        $carry0 = ($s0 + (1 << 20)) >> 21;
        $s1 += $carry0;
        $s0 -= $carry0 << 21;
        $carry2 = ($s2 + (1 << 20)) >> 21;
        $s3 += $carry2;
        $s2 -= $carry2 << 21;
        $carry4 = ($s4 + (1 << 20)) >> 21;
        $s5 += $carry4;
        $s4 -= $carry4 << 21;
        $carry6 = ($s6 + (1 << 20)) >> 21;
        $s7 += $carry6;
        $s6 -= $carry6 << 21;
        $carry8 = ($s8 + (1 << 20)) >> 21;
        $s9 += $carry8;
        $s8 -= $carry8 << 21;
        $carry10 = ($s10 + (1 << 20)) >> 21;
        $s11 += $carry10;
        $s10 -= $carry10 << 21;

        $carry1 = ($s1 + (1 << 20)) >> 21;
        $s2 += $carry1;
        $s1 -= $carry1 << 21;
        $carry3 = ($s3 + (1 << 20)) >> 21;
        $s4 += $carry3;
        $s3 -= $carry3 << 21;
        $carry5 = ($s5 + (1 << 20)) >> 21;
        $s6 += $carry5;
        $s5 -= $carry5 << 21;
        $carry7 = ($s7 + (1 << 20)) >> 21;
        $s8 += $carry7;
        $s7 -= $carry7 << 21;
        $carry9 = ($s9 + (1 << 20)) >> 21;
        $s10 += $carry9;
        $s9 -= $carry9 << 21;
        $carry11 = ($s11 + (1 << 20)) >> 21;
        $s12 += $carry11;
        $s11 -= $carry11 << 21;

        $s0 += self::mul($s12,  666643, 20);
        $s1 += self::mul($s12,  470296, 19);
        $s2 += self::mul($s12,  654183, 20);
        $s3 -= self::mul($s12,  997805, 20);
        $s4 += self::mul($s12,  136657, 18);
        $s5 -= self::mul($s12,  683901, 20);
        $s12 = 0;

        $carry0 = $s0 >> 21;
        $s1 += $carry0;
        $s0 -= $carry0 << 21;
        $carry1 = $s1 >> 21;
        $s2 += $carry1;
        $s1 -= $carry1 << 21;
        $carry2 = $s2 >> 21;
        $s3 += $carry2;
        $s2 -= $carry2 << 21;
        $carry3 = $s3 >> 21;
        $s4 += $carry3;
        $s3 -= $carry3 << 21;
        $carry4 = $s4 >> 21;
        $s5 += $carry4;
        $s4 -= $carry4 << 21;
        $carry5 = $s5 >> 21;
        $s6 += $carry5;
        $s5 -= $carry5 << 21;
        $carry6 = $s6 >> 21;
        $s7 += $carry6;
        $s6 -= $carry6 << 21;
        $carry7 = $s7 >> 21;
        $s8 += $carry7;
        $s7 -= $carry7 << 21;
        $carry8 = $s8 >> 21;
        $s9 += $carry8;
        $s8 -= $carry8 << 21;
        $carry9 = $s9 >> 21;
        $s10 += $carry9;
        $s9 -= $carry9 << 21;
        $carry10 = $s10 >> 21;
        $s11 += $carry10;
        $s10 -= $carry10 << 21;
        $carry11 = $s11 >> 21;
        $s12 += $carry11;
        $s11 -= $carry11 << 21;

        $s0 += self::mul($s12,  666643, 20);
        $s1 += self::mul($s12,  470296, 19);
        $s2 += self::mul($s12,  654183, 20);
        $s3 -= self::mul($s12,  997805, 20);
        $s4 += self::mul($s12,  136657, 18);
        $s5 -= self::mul($s12,  683901, 20);

        $carry0 = $s0 >> 21;
        $s1 += $carry0;
        $s0 -= $carry0 << 21;
        $carry1 = $s1 >> 21;
        $s2 += $carry1;
        $s1 -= $carry1 << 21;
        $carry2 = $s2 >> 21;
        $s3 += $carry2;
        $s2 -= $carry2 << 21;
        $carry3 = $s3 >> 21;
        $s4 += $carry3;
        $s3 -= $carry3 << 21;
        $carry4 = $s4 >> 21;
        $s5 += $carry4;
        $s4 -= $carry4 << 21;
        $carry5 = $s5 >> 21;
        $s6 += $carry5;
        $s5 -= $carry5 << 21;
        $carry6 = $s6 >> 21;
        $s7 += $carry6;
        $s6 -= $carry6 << 21;
        $carry7 = $s7 >> 21;
        $s8 += $carry7;
        $s7 -= $carry7 << 21;
        $carry8 = $s8 >> 21;
        $s9 += $carry8;
        $s8 -= $carry8 << 21;
        $carry9 = $s9 >> 21;
        $s10 += $carry9;
        $s9 -= $carry9 << 21;
        $carry10 = $s10 >> 21;
        $s11 += $carry10;
        $s10 -= $carry10 << 21;

        /**
         * @var array<int, int>
         */
        $arr = array(
            (int) (0xff & ($s0 >> 0)),
            (int) (0xff & ($s0 >> 8)),
            (int) (0xff & (($s0 >> 16) | $s1 << 5)),
            (int) (0xff & ($s1 >> 3)),
            (int) (0xff & ($s1 >> 11)),
            (int) (0xff & (($s1 >> 19) | $s2 << 2)),
            (int) (0xff & ($s2 >> 6)),
            (int) (0xff & (($s2 >> 14) | $s3 << 7)),
            (int) (0xff & ($s3 >> 1)),
            (int) (0xff & ($s3 >> 9)),
            (int) (0xff & (($s3 >> 17) | $s4 << 4)),
            (int) (0xff & ($s4 >> 4)),
            (int) (0xff & ($s4 >> 12)),
            (int) (0xff & (($s4 >> 20) | $s5 << 1)),
            (int) (0xff & ($s5 >> 7)),
            (int) (0xff & (($s5 >> 15) | $s6 << 6)),
            (int) (0xff & ($s6 >> 2)),
            (int) (0xff & ($s6 >> 10)),
            (int) (0xff & (($s6 >> 18) | $s7 << 3)),
            (int) (0xff & ($s7 >> 5)),
            (int) (0xff & ($s7 >> 13)),
            (int) (0xff & ($s8 >> 0)),
            (int) (0xff & ($s8 >> 8)),
            (int) (0xff & (($s8 >> 16) | $s9 << 5)),
            (int) (0xff & ($s9 >> 3)),
            (int) (0xff & ($s9 >> 11)),
            (int) (0xff & (($s9 >> 19) | $s10 << 2)),
            (int) (0xff & ($s10 >> 6)),
            (int) (0xff & (($s10 >> 14) | $s11 << 7)),
            (int) (0xff & ($s11 >> 1)),
            (int) (0xff & ($s11 >> 9)),
            0xff & ($s11 >> 17)
        );
        return self::intArrayToString($arr);
    }

    /**
     * @internal You should not use this directly from another application
     *
     * @param string $s
     * @return string
     * @throws TypeError
     */
    public static function sc_reduce($s)
    {
        $s0 = 2097151 & self::load_3(self::substr($s, 0, 3));
        $s1 = 2097151 & (self::load_4(self::substr($s, 2, 4)) >> 5);
        $s2 = 2097151 & (self::load_3(self::substr($s, 5, 3)) >> 2);
        $s3 = 2097151 & (self::load_4(self::substr($s, 7, 4)) >> 7);
        $s4 = 2097151 & (self::load_4(self::substr($s, 10, 4)) >> 4);
        $s5 = 2097151 & (self::load_3(self::substr($s, 13, 3)) >> 1);
        $s6 = 2097151 & (self::load_4(self::substr($s, 15, 4)) >> 6);
        $s7 = 2097151 & (self::load_3(self::substr($s, 18, 4)) >> 3);
        $s8 = 2097151 & self::load_3(self::substr($s, 21, 3));
        $s9 = 2097151 & (self::load_4(self::substr($s, 23, 4)) >> 5);
        $s10 = 2097151 & (self::load_3(self::substr($s, 26, 3)) >> 2);
        $s11 = 2097151 & (self::load_4(self::substr($s, 28, 4)) >> 7);
        $s12 = 2097151 & (self::load_4(self::substr($s, 31, 4)) >> 4);
        $s13 = 2097151 & (self::load_3(self::substr($s, 34, 3)) >> 1);
        $s14 = 2097151 & (self::load_4(self::substr($s, 36, 4)) >> 6);
        $s15 = 2097151 & (self::load_3(self::substr($s, 39, 4)) >> 3);
        $s16 = 2097151 & self::load_3(self::substr($s, 42, 3));
        $s17 = 2097151 & (self::load_4(self::substr($s, 44, 4)) >> 5);
        $s18 = 2097151 & (self::load_3(self::substr($s, 47, 3)) >> 2);
        $s19 = 2097151 & (self::load_4(self::substr($s, 49, 4)) >> 7);
        $s20 = 2097151 & (self::load_4(self::substr($s, 52, 4)) >> 4);
        $s21 = 2097151 & (self::load_3(self::substr($s, 55, 3)) >> 1);
        $s22 = 2097151 & (self::load_4(self::substr($s, 57, 4)) >> 6);
        $s23 = 0x1fffffff & (self::load_4(self::substr($s, 60, 4)) >> 3);

        $s11 += self::mul($s23,  666643, 20);
        $s12 += self::mul($s23,  470296, 19);
        $s13 += self::mul($s23,  654183, 20);
        $s14 -= self::mul($s23,  997805, 20);
        $s15 += self::mul($s23,  136657, 18);
        $s16 -= self::mul($s23,  683901, 20);

        $s10 += self::mul($s22,  666643, 20);
        $s11 += self::mul($s22,  470296, 19);
        $s12 += self::mul($s22,  654183, 20);
        $s13 -= self::mul($s22,  997805, 20);
        $s14 += self::mul($s22,  136657, 18);
        $s15 -= self::mul($s22,  683901, 20);

        $s9  += self::mul($s21,  666643, 20);
        $s10 += self::mul($s21,  470296, 19);
        $s11 += self::mul($s21,  654183, 20);
        $s12 -= self::mul($s21,  997805, 20);
        $s13 += self::mul($s21,  136657, 18);
        $s14 -= self::mul($s21,  683901, 20);

        $s8  += self::mul($s20,  666643, 20);
        $s9  += self::mul($s20,  470296, 19);
        $s10 += self::mul($s20,  654183, 20);
        $s11 -= self::mul($s20,  997805, 20);
        $s12 += self::mul($s20,  136657, 18);
        $s13 -= self::mul($s20,  683901, 20);

        $s7  += self::mul($s19,  666643, 20);
        $s8  += self::mul($s19,  470296, 19);
        $s9  += self::mul($s19,  654183, 20);
        $s10 -= self::mul($s19,  997805, 20);
        $s11 += self::mul($s19,  136657, 18);
        $s12 -= self::mul($s19,  683901, 20);

        $s6  += self::mul($s18,  666643, 20);
        $s7  += self::mul($s18,  470296, 19);
        $s8  += self::mul($s18,  654183, 20);
        $s9  -= self::mul($s18,  997805, 20);
        $s10 += self::mul($s18,  136657, 18);
        $s11 -= self::mul($s18,  683901, 20);

        $carry6 = ($s6 + (1 << 20)) >> 21;
        $s7 += $carry6;
        $s6 -= $carry6 << 21;
        $carry8 = ($s8 + (1 << 20)) >> 21;
        $s9 += $carry8;
        $s8 -= $carry8 << 21;
        $carry10 = ($s10 + (1 << 20)) >> 21;
        $s11 += $carry10;
        $s10 -= $carry10 << 21;
        $carry12 = ($s12 + (1 << 20)) >> 21;
        $s13 += $carry12;
        $s12 -= $carry12 << 21;
        $carry14 = ($s14 + (1 << 20)) >> 21;
        $s15 += $carry14;
        $s14 -= $carry14 << 21;
        $carry16 = ($s16 + (1 << 20)) >> 21;
        $s17 += $carry16;
        $s16 -= $carry16 << 21;

        $carry7 = ($s7 + (1 << 20)) >> 21;
        $s8 += $carry7;
        $s7 -= $carry7 << 21;
        $carry9 = ($s9 + (1 << 20)) >> 21;
        $s10 += $carry9;
        $s9 -= $carry9 << 21;
        $carry11 = ($s11 + (1 << 20)) >> 21;
        $s12 += $carry11;
        $s11 -= $carry11 << 21;
        $carry13 = ($s13 + (1 << 20)) >> 21;
        $s14 += $carry13;
        $s13 -= $carry13 << 21;
        $carry15 = ($s15 + (1 << 20)) >> 21;
        $s16 += $carry15;
        $s15 -= $carry15 << 21;

        $s5  += self::mul($s17,  666643, 20);
        $s6  += self::mul($s17,  470296, 19);
        $s7  += self::mul($s17,  654183, 20);
        $s8  -= self::mul($s17,  997805, 20);
        $s9  += self::mul($s17,  136657, 18);
        $s10 -= self::mul($s17,  683901, 20);

        $s4 += self::mul($s16,  666643, 20);
        $s5 += self::mul($s16,  470296, 19);
        $s6 += self::mul($s16,  654183, 20);
        $s7 -= self::mul($s16,  997805, 20);
        $s8 += self::mul($s16,  136657, 18);
        $s9 -= self::mul($s16,  683901, 20);

        $s3 += self::mul($s15,  666643, 20);
        $s4 += self::mul($s15,  470296, 19);
        $s5 += self::mul($s15,  654183, 20);
        $s6 -= self::mul($s15,  997805, 20);
        $s7 += self::mul($s15,  136657, 18);
        $s8 -= self::mul($s15,  683901, 20);

        $s2 += self::mul($s14,  666643, 20);
        $s3 += self::mul($s14,  470296, 19);
        $s4 += self::mul($s14,  654183, 20);
        $s5 -= self::mul($s14,  997805, 20);
        $s6 += self::mul($s14,  136657, 18);
        $s7 -= self::mul($s14,  683901, 20);

        $s1 += self::mul($s13,  666643, 20);
        $s2 += self::mul($s13,  470296, 19);
        $s3 += self::mul($s13,  654183, 20);
        $s4 -= self::mul($s13,  997805, 20);
        $s5 += self::mul($s13,  136657, 18);
        $s6 -= self::mul($s13,  683901, 20);

        $s0 += self::mul($s12,  666643, 20);
        $s1 += self::mul($s12,  470296, 19);
        $s2 += self::mul($s12,  654183, 20);
        $s3 -= self::mul($s12,  997805, 20);
        $s4 += self::mul($s12,  136657, 18);
        $s5 -= self::mul($s12,  683901, 20);
        $s12 = 0;

        $carry0 = ($s0 + (1 << 20)) >> 21;
        $s1 += $carry0;
        $s0 -= $carry0 << 21;
        $carry2 = ($s2 + (1 << 20)) >> 21;
        $s3 += $carry2;
        $s2 -= $carry2 << 21;
        $carry4 = ($s4 + (1 << 20)) >> 21;
        $s5 += $carry4;
        $s4 -= $carry4 << 21;
        $carry6 = ($s6 + (1 << 20)) >> 21;
        $s7 += $carry6;
        $s6 -= $carry6 << 21;
        $carry8 = ($s8 + (1 << 20)) >> 21;
        $s9 += $carry8;
        $s8 -= $carry8 << 21;
        $carry10 = ($s10 + (1 << 20)) >> 21;
        $s11 += $carry10;
        $s10 -= $carry10 << 21;

        $carry1 = ($s1 + (1 << 20)) >> 21;
        $s2 += $carry1;
        $s1 -= $carry1 << 21;
        $carry3 = ($s3 + (1 << 20)) >> 21;
        $s4 += $carry3;
        $s3 -= $carry3 << 21;
        $carry5 = ($s5 + (1 << 20)) >> 21;
        $s6 += $carry5;
        $s5 -= $carry5 << 21;
        $carry7 = ($s7 + (1 << 20)) >> 21;
        $s8 += $carry7;
        $s7 -= $carry7 << 21;
        $carry9 = ($s9 + (1 << 20)) >> 21;
        $s10 += $carry9;
        $s9 -= $carry9 << 21;
        $carry11 = ($s11 + (1 << 20)) >> 21;
        $s12 += $carry11;
        $s11 -= $carry11 << 21;

        $s0 += self::mul($s12,  666643, 20);
        $s1 += self::mul($s12,  470296, 19);
        $s2 += self::mul($s12,  654183, 20);
        $s3 -= self::mul($s12,  997805, 20);
        $s4 += self::mul($s12,  136657, 18);
        $s5 -= self::mul($s12,  683901, 20);
        $s12 = 0;

        $carry0 = $s0 >> 21;
        $s1 += $carry0;
        $s0 -= $carry0 << 21;
        $carry1 = $s1 >> 21;
        $s2 += $carry1;
        $s1 -= $carry1 << 21;
        $carry2 = $s2 >> 21;
        $s3 += $carry2;
        $s2 -= $carry2 << 21;
        $carry3 = $s3 >> 21;
        $s4 += $carry3;
        $s3 -= $carry3 << 21;
        $carry4 = $s4 >> 21;
        $s5 += $carry4;
        $s4 -= $carry4 << 21;
        $carry5 = $s5 >> 21;
        $s6 += $carry5;
        $s5 -= $carry5 << 21;
        $carry6 = $s6 >> 21;
        $s7 += $carry6;
        $s6 -= $carry6 << 21;
        $carry7 = $s7 >> 21;
        $s8 += $carry7;
        $s7 -= $carry7 << 21;
        $carry8 = $s8 >> 21;
        $s9 += $carry8;
        $s8 -= $carry8 << 21;
        $carry9 = $s9 >> 21;
        $s10 += $carry9;
        $s9 -= $carry9 << 21;
        $carry10 = $s10 >> 21;
        $s11 += $carry10;
        $s10 -= $carry10 << 21;
        $carry11 = $s11 >> 21;
        $s12 += $carry11;
        $s11 -= $carry11 << 21;

        $s0 += self::mul($s12,  666643, 20);
        $s1 += self::mul($s12,  470296, 19);
        $s2 += self::mul($s12,  654183, 20);
        $s3 -= self::mul($s12,  997805, 20);
        $s4 += self::mul($s12,  136657, 18);
        $s5 -= self::mul($s12,  683901, 20);

        $carry0 = $s0 >> 21;
        $s1 += $carry0;
        $s0 -= $carry0 << 21;
        $carry1 = $s1 >> 21;
        $s2 += $carry1;
        $s1 -= $carry1 << 21;
        $carry2 = $s2 >> 21;
        $s3 += $carry2;
        $s2 -= $carry2 << 21;
        $carry3 = $s3 >> 21;
        $s4 += $carry3;
        $s3 -= $carry3 << 21;
        $carry4 = $s4 >> 21;
        $s5 += $carry4;
        $s4 -= $carry4 << 21;
        $carry5 = $s5 >> 21;
        $s6 += $carry5;
        $s5 -= $carry5 << 21;
        $carry6 = $s6 >> 21;
        $s7 += $carry6;
        $s6 -= $carry6 << 21;
        $carry7 = $s7 >> 21;
        $s8 += $carry7;
        $s7 -= $carry7 << 21;
        $carry8 = $s8 >> 21;
        $s9 += $carry8;
        $s8 -= $carry8 << 21;
        $carry9 = $s9 >> 21;
        $s10 += $carry9;
        $s9 -= $carry9 << 21;
        $carry10 = $s10 >> 21;
        $s11 += $carry10;
        $s10 -= $carry10 << 21;

        /**
         * @var array<int, int>
         */
        $arr = array(
            (int) ($s0 >> 0),
            (int) ($s0 >> 8),
            (int) (($s0 >> 16) | $s1 << 5),
            (int) ($s1 >> 3),
            (int) ($s1 >> 11),
            (int) (($s1 >> 19) | $s2 << 2),
            (int) ($s2 >> 6),
            (int) (($s2 >> 14) | $s3 << 7),
            (int) ($s3 >> 1),
            (int) ($s3 >> 9),
            (int) (($s3 >> 17) | $s4 << 4),
            (int) ($s4 >> 4),
            (int) ($s4 >> 12),
            (int) (($s4 >> 20) | $s5 << 1),
            (int) ($s5 >> 7),
            (int) (($s5 >> 15) | $s6 << 6),
            (int) ($s6 >> 2),
            (int) ($s6 >> 10),
            (int) (($s6 >> 18) | $s7 << 3),
            (int) ($s7 >> 5),
            (int) ($s7 >> 13),
            (int) ($s8 >> 0),
            (int) ($s8 >> 8),
            (int) (($s8 >> 16) | $s9 << 5),
            (int) ($s9 >> 3),
            (int) ($s9 >> 11),
            (int) (($s9 >> 19) | $s10 << 2),
            (int) ($s10 >> 6),
            (int) (($s10 >> 14) | $s11 << 7),
            (int) ($s11 >> 1),
            (int) ($s11 >> 9),
            (int) $s11 >> 17
        );
        return self::intArrayToString($arr);
    }

    /**
     * multiply by the order of the main subgroup l = 2^252+27742317777372353535851937790883648493
     *
     * @param ParagonIE_Sodium_Core_Curve25519_Ge_P3 $A
     * @return ParagonIE_Sodium_Core_Curve25519_Ge_P3
     */
    public static function ge_mul_l(ParagonIE_Sodium_Core_Curve25519_Ge_P3 $A)
    {
        $aslide = array(
            13, 0, 0, 0, 0, -1, 0, 0, 0, 0, -11, 0, 0, 0, 0, 0, 0, -5, 0, 0, 0,
            0, 0, 0, -3, 0, 0, 0, 0, -13, 0, 0, 0, 0, 7, 0, 0, 0, 0, 0, 3, 0,
            0, 0, 0, -13, 0, 0, 0, 0, 5, 0, 0, 0, 0, 0, 0, 0, 0, 11, 0, 0, 0,
            0, 0, 11, 0, 0, 0, 0, -13, 0, 0, 0, 0, 0, 0, -3, 0, 0, 0, 0, 0, -1,
            0, 0, 0, 0, 3, 0, 0, 0, 0, -11, 0, 0, 0, 0, 0, 0, 0, 15, 0, 0, 0,
            0, 0, -1, 0, 0, 0, 0, -1, 0, 0, 0, 0, 7, 0, 0, 0, 0, 5, 0, 0, 0, 0,
            0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
            0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
            0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
            0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
            0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
            0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1
        );

        /** @var array<int, ParagonIE_Sodium_Core_Curve25519_Ge_Cached> $Ai size 8 */
        $Ai = array();

        # ge_p3_to_cached(&Ai[0], A);
        $Ai[0] = self::ge_p3_to_cached($A);
        # ge_p3_dbl(&t, A);
        $t = self::ge_p3_dbl($A);
        # ge_p1p1_to_p3(&A2, &t);
        $A2 = self::ge_p1p1_to_p3($t);

        for ($i = 1; $i < 8; ++$i) {
            # ge_add(&t, &A2, &Ai[0]);
            $t = self::ge_add($A2, $Ai[$i - 1]);
            # ge_p1p1_to_p3(&u, &t);
            $u = self::ge_p1p1_to_p3($t);
            # ge_p3_to_cached(&Ai[i], &u);
            $Ai[$i] = self::ge_p3_to_cached($u);
        }

        $r = self::ge_p3_0();
        for ($i = 252; $i >= 0; --$i) {
            $t = self::ge_p3_dbl($r);
            if ($aslide[$i] > 0) {
                # ge_p1p1_to_p3(&u, &t);
                $u = self::ge_p1p1_to_p3($t);
                # ge_add(&t, &u, &Ai[aslide[i] / 2]);
                $t = self::ge_add($u, $Ai[(int)($aslide[$i] / 2)]);
            } elseif ($aslide[$i] < 0) {
                # ge_p1p1_to_p3(&u, &t);
                $u = self::ge_p1p1_to_p3($t);
                # ge_sub(&t, &u, &Ai[(-aslide[i]) / 2]);
                $t = self::ge_sub($u, $Ai[(int)(-$aslide[$i] / 2)]);
            }
        }

        # ge_p1p1_to_p3(r, &t);
        return self::ge_p1p1_to_p3($t);
    }

    /**
     * @param string $a
     * @param string $b
     * @return string
     */
    public static function sc25519_mul($a, $b)
    {
        //    int64_t a0  = 2097151 & load_3(a);
        //    int64_t a1  = 2097151 & (load_4(a + 2) >> 5);
        //    int64_t a2  = 2097151 & (load_3(a + 5) >> 2);
        //    int64_t a3  = 2097151 & (load_4(a + 7) >> 7);
        //    int64_t a4  = 2097151 & (load_4(a + 10) >> 4);
        //    int64_t a5  = 2097151 & (load_3(a + 13) >> 1);
        //    int64_t a6  = 2097151 & (load_4(a + 15) >> 6);
        //    int64_t a7  = 2097151 & (load_3(a + 18) >> 3);
        //    int64_t a8  = 2097151 & load_3(a + 21);
        //    int64_t a9  = 2097151 & (load_4(a + 23) >> 5);
        //    int64_t a10 = 2097151 & (load_3(a + 26) >> 2);
        //    int64_t a11 = (load_4(a + 28) >> 7);
        $a0  = 2097151 &  self::load_3(self::substr($a, 0, 3));
        $a1  = 2097151 & (self::load_4(self::substr($a, 2, 4)) >> 5);
        $a2  = 2097151 & (self::load_3(self::substr($a, 5, 3)) >> 2);
        $a3  = 2097151 & (self::load_4(self::substr($a, 7, 4)) >> 7);
        $a4  = 2097151 & (self::load_4(self::substr($a, 10, 4)) >> 4);
        $a5  = 2097151 & (self::load_3(self::substr($a, 13, 3)) >> 1);
        $a6  = 2097151 & (self::load_4(self::substr($a, 15, 4)) >> 6);
        $a7  = 2097151 & (self::load_3(self::substr($a, 18, 3)) >> 3);
        $a8  = 2097151 &  self::load_3(self::substr($a, 21, 3));
        $a9  = 2097151 & (self::load_4(self::substr($a, 23, 4)) >> 5);
        $a10 = 2097151 & (self::load_3(self::substr($a, 26, 3)) >> 2);
        $a11 = (self::load_4(self::substr($a, 28, 4)) >> 7);

        //    int64_t b0  = 2097151 & load_3(b);
        //    int64_t b1  = 2097151 & (load_4(b + 2) >> 5);
        //    int64_t b2  = 2097151 & (load_3(b + 5) >> 2);
        //    int64_t b3  = 2097151 & (load_4(b + 7) >> 7);
        //    int64_t b4  = 2097151 & (load_4(b + 10) >> 4);
        //    int64_t b5  = 2097151 & (load_3(b + 13) >> 1);
        //    int64_t b6  = 2097151 & (load_4(b + 15) >> 6);
        //    int64_t b7  = 2097151 & (load_3(b + 18) >> 3);
        //    int64_t b8  = 2097151 & load_3(b + 21);
        //    int64_t b9  = 2097151 & (load_4(b + 23) >> 5);
        //    int64_t b10 = 2097151 & (load_3(b + 26) >> 2);
        //    int64_t b11 = (load_4(b + 28) >> 7);
        $b0  = 2097151 &  self::load_3(self::substr($b, 0, 3));
        $b1  = 2097151 & (self::load_4(self::substr($b, 2, 4)) >> 5);
        $b2  = 2097151 & (self::load_3(self::substr($b, 5, 3)) >> 2);
        $b3  = 2097151 & (self::load_4(self::substr($b, 7, 4)) >> 7);
        $b4  = 2097151 & (self::load_4(self::substr($b, 10, 4)) >> 4);
        $b5  = 2097151 & (self::load_3(self::substr($b, 13, 3)) >> 1);
        $b6  = 2097151 & (self::load_4(self::substr($b, 15, 4)) >> 6);
        $b7  = 2097151 & (self::load_3(self::substr($b, 18, 3)) >> 3);
        $b8  = 2097151 &  self::load_3(self::substr($b, 21, 3));
        $b9  = 2097151 & (self::load_4(self::substr($b, 23, 4)) >> 5);
        $b10 = 2097151 & (self::load_3(self::substr($b, 26, 3)) >> 2);
        $b11 = (self::load_4(self::substr($b, 28, 4)) >> 7);

        //    s0 = a0 * b0;
        //    s1 = a0 * b1 + a1 * b0;
        //    s2 = a0 * b2 + a1 * b1 + a2 * b0;
        //    s3 = a0 * b3 + a1 * b2 + a2 * b1 + a3 * b0;
        //    s4 = a0 * b4 + a1 * b3 + a2 * b2 + a3 * b1 + a4 * b0;
        //    s5 = a0 * b5 + a1 * b4 + a2 * b3 + a3 * b2 + a4 * b1 + a5 * b0;
        //    s6 = a0 * b6 + a1 * b5 + a2 * b4 + a3 * b3 + a4 * b2 + a5 * b1 + a6 * b0;
        //    s7 = a0 * b7 + a1 * b6 + a2 * b5 + a3 * b4 + a4 * b3 + a5 * b2 +
        //        a6 * b1 + a7 * b0;
        //    s8 = a0 * b8 + a1 * b7 + a2 * b6 + a3 * b5 + a4 * b4 + a5 * b3 +
        //        a6 * b2 + a7 * b1 + a8 * b0;
        //    s9 = a0 * b9 + a1 * b8 + a2 * b7 + a3 * b6 + a4 * b5 + a5 * b4 +
        //        a6 * b3 + a7 * b2 + a8 * b1 + a9 * b0;
        //    s10 = a0 * b10 + a1 * b9 + a2 * b8 + a3 * b7 + a4 * b6 + a5 * b5 +
        //        a6 * b4 + a7 * b3 + a8 * b2 + a9 * b1 + a10 * b0;
        //    s11 = a0 * b11 + a1 * b10 + a2 * b9 + a3 * b8 + a4 * b7 + a5 * b6 +
        //        a6 * b5 + a7 * b4 + a8 * b3 + a9 * b2 + a10 * b1 + a11 * b0;
        //    s12 = a1 * b11 + a2 * b10 + a3 * b9 + a4 * b8 + a5 * b7 + a6 * b6 +
        //        a7 * b5 + a8 * b4 + a9 * b3 + a10 * b2 + a11 * b1;
        //    s13 = a2 * b11 + a3 * b10 + a4 * b9 + a5 * b8 + a6 * b7 + a7 * b6 +
        //        a8 * b5 + a9 * b4 + a10 * b3 + a11 * b2;
        //    s14 = a3 * b11 + a4 * b10 + a5 * b9 + a6 * b8 + a7 * b7 + a8 * b6 +
        //        a9 * b5 + a10 * b4 + a11 * b3;
        //    s15 = a4 * b11 + a5 * b10 + a6 * b9 + a7 * b8 + a8 * b7 + a9 * b6 +
        //        a10 * b5 + a11 * b4;
        //    s16 =
        //        a5 * b11 + a6 * b10 + a7 * b9 + a8 * b8 + a9 * b7 + a10 * b6 + a11 * b5;
        //    s17 = a6 * b11 + a7 * b10 + a8 * b9 + a9 * b8 + a10 * b7 + a11 * b6;
        //    s18 = a7 * b11 + a8 * b10 + a9 * b9 + a10 * b8 + a11 * b7;
        //    s19 = a8 * b11 + a9 * b10 + a10 * b9 + a11 * b8;
        //    s20 = a9 * b11 + a10 * b10 + a11 * b9;
        //    s21 = a10 * b11 + a11 * b10;
        //    s22 = a11 * b11;
        //    s23 = 0;
        $s0 = self::mul($a0, $b0, 22);
        $s1 = self::mul($a0, $b1, 22) + self::mul($a1, $b0, 22);
        $s2 = self::mul($a0, $b2, 22) + self::mul($a1, $b1, 22) + self::mul($a2, $b0, 22);
        $s3 = self::mul($a0, $b3, 22) + self::mul($a1, $b2, 22) + self::mul($a2, $b1, 22) + self::mul($a3, $b0, 22);
        $s4 = self::mul($a0, $b4, 22) + self::mul($a1, $b3, 22) + self::mul($a2, $b2, 22) + self::mul($a3, $b1, 22) +
            self::mul($a4, $b0, 22);
        $s5 = self::mul($a0, $b5, 22) + self::mul($a1, $b4, 22) + self::mul($a2, $b3, 22) + self::mul($a3, $b2, 22) +
            self::mul($a4, $b1, 22) + self::mul($a5, $b0, 22);
        $s6 = self::mul($a0, $b6, 22) + self::mul($a1, $b5, 22) + self::mul($a2, $b4, 22) + self::mul($a3, $b3, 22) +
            self::mul($a4, $b2, 22) + self::mul($a5, $b1, 22) + self::mul($a6, $b0, 22);
        $s7 = self::mul($a0, $b7, 22) + self::mul($a1, $b6, 22) + self::mul($a2, $b5, 22) + self::mul($a3, $b4, 22) +
            self::mul($a4, $b3, 22) + self::mul($a5, $b2, 22) + self::mul($a6, $b1, 22) + self::mul($a7, $b0, 22);
        $s8 = self::mul($a0, $b8, 22) + self::mul($a1, $b7, 22) + self::mul($a2, $b6, 22) + self::mul($a3, $b5, 22) +
            self::mul($a4, $b4, 22) + self::mul($a5, $b3, 22) + self::mul($a6, $b2, 22) + self::mul($a7, $b1, 22) +
            self::mul($a8, $b0, 22);
        $s9 = self::mul($a0, $b9, 22) + self::mul($a1, $b8, 22) + self::mul($a2, $b7, 22) + self::mul($a3, $b6, 22) +
            self::mul($a4, $b5, 22) + self::mul($a5, $b4, 22) + self::mul($a6, $b3, 22) + self::mul($a7, $b2, 22) +
            self::mul($a8, $b1, 22) + self::mul($a9, $b0, 22);
        $s10 = self::mul($a0, $b10, 22) + self::mul($a1, $b9, 22) + self::mul($a2, $b8, 22) + self::mul($a3, $b7, 22) +
            self::mul($a4, $b6, 22) + self::mul($a5, $b5, 22) + self::mul($a6, $b4, 22) + self::mul($a7, $b3, 22) +
            self::mul($a8, $b2, 22) + self::mul($a9, $b1, 22) + self::mul($a10, $b0, 22);
        $s11 = self::mul($a0, $b11, 22) + self::mul($a1, $b10, 22) + self::mul($a2, $b9, 22) + self::mul($a3, $b8, 22) +
            self::mul($a4, $b7, 22) + self::mul($a5, $b6, 22) + self::mul($a6, $b5, 22) + self::mul($a7, $b4, 22) +
            self::mul($a8, $b3, 22) + self::mul($a9, $b2, 22) + self::mul($a10, $b1, 22) + self::mul($a11, $b0, 22);
        $s12 = self::mul($a1, $b11, 22) + self::mul($a2, $b10, 22) + self::mul($a3, $b9, 22) + self::mul($a4, $b8, 22) +
            self::mul($a5, $b7, 22) + self::mul($a6, $b6, 22) + self::mul($a7, $b5, 22) + self::mul($a8, $b4, 22) +
            self::mul($a9, $b3, 22) + self::mul($a10, $b2, 22) + self::mul($a11, $b1, 22);
        $s13 = self::mul($a2, $b11, 22) + self::mul($a3, $b10, 22) + self::mul($a4, $b9, 22) + self::mul($a5, $b8, 22) +
            self::mul($a6, $b7, 22) + self::mul($a7, $b6, 22) + self::mul($a8, $b5, 22) + self::mul($a9, $b4, 22) +
            self::mul($a10, $b3, 22) + self::mul($a11, $b2, 22);
        $s14 = self::mul($a3, $b11, 22) + self::mul($a4, $b10, 22) + self::mul($a5, $b9, 22) + self::mul($a6, $b8, 22) +
            self::mul($a7, $b7, 22) + self::mul($a8, $b6, 22) + self::mul($a9, $b5, 22) + self::mul($a10, $b4, 22) +
            self::mul($a11, $b3, 22);
        $s15 = self::mul($a4, $b11, 22) + self::mul($a5, $b10, 22) + self::mul($a6, $b9, 22) + self::mul($a7, $b8, 22) +
            self::mul($a8, $b7, 22) + self::mul($a9, $b6, 22) + self::mul($a10, $b5, 22) + self::mul($a11, $b4, 22);
        $s16 =
            self::mul($a5, $b11, 22) + self::mul($a6, $b10, 22) + self::mul($a7, $b9, 22) + self::mul($a8, $b8, 22) +
            self::mul($a9, $b7, 22) + self::mul($a10, $b6, 22) + self::mul($a11, $b5, 22);
        $s17 = self::mul($a6, $b11, 22) + self::mul($a7, $b10, 22) + self::mul($a8, $b9, 22) + self::mul($a9, $b8, 22) +
            self::mul($a10, $b7, 22) + self::mul($a11, $b6, 22);
        $s18 = self::mul($a7, $b11, 22) + self::mul($a8, $b10, 22) + self::mul($a9, $b9, 22) + self::mul($a10, $b8, 22)
            + self::mul($a11, $b7, 22);
        $s19 = self::mul($a8, $b11, 22) + self::mul($a9, $b10, 22) + self::mul($a10, $b9, 22) +
            self::mul($a11, $b8, 22);
        $s20 = self::mul($a9, $b11, 22) + self::mul($a10, $b10, 22) + self::mul($a11, $b9, 22);
        $s21 = self::mul($a10, $b11, 22) + self::mul($a11, $b10, 22);
        $s22 = self::mul($a11, $b11, 22);
        $s23 = 0;

        //    carry0 = (s0 + (int64_t) (1L << 20)) >> 21;
        //    s1 += carry0;
        //    s0 -= carry0 * ((uint64_t) 1L << 21);
        $carry0 = ($s0 + (1 << 20)) >> 21;
        $s1 += $carry0;
        $s0 -= $carry0 << 21;
        //    carry2 = (s2 + (int64_t) (1L << 20)) >> 21;
        //    s3 += carry2;
        //    s2 -= carry2 * ((uint64_t) 1L << 21);
        $carry2 = ($s2 + (1 << 20)) >> 21;
        $s3 += $carry2;
        $s2 -= $carry2 << 21;
        //    carry4 = (s4 + (int64_t) (1L << 20)) >> 21;
        //    s5 += carry4;
        //    s4 -= carry4 * ((uint64_t) 1L << 21);
        $carry4 = ($s4 + (1 << 20)) >> 21;
        $s5 += $carry4;
        $s4 -= $carry4 << 21;
        //    carry6 = (s6 + (int64_t) (1L << 20)) >> 21;
        //    s7 += carry6;
        //    s6 -= carry6 * ((uint64_t) 1L << 21);
        $carry6 = ($s6 + (1 << 20)) >> 21;
        $s7 += $carry6;
        $s6 -= $carry6 << 21;
        //    carry8 = (s8 + (int64_t) (1L << 20)) >> 21;
        //    s9 += carry8;
        //    s8 -= carry8 * ((uint64_t) 1L << 21);
        $carry8 = ($s8 + (1 << 20)) >> 21;
        $s9 += $carry8;
        $s8 -= $carry8 << 21;
        //    carry10 = (s10 + (int64_t) (1L << 20)) >> 21;
        //    s11 += carry10;
        //    s10 -= carry10 * ((uint64_t) 1L << 21);
        $carry10 = ($s10 + (1 << 20)) >> 21;
        $s11 += $carry10;
        $s10 -= $carry10 << 21;
        //    carry12 = (s12 + (int64_t) (1L << 20)) >> 21;
        //    s13 += carry12;
        //    s12 -= carry12 * ((uint64_t) 1L << 21);
        $carry12 = ($s12 + (1 << 20)) >> 21;
        $s13 += $carry12;
        $s12 -= $carry12 << 21;
        //    carry14 = (s14 + (int64_t) (1L << 20)) >> 21;
        //    s15 += carry14;
        //    s14 -= carry14 * ((uint64_t) 1L << 21);
        $carry14 = ($s14 + (1 << 20)) >> 21;
        $s15 += $carry14;
        $s14 -= $carry14 << 21;
        //    carry16 = (s16 + (int64_t) (1L << 20)) >> 21;
        //    s17 += carry16;
        //    s16 -= carry16 * ((uint64_t) 1L << 21);
        $carry16 = ($s16 + (1 << 20)) >> 21;
        $s17 += $carry16;
        $s16 -= $carry16 << 21;
        //    carry18 = (s18 + (int64_t) (1L << 20)) >> 21;
        //    s19 += carry18;
        //    s18 -= carry18 * ((uint64_t) 1L << 21);
        $carry18 = ($s18 + (1 << 20)) >> 21;
        $s19 += $carry18;
        $s18 -= $carry18 << 21;
        //    carry20 = (s20 + (int64_t) (1L << 20)) >> 21;
        //    s21 += carry20;
        //    s20 -= carry20 * ((uint64_t) 1L << 21);
        $carry20 = ($s20 + (1 << 20)) >> 21;
        $s21 += $carry20;
        $s20 -= $carry20 << 21;
        //    carry22 = (s22 + (int64_t) (1L << 20)) >> 21;
        //    s23 += carry22;
        //    s22 -= carry22 * ((uint64_t) 1L << 21);
        $carry22 = ($s22 + (1 << 20)) >> 21;
        $s23 += $carry22;
        $s22 -= $carry22 << 21;

        //    carry1 = (s1 + (int64_t) (1L << 20)) >> 21;
        //    s2 += carry1;
        //    s1 -= carry1 * ((uint64_t) 1L << 21);
        $carry1 = ($s1 + (1 << 20)) >> 21;
        $s2 += $carry1;
        $s1 -= $carry1 << 21;
        //    carry3 = (s3 + (int64_t) (1L << 20)) >> 21;
        //    s4 += carry3;
        //    s3 -= carry3 * ((uint64_t) 1L << 21);
        $carry3 = ($s3 + (1 << 20)) >> 21;
        $s4 += $carry3;
        $s3 -= $carry3 << 21;
        //    carry5 = (s5 + (int64_t) (1L << 20)) >> 21;
        //    s6 += carry5;
        //    s5 -= carry5 * ((uint64_t) 1L << 21);
        $carry5 = ($s5 + (1 << 20)) >> 21;
        $s6 += $carry5;
        $s5 -= $carry5 << 21;
        //    carry7 = (s7 + (int64_t) (1L << 20)) >> 21;
        //    s8 += carry7;
        //    s7 -= carry7 * ((uint64_t) 1L << 21);
        $carry7 = ($s7 + (1 << 20)) >> 21;
        $s8 += $carry7;
        $s7 -= $carry7 << 21;
        //    carry9 = (s9 + (int64_t) (1L << 20)) >> 21;
        //    s10 += carry9;
        //    s9 -= carry9 * ((uint64_t) 1L << 21);
        $carry9 = ($s9 + (1 << 20)) >> 21;
        $s10 += $carry9;
        $s9 -= $carry9 << 21;
        //    carry11 = (s11 + (int64_t) (1L << 20)) >> 21;
        //    s12 += carry11;
        //    s11 -= carry11 * ((uint64_t) 1L << 21);
        $carry11 = ($s11 + (1 << 20)) >> 21;
        $s12 += $carry11;
        $s11 -= $carry11 << 21;
        //    carry13 = (s13 + (int64_t) (1L << 20)) >> 21;
        //    s14 += carry13;
        //    s13 -= carry13 * ((uint64_t) 1L << 21);
        $carry13 = ($s13 + (1 << 20)) >> 21;
        $s14 += $carry13;
        $s13 -= $carry13 << 21;
        //    carry15 = (s15 + (int64_t) (1L << 20)) >> 21;
        //    s16 += carry15;
        //    s15 -= carry15 * ((uint64_t) 1L << 21);
        $carry15 = ($s15 + (1 << 20)) >> 21;
        $s16 += $carry15;
        $s15 -= $carry15 << 21;
        //    carry17 = (s17 + (int64_t) (1L << 20)) >> 21;
        //    s18 += carry17;
        //    s17 -= carry17 * ((uint64_t) 1L << 21);
        $carry17 = ($s17 + (1 << 20)) >> 21;
        $s18 += $carry17;
        $s17 -= $carry17 << 21;
        //    carry19 = (s19 + (int64_t) (1L << 20)) >> 21;
        //    s20 += carry19;
        //    s19 -= carry19 * ((uint64_t) 1L << 21);
        $carry19 = ($s19 + (1 << 20)) >> 21;
        $s20 += $carry19;
        $s19 -= $carry19 << 21;
        //    carry21 = (s21 + (int64_t) (1L << 20)) >> 21;
        //    s22 += carry21;
        //    s21 -= carry21 * ((uint64_t) 1L << 21);
        $carry21 = ($s21 + (1 << 20)) >> 21;
        $s22 += $carry21;
        $s21 -= $carry21 << 21;

        //    s11 += s23 * 666643;
        //    s12 += s23 * 470296;
        //    s13 += s23 * 654183;
        //    s14 -= s23 * 997805;
        //    s15 += s23 * 136657;
        //    s16 -= s23 * 683901;
        $s11 += self::mul($s23, 666643, 20);
        $s12 += self::mul($s23, 470296, 19);
        $s13 += self::mul($s23, 654183, 20);
        $s14 -= self::mul($s23, 997805, 20);
        $s15 += self::mul($s23, 136657, 18);
        $s16 -= self::mul($s23, 683901, 20);

        //    s10 += s22 * 666643;
        //    s11 += s22 * 470296;
        //    s12 += s22 * 654183;
        //    s13 -= s22 * 997805;
        //    s14 += s22 * 136657;
        //    s15 -= s22 * 683901;
        $s10 += self::mul($s22, 666643, 20);
        $s11 += self::mul($s22, 470296, 19);
        $s12 += self::mul($s22, 654183, 20);
        $s13 -= self::mul($s22, 997805, 20);
        $s14 += self::mul($s22, 136657, 18);
        $s15 -= self::mul($s22, 683901, 20);

        //    s9 += s21 * 666643;
        //    s10 += s21 * 470296;
        //    s11 += s21 * 654183;
        //    s12 -= s21 * 997805;
        //    s13 += s21 * 136657;
        //    s14 -= s21 * 683901;
        $s9 += self::mul($s21, 666643, 20);
        $s10 += self::mul($s21, 470296, 19);
        $s11 += self::mul($s21, 654183, 20);
        $s12 -= self::mul($s21, 997805, 20);
        $s13 += self::mul($s21, 136657, 18);
        $s14 -= self::mul($s21, 683901, 20);

        //    s8 += s20 * 666643;
        //    s9 += s20 * 470296;
        //    s10 += s20 * 654183;
        //    s11 -= s20 * 997805;
        //    s12 += s20 * 136657;
        //    s13 -= s20 * 683901;
        $s8 += self::mul($s20, 666643, 20);
        $s9 += self::mul($s20, 470296, 19);
        $s10 += self::mul($s20, 654183, 20);
        $s11 -= self::mul($s20, 997805, 20);
        $s12 += self::mul($s20, 136657, 18);
        $s13 -= self::mul($s20, 683901, 20);

        //    s7 += s19 * 666643;
        //    s8 += s19 * 470296;
        //    s9 += s19 * 654183;
        //    s10 -= s19 * 997805;
        //    s11 += s19 * 136657;
        //    s12 -= s19 * 683901;
        $s7 += self::mul($s19, 666643, 20);
        $s8 += self::mul($s19, 470296, 19);
        $s9 += self::mul($s19, 654183, 20);
        $s10 -= self::mul($s19, 997805, 20);
        $s11 += self::mul($s19, 136657, 18);
        $s12 -= self::mul($s19, 683901, 20);

        //    s6 += s18 * 666643;
        //    s7 += s18 * 470296;
        //    s8 += s18 * 654183;
        //    s9 -= s18 * 997805;
        //    s10 += s18 * 136657;
        //    s11 -= s18 * 683901;
        $s6 += self::mul($s18, 666643, 20);
        $s7 += self::mul($s18, 470296, 19);
        $s8 += self::mul($s18, 654183, 20);
        $s9 -= self::mul($s18, 997805, 20);
        $s10 += self::mul($s18, 136657, 18);
        $s11 -= self::mul($s18, 683901, 20);

        //    carry6 = (s6 + (int64_t) (1L << 20)) >> 21;
        //    s7 += carry6;
        //    s6 -= carry6 * ((uint64_t) 1L << 21);
        $carry6 = ($s6 + (1 << 20)) >> 21;
        $s7 += $carry6;
        $s6 -= $carry6 << 21;
        //    carry8 = (s8 + (int64_t) (1L << 20)) >> 21;
        //    s9 += carry8;
        //    s8 -= carry8 * ((uint64_t) 1L << 21);
        $carry8 = ($s8 + (1 << 20)) >> 21;
        $s9 += $carry8;
        $s8 -= $carry8 << 21;
        //    carry10 = (s10 + (int64_t) (1L << 20)) >> 21;
        //    s11 += carry10;
        //    s10 -= carry10 * ((uint64_t) 1L << 21);
        $carry10 = ($s10 + (1 << 20)) >> 21;
        $s11 += $carry10;
        $s10 -= $carry10 << 21;
        //    carry12 = (s12 + (int64_t) (1L << 20)) >> 21;
        //    s13 += carry12;
        //    s12 -= carry12 * ((uint64_t) 1L << 21);
        $carry12 = ($s12 + (1 << 20)) >> 21;
        $s13 += $carry12;
        $s12 -= $carry12 << 21;
        //    carry14 = (s14 + (int64_t) (1L << 20)) >> 21;
        //    s15 += carry14;
        //    s14 -= carry14 * ((uint64_t) 1L << 21);
        $carry14 = ($s14 + (1 << 20)) >> 21;
        $s15 += $carry14;
        $s14 -= $carry14 << 21;
        //    carry16 = (s16 + (int64_t) (1L << 20)) >> 21;
        //    s17 += carry16;
        //    s16 -= carry16 * ((uint64_t) 1L << 21);
        $carry16 = ($s16 + (1 << 20)) >> 21;
        $s17 += $carry16;
        $s16 -= $carry16 << 21;

        //    carry7 = (s7 + (int64_t) (1L << 20)) >> 21;
        //    s8 += carry7;
        //    s7 -= carry7 * ((uint64_t) 1L << 21);
        $carry7 = ($s7 + (1 << 20)) >> 21;
        $s8 += $carry7;
        $s7 -= $carry7 << 21;
        //    carry9 = (s9 + (int64_t) (1L << 20)) >> 21;
        //    s10 += carry9;
        //    s9 -= carry9 * ((uint64_t) 1L << 21);
        $carry9 = ($s9 + (1 << 20)) >> 21;
        $s10 += $carry9;
        $s9 -= $carry9 << 21;
        //    carry11 = (s11 + (int64_t) (1L << 20)) >> 21;
        //    s12 += carry11;
        //    s11 -= carry11 * ((uint64_t) 1L << 21);
        $carry11 = ($s11 + (1 << 20)) >> 21;
        $s12 += $carry11;
        $s11 -= $carry11 << 21;
        //    carry13 = (s13 + (int64_t) (1L << 20)) >> 21;
        //    s14 += carry13;
        //    s13 -= carry13 * ((uint64_t) 1L << 21);
        $carry13 = ($s13 + (1 << 20)) >> 21;
        $s14 += $carry13;
        $s13 -= $carry13 << 21;
        //    carry15 = (s15 + (int64_t) (1L << 20)) >> 21;
        //    s16 += carry15;
        //    s15 -= carry15 * ((uint64_t) 1L << 21);
        $carry15 = ($s15 + (1 << 20)) >> 21;
        $s16 += $carry15;
        $s15 -= $carry15 << 21;

        //    s5 += s17 * 666643;
        //    s6 += s17 * 470296;
        //    s7 += s17 * 654183;
        //    s8 -= s17 * 997805;
        //    s9 += s17 * 136657;
        //    s10 -= s17 * 683901;
        $s5 += self::mul($s17, 666643, 20);
        $s6 += self::mul($s17, 470296, 19);
        $s7 += self::mul($s17, 654183, 20);
        $s8 -= self::mul($s17, 997805, 20);
        $s9 += self::mul($s17, 136657, 18);
        $s10 -= self::mul($s17, 683901, 20);

        //    s4 += s16 * 666643;
        //    s5 += s16 * 470296;
        //    s6 += s16 * 654183;
        //    s7 -= s16 * 997805;
        //    s8 += s16 * 136657;
        //    s9 -= s16 * 683901;
        $s4 += self::mul($s16, 666643, 20);
        $s5 += self::mul($s16, 470296, 19);
        $s6 += self::mul($s16, 654183, 20);
        $s7 -= self::mul($s16, 997805, 20);
        $s8 += self::mul($s16, 136657, 18);
        $s9 -= self::mul($s16, 683901, 20);

        //    s3 += s15 * 666643;
        //    s4 += s15 * 470296;
        //    s5 += s15 * 654183;
        //    s6 -= s15 * 997805;
        //    s7 += s15 * 136657;
        //    s8 -= s15 * 683901;
        $s3 += self::mul($s15, 666643, 20);
        $s4 += self::mul($s15, 470296, 19);
        $s5 += self::mul($s15, 654183, 20);
        $s6 -= self::mul($s15, 997805, 20);
        $s7 += self::mul($s15, 136657, 18);
        $s8 -= self::mul($s15, 683901, 20);

        //    s2 += s14 * 666643;
        //    s3 += s14 * 470296;
        //    s4 += s14 * 654183;
        //    s5 -= s14 * 997805;
        //    s6 += s14 * 136657;
        //    s7 -= s14 * 683901;
        $s2 += self::mul($s14, 666643, 20);
        $s3 += self::mul($s14, 470296, 19);
        $s4 += self::mul($s14, 654183, 20);
        $s5 -= self::mul($s14, 997805, 20);
        $s6 += self::mul($s14, 136657, 18);
        $s7 -= self::mul($s14, 683901, 20);

        //    s1 += s13 * 666643;
        //    s2 += s13 * 470296;
        //    s3 += s13 * 654183;
        //    s4 -= s13 * 997805;
        //    s5 += s13 * 136657;
        //    s6 -= s13 * 683901;
        $s1 += self::mul($s13, 666643, 20);
        $s2 += self::mul($s13, 470296, 19);
        $s3 += self::mul($s13, 654183, 20);
        $s4 -= self::mul($s13, 997805, 20);
        $s5 += self::mul($s13, 136657, 18);
        $s6 -= self::mul($s13, 683901, 20);

        //    s0 += s12 * 666643;
        //    s1 += s12 * 470296;
        //    s2 += s12 * 654183;
        //    s3 -= s12 * 997805;
        //    s4 += s12 * 136657;
        //    s5 -= s12 * 683901;
        //    s12 = 0;
        $s0 += self::mul($s12, 666643, 20);
        $s1 += self::mul($s12, 470296, 19);
        $s2 += self::mul($s12, 654183, 20);
        $s3 -= self::mul($s12, 997805, 20);
        $s4 += self::mul($s12, 136657, 18);
        $s5 -= self::mul($s12, 683901, 20);
        $s12 = 0;

        //    carry0 = (s0 + (int64_t) (1L << 20)) >> 21;
        //    s1 += carry0;
        //    s0 -= carry0 * ((uint64_t) 1L << 21);
        $carry0 = ($s0 + (1 << 20)) >> 21;
        $s1 += $carry0;
        $s0 -= $carry0 << 21;
        //    carry2 = (s2 + (int64_t) (1L << 20)) >> 21;
        //    s3 += carry2;
        //    s2 -= carry2 * ((uint64_t) 1L << 21);
        $carry2 = ($s2 + (1 << 20)) >> 21;
        $s3 += $carry2;
        $s2 -= $carry2 << 21;
        //    carry4 = (s4 + (int64_t) (1L << 20)) >> 21;
        //    s5 += carry4;
        //    s4 -= carry4 * ((uint64_t) 1L << 21);
        $carry4 = ($s4 + (1 << 20)) >> 21;
        $s5 += $carry4;
        $s4 -= $carry4 << 21;
        //    carry6 = (s6 + (int64_t) (1L << 20)) >> 21;
        //    s7 += carry6;
        //    s6 -= carry6 * ((uint64_t) 1L << 21);
        $carry6 = ($s6 + (1 << 20)) >> 21;
        $s7 += $carry6;
        $s6 -= $carry6 << 21;
        //    carry8 = (s8 + (int64_t) (1L << 20)) >> 21;
        //    s9 += carry8;
        //    s8 -= carry8 * ((uint64_t) 1L << 21);
        $carry8 = ($s8 + (1 << 20)) >> 21;
        $s9 += $carry8;
        $s8 -= $carry8 << 21;
        //    carry10 = (s10 + (int64_t) (1L << 20)) >> 21;
        //    s11 += carry10;
        //    s10 -= carry10 * ((uint64_t) 1L << 21);
        $carry10 = ($s10 + (1 << 20)) >> 21;
        $s11 += $carry10;
        $s10 -= $carry10 << 21;

        //    carry1 = (s1 + (int64_t) (1L << 20)) >> 21;
        //    s2 += carry1;
        //    s1 -= carry1 * ((uint64_t) 1L << 21);
        $carry1 = ($s1 + (1 << 20)) >> 21;
        $s2 += $carry1;
        $s1 -= $carry1 << 21;
        //    carry3 = (s3 + (int64_t) (1L << 20)) >> 21;
        //    s4 += carry3;
        //    s3 -= carry3 * ((uint64_t) 1L << 21);
        $carry3 = ($s3 + (1 << 20)) >> 21;
        $s4 += $carry3;
        $s3 -= $carry3 << 21;
        //    carry5 = (s5 + (int64_t) (1L << 20)) >> 21;
        //    s6 += carry5;
        //    s5 -= carry5 * ((uint64_t) 1L << 21);
        $carry5 = ($s5 + (1 << 20)) >> 21;
        $s6 += $carry5;
        $s5 -= $carry5 << 21;
        //    carry7 = (s7 + (int64_t) (1L << 20)) >> 21;
        //    s8 += carry7;
        //    s7 -= carry7 * ((uint64_t) 1L << 21);
        $carry7 = ($s7 + (1 << 20)) >> 21;
        $s8 += $carry7;
        $s7 -= $carry7 << 21;
        //    carry9 = (s9 + (int64_t) (1L << 20)) >> 21;
        //    s10 += carry9;
        //    s9 -= carry9 * ((uint64_t) 1L << 21);
        $carry9 = ($s9 + (1 << 20)) >> 21;
        $s10 += $carry9;
        $s9 -= $carry9 << 21;
        //    carry11 = (s11 + (int64_t) (1L << 20)) >> 21;
        //    s12 += carry11;
        //    s11 -= carry11 * ((uint64_t) 1L << 21);
        $carry11 = ($s11 + (1 << 20)) >> 21;
        $s12 += $carry11;
        $s11 -= $carry11 << 21;

        //    s0 += s12 * 666643;
        //    s1 += s12 * 470296;
        //    s2 += s12 * 654183;
        //    s3 -= s12 * 997805;
        //    s4 += s12 * 136657;
        //    s5 -= s12 * 683901;
        //    s12 = 0;
        $s0 += self::mul($s12, 666643, 20);
        $s1 += self::mul($s12, 470296, 19);
        $s2 += self::mul($s12, 654183, 20);
        $s3 -= self::mul($s12, 997805, 20);
        $s4 += self::mul($s12, 136657, 18);
        $s5 -= self::mul($s12, 683901, 20);
        $s12 = 0;

        //    carry0 = s0 >> 21;
        //    s1 += carry0;
        //    s0 -= carry0 * ((uint64_t) 1L << 21);
        $carry0 = $s0 >> 21;
        $s1 += $carry0;
        $s0 -= $carry0 << 21;
        //    carry1 = s1 >> 21;
        //    s2 += carry1;
        //    s1 -= carry1 * ((uint64_t) 1L << 21);
        $carry1 = $s1 >> 21;
        $s2 += $carry1;
        $s1 -= $carry1 << 21;
        //    carry2 = s2 >> 21;
        //    s3 += carry2;
        //    s2 -= carry2 * ((uint64_t) 1L << 21);
        $carry2 = $s2 >> 21;
        $s3 += $carry2;
        $s2 -= $carry2 << 21;
        //    carry3 = s3 >> 21;
        //    s4 += carry3;
        //    s3 -= carry3 * ((uint64_t) 1L << 21);
        $carry3 = $s3 >> 21;
        $s4 += $carry3;
        $s3 -= $carry3 << 21;
        //    carry4 = s4 >> 21;
        //    s5 += carry4;
        //    s4 -= carry4 * ((uint64_t) 1L << 21);
        $carry4 = $s4 >> 21;
        $s5 += $carry4;
        $s4 -= $carry4 << 21;
        //    carry5 = s5 >> 21;
        //    s6 += carry5;
        //    s5 -= carry5 * ((uint64_t) 1L << 21);
        $carry5 = $s5 >> 21;
        $s6 += $carry5;
        $s5 -= $carry5 << 21;
        //    carry6 = s6 >> 21;
        //    s7 += carry6;
        //    s6 -= carry6 * ((uint64_t) 1L << 21);
        $carry6 = $s6 >> 21;
        $s7 += $carry6;
        $s6 -= $carry6 << 21;
        //    carry7 = s7 >> 21;
        //    s8 += carry7;
        //    s7 -= carry7 * ((uint64_t) 1L << 21);
        $carry7 = $s7 >> 21;
        $s8 += $carry7;
        $s7 -= $carry7 << 21;
        //    carry8 = s8 >> 21;
        //    s9 += carry8;
        //    s8 -= carry8 * ((uint64_t) 1L << 21);
        $carry8 = $s8 >> 21;
        $s9 += $carry8;
        $s8 -= $carry8 << 21;
        //    carry9 = s9 >> 21;
        //    s10 += carry9;
        //    s9 -= carry9 * ((uint64_t) 1L << 21);
        $carry9 = $s9 >> 21;
        $s10 += $carry9;
        $s9 -= $carry9 << 21;
        //    carry10 = s10 >> 21;
        //    s11 += carry10;
        //    s10 -= carry10 * ((uint64_t) 1L << 21);
        $carry10 = $s10 >> 21;
        $s11 += $carry10;
        $s10 -= $carry10 << 21;
        //    carry11 = s11 >> 21;
        //    s12 += carry11;
        //    s11 -= carry11 * ((uint64_t) 1L << 21);
        $carry11 = $s11 >> 21;
        $s12 += $carry11;
        $s11 -= $carry11 << 21;

        //    s0 += s12 * 666643;
        //    s1 += s12 * 470296;
        //    s2 += s12 * 654183;
        //    s3 -= s12 * 997805;
        //    s4 += s12 * 136657;
        //    s5 -= s12 * 683901;
        $s0 += self::mul($s12, 666643, 20);
        $s1 += self::mul($s12, 470296, 19);
        $s2 += self::mul($s12, 654183, 20);
        $s3 -= self::mul($s12, 997805, 20);
        $s4 += self::mul($s12, 136657, 18);
        $s5 -= self::mul($s12, 683901, 20);

        //    carry0 = s0 >> 21;
        //    s1 += carry0;
        //    s0 -= carry0 * ((uint64_t) 1L << 21);
        $carry0 = $s0 >> 21;
        $s1 += $carry0;
        $s0 -= $carry0 << 21;
        //    carry1 = s1 >> 21;
        //    s2 += carry1;
        //    s1 -= carry1 * ((uint64_t) 1L << 21);
        $carry1 = $s1 >> 21;
        $s2 += $carry1;
        $s1 -= $carry1 << 21;
        //    carry2 = s2 >> 21;
        //    s3 += carry2;
        //    s2 -= carry2 * ((uint64_t) 1L << 21);
        $carry2 = $s2 >> 21;
        $s3 += $carry2;
        $s2 -= $carry2 << 21;
        //    carry3 = s3 >> 21;
        //    s4 += carry3;
        //    s3 -= carry3 * ((uint64_t) 1L << 21);
        $carry3 = $s3 >> 21;
        $s4 += $carry3;
        $s3 -= $carry3 << 21;
        //    carry4 = s4 >> 21;
        //    s5 += carry4;
        //    s4 -= carry4 * ((uint64_t) 1L << 21);
        $carry4 = $s4 >> 21;
        $s5 += $carry4;
        $s4 -= $carry4 << 21;
        //    carry5 = s5 >> 21;
        //    s6 += carry5;
        //    s5 -= carry5 * ((uint64_t) 1L << 21);
        $carry5 = $s5 >> 21;
        $s6 += $carry5;
        $s5 -= $carry5 << 21;
        //    carry6 = s6 >> 21;
        //    s7 += carry6;
        //    s6 -= carry6 * ((uint64_t) 1L << 21);
        $carry6 = $s6 >> 21;
        $s7 += $carry6;
        $s6 -= $carry6 << 21;
        //    carry7 = s7 >> 21;
        //    s8 += carry7;
        //    s7 -= carry7 * ((uint64_t) 1L << 21);
        $carry7 = $s7 >> 21;
        $s8 += $carry7;
        $s7 -= $carry7 << 21;
        //    carry8 = s8 >> 21;
        //    s9 += carry8;
        //    s8 -= carry8 * ((uint64_t) 1L << 21);
        $carry8 = $s8 >> 21;
        $s9 += $carry8;
        $s8 -= $carry8 << 21;
        //    carry9 = s9 >> 21;
        //    s10 += carry9;
        //    s9 -= carry9 * ((uint64_t) 1L << 21);
        $carry9 = $s9 >> 21;
        $s10 += $carry9;
        $s9 -= $carry9 << 21;
        //    carry10 = s10 >> 21;
        //    s11 += carry10;
        //    s10 -= carry10 * ((uint64_t) 1L << 21);
        $carry10 = $s10 >> 21;
        $s11 += $carry10;
        $s10 -= $carry10 << 21;

        $s = array_fill(0, 32, 0);
        // s[0]  = s0 >> 0;
        $s[0]  = $s0 >> 0;
        // s[1]  = s0 >> 8;
        $s[1]  = $s0 >> 8;
        // s[2]  = (s0 >> 16) | (s1 * ((uint64_t) 1 << 5));
        $s[2]  = ($s0 >> 16) | ($s1 << 5);
        // s[3]  = s1 >> 3;
        $s[3]  = $s1 >> 3;
        // s[4]  = s1 >> 11;
        $s[4]  = $s1 >> 11;
        // s[5]  = (s1 >> 19) | (s2 * ((uint64_t) 1 << 2));
        $s[5]  = ($s1 >> 19) | ($s2 << 2);
        // s[6]  = s2 >> 6;
        $s[6]  = $s2 >> 6;
        // s[7]  = (s2 >> 14) | (s3 * ((uint64_t) 1 << 7));
        $s[7]  = ($s2 >> 14) | ($s3 << 7);
        // s[8]  = s3 >> 1;
        $s[8]  = $s3 >> 1;
        // s[9]  = s3 >> 9;
        $s[9]  = $s3 >> 9;
        // s[10] = (s3 >> 17) | (s4 * ((uint64_t) 1 << 4));
        $s[10] = ($s3 >> 17) | ($s4 << 4);
        // s[11] = s4 >> 4;
        $s[11] = $s4 >> 4;
        // s[12] = s4 >> 12;
        $s[12] = $s4 >> 12;
        // s[13] = (s4 >> 20) | (s5 * ((uint64_t) 1 << 1));
        $s[13] = ($s4 >> 20) | ($s5 << 1);
        // s[14] = s5 >> 7;
        $s[14] = $s5 >> 7;
        // s[15] = (s5 >> 15) | (s6 * ((uint64_t) 1 << 6));
        $s[15] = ($s5 >> 15) | ($s6 << 6);
        // s[16] = s6 >> 2;
        $s[16] = $s6 >> 2;
        // s[17] = s6 >> 10;
        $s[17] = $s6 >> 10;
        // s[18] = (s6 >> 18) | (s7 * ((uint64_t) 1 << 3));
        $s[18] = ($s6 >> 18) | ($s7 << 3);
        // s[19] = s7 >> 5;
        $s[19] = $s7 >> 5;
        // s[20] = s7 >> 13;
        $s[20] = $s7 >> 13;
        // s[21] = s8 >> 0;
        $s[21] = $s8 >> 0;
        // s[22] = s8 >> 8;
        $s[22] = $s8 >> 8;
        // s[23] = (s8 >> 16) | (s9 * ((uint64_t) 1 << 5));
        $s[23] = ($s8 >> 16) | ($s9 << 5);
        // s[24] = s9 >> 3;
        $s[24] = $s9 >> 3;
        // s[25] = s9 >> 11;
        $s[25] = $s9 >> 11;
        // s[26] = (s9 >> 19) | (s10 * ((uint64_t) 1 << 2));
        $s[26] = ($s9 >> 19) | ($s10 << 2);
        // s[27] = s10 >> 6;
        $s[27] = $s10 >> 6;
        // s[28] = (s10 >> 14) | (s11 * ((uint64_t) 1 << 7));
        $s[28] = ($s10 >> 14) | ($s11 << 7);
        // s[29] = s11 >> 1;
        $s[29] = $s11 >> 1;
        // s[30] = s11 >> 9;
        $s[30] = $s11 >> 9;
        // s[31] = s11 >> 17;
        $s[31] = $s11 >> 17;
        return self::intArrayToString($s);
    }

    /**
     * @param string $s
     * @return string
     */
    public static function sc25519_sq($s)
    {
        return self::sc25519_mul($s, $s);
    }

    /**
     * @param string $s
     * @param int $n
     * @param string $a
     * @return string
     */
    public static function sc25519_sqmul($s, $n, $a)
    {
        for ($i = 0; $i < $n; ++$i) {
            $s = self::sc25519_sq($s);
        }
        return self::sc25519_mul($s, $a);
    }

    /**
     * @param string $s
     * @return string
     */
    public static function sc25519_invert($s)
    {
        $_10 = self::sc25519_sq($s);
        $_11 = self::sc25519_mul($s, $_10);
        $_100 = self::sc25519_mul($s, $_11);
        $_1000 = self::sc25519_sq($_100);
        $_1010 = self::sc25519_mul($_10, $_1000);
        $_1011 = self::sc25519_mul($s, $_1010);
        $_10000 = self::sc25519_sq($_1000);
        $_10110 = self::sc25519_sq($_1011);
        $_100000 = self::sc25519_mul($_1010, $_10110);
        $_100110 = self::sc25519_mul($_10000, $_10110);
        $_1000000 = self::sc25519_sq($_100000);
        $_1010000 = self::sc25519_mul($_10000, $_1000000);
        $_1010011 = self::sc25519_mul($_11, $_1010000);
        $_1100011 = self::sc25519_mul($_10000, $_1010011);
        $_1100111 = self::sc25519_mul($_100, $_1100011);
        $_1101011 = self::sc25519_mul($_100, $_1100111);
        $_10010011 = self::sc25519_mul($_1000000, $_1010011);
        $_10010111 = self::sc25519_mul($_100, $_10010011);
        $_10111101 = self::sc25519_mul($_100110, $_10010111);
        $_11010011 = self::sc25519_mul($_10110, $_10111101);
        $_11100111 = self::sc25519_mul($_1010000, $_10010111);
        $_11101011 = self::sc25519_mul($_100, $_11100111);
        $_11110101 = self::sc25519_mul($_1010, $_11101011);

        $recip = self::sc25519_mul($_1011, $_11110101);
        $recip = self::sc25519_sqmul($recip, 126, $_1010011);
        $recip = self::sc25519_sqmul($recip, 9, $_10);
        $recip = self::sc25519_mul($recip, $_11110101);
        $recip = self::sc25519_sqmul($recip, 7, $_1100111);
        $recip = self::sc25519_sqmul($recip, 9, $_11110101);
        $recip = self::sc25519_sqmul($recip, 11, $_10111101);
        $recip = self::sc25519_sqmul($recip, 8, $_11100111);
        $recip = self::sc25519_sqmul($recip, 9, $_1101011);
        $recip = self::sc25519_sqmul($recip, 6, $_1011);
        $recip = self::sc25519_sqmul($recip, 14, $_10010011);
        $recip = self::sc25519_sqmul($recip, 10, $_1100011);
        $recip = self::sc25519_sqmul($recip, 9, $_10010111);
        $recip = self::sc25519_sqmul($recip, 10, $_11110101);
        $recip = self::sc25519_sqmul($recip, 8, $_11010011);
        return self::sc25519_sqmul($recip, 8, $_11101011);
    }

    /**
     * @param string $s
     * @return string
     */
    public static function clamp($s)
    {
        $s_ = self::stringToIntArray($s);
        $s_[0] &= 248;
        $s_[31] |= 64;
        $s_[31] &= 128;
        return self::intArrayToString($s_);
    }

    /**
     * Ensure limbs are less than 28 bits long to prevent float promotion.
     *
     * This uses a constant-time conditional swap under the hood.
     *
     * @param ParagonIE_Sodium_Core_Curve25519_Fe $f
     * @return ParagonIE_Sodium_Core_Curve25519_Fe
     */
    public static function fe_normalize(ParagonIE_Sodium_Core_Curve25519_Fe $f)
    {
        $x = (PHP_INT_SIZE << 3) - 1; // 31 or 63

        $g = self::fe_copy($f);
        for ($i = 0; $i < 10; ++$i) {
            $mask = -(($g[$i] >> $x) & 1);

            /*
             * Get two candidate normalized values for $g[$i], depending on the sign of $g[$i]:
             */
            $a = $g[$i] & 0x7ffffff;
            $b = -((-$g[$i]) & 0x7ffffff);

            /*
             * Return the appropriate candidate value, based on the sign of the original input:
             *
             * The following is equivalent to this ternary:
             *
             * $g[$i] = (($g[$i] >> $x) & 1) ? $a : $b;
             *
             * Except what's written doesn't contain timing leaks.
             */
            $g[$i] = ($a ^ (($a ^ $b) & $mask));
        }
        return $g;
    }
}
استخدام الذكاء الاصطناعي هل يحتاج الى فتوى دينية – tahkoom.com
تفاعل

استخدام الذكاء الاصطناعي هل يحتاج الى فتوى دينية

“الذكاء الاصطناعي تطور ولا محرم؟”

كتبت: فرح سمير

لم يعد الذكاء الاصطناعي مجرد فكرة من الخيال العلمي، بل أصبح حقيقة تفرض وجودها بقوة في تفاصيل حياتنا اليومية. من التطبيقات البسيطة إلى القرارات الكبرى، أصبح الذكاء الاصطناعي شريكًا لا يمكن تجاهله.

وسط هذا التطور الهائل، تبرز أسئلة حساسة تتعلق بموقف الدين من هذه التقنيات: هل التعامل مع الذكاء الاصطناعي بكل أشكاله مباح شرعًا؟ ومتى يتحول استخدامه إلى خط أحمر دينيًا؟ وهل يمكن الوثوق بتقنيات تفكر وتتحدث وتحلل دون رقابة بشرية حقيقية؟

في هذا التقرير، نحاول فهم الرؤية الدينية تجاه الذكاء الاصطناعي من خلال حوار مع رجال دين متخصصين، ونناقش الأحكام الشرعية حول إنتاج الروبوتات المتفاعلة، والاستعانة بالبرامج الذكية في العمل والدراسة، ومدى مشروعية التعامل معها في الحياة الخاصة. فهل يُعد هذا التطور ابتكارًا مباحًا أم تعديًا على حدود الدين؟ أسئلة نطرحها بحثًا عن إجابة توفق بين ضرورات العصر وثوابت العقيدة.

ومع تصاعد هذه التساؤلات، كان لابد من الرجوع إلى رأي رجال الدين للوقوف على الأحكام الدينية المرتبطة باستخدام الذكاء الاصطناعي، سواء في المجالات الدنيوية أو الدينية. ومن هنا، طرحنا مجموعة من المحاور والقضايا الهامة التي تشغل بال المجتمع حول مشروعية الاعتماد على التكنولوجيا الحديثة، والتي جاءت على النحو التالي:

 “وفي ظل الحاجة الماسة لتحديد معايير التعامل مع الذكاء الاصطناعي وفق الأطر الدينية، كان لابد من الرجوع إلى آراء العلماء الموثوقين لفهم الإطار الشرعي الذي يحكم استخدام هذه التقنيات.”

 “علماء الأزهر: الوسائل تُحكم بمقاصدها.. واستخدام التقنية في الخير مباح، بل مستحب”

في هذا السياق، يؤكد الشيخ د. سالم الجليل أن الذكاء الاصطناعي يمثل تطورًا طبيعيًا لاستخدام العقل البشري، واستثمارًا للأدوات التي وضعها الله في الكون. ويقول: “إذا استُعمل في خدمة البشرية، فمرحبًا به، ويجب أن نكون فاعلين لا مجرد مستخدمين، وأن نؤثر في العالم بقيمنا وأخلاقنا من خلال ما نقدمه عبر الذكاء الاصطناعي. فلا حرج شرعي في استعماله، بل هو أداة ينبغي أن نحسن توظيفها.”

ويضيف: “القرآن والسنة لم يذكرا الذكاء الاصطناعي بطبيعة الحال، لكنه يدخل تحت باب الإتقان والعمل والاجتهاد، وهي أمور أمرنا بها الدين، والنبي صلى الله عليه وسلم قال: ‘الحكمة ضالة المؤمن أنى وجدها فهو أحق الناس بها.’”

 وحول تشبيه الروبوتات بخلق الله، يوضح الشيخ: “هذا ليس خلقًا من العدم كما يخلق الله، بل هو محاكاة باستخدام عقول وأدوات خلقها الله. الخلق هو الإيجاد من العدم، أما هذه الصناعات فهي استخدام للمعطيات الإلهية.”

 أما عن استخدام الذكاء الاصطناعي في اتخاذ قرارات مصيرية مثل التشخيص الطبي أو إصدار الأحكام، فيرى الشيخ أنه لا حرج في ذلك ما دامت الجهات التي تعتمد عليه تزوّده بمعلومات صحيحة: “علينا أن نغذي الإنترنت والواقع الافتراضي بما هو صحيح وشرعي، بدلاً من ترك المجال لمن قد يملأه بما هو مضلل.”

 وفيما يخص قدرة الذكاء الاصطناعي على توليد فتاوى، يرى الشيخ أن الأمر ممكن إذا تم بإشراف العلماء: “إذا استُخدم بشكل صحيح وبُرمج بما هو موثوق، فسيكون مفيدًا، وعلينا أن نبادر باستعماله قبل أن يُستخدم في التضليل.”

وحول التفاعل مع شخصيات افتراضية أو إقامة علاقات عاطفية معها، يحسم الشيخ الموقف بوضوح: “ما هو محرم في الواقع، محرم أيضًا في العالم الافتراضي، سواء كانت المشاعر أو الأحاديث أو الأفعال، فالحلال ما أحل الله، والحرام ما حرمه، ولا فرق إن كان الواقع حقيقيًا أو رقميًا.”

وفيما يتعلق بتأثير الذكاء الاصطناعي على سوق العمل، يعبّر الشيخ عن قلقه من استبدال البشر بالتقنيات الحديثة، لكنه يعتبره أمرًا لا مفر منه، ويقول: “هذا التطور قد يضع البشر في مأزق، لكنه مسؤولية الحكومات أن تحمي مواطنيها وتعيد تدريبهم وتأهيلهم، حتى لا يُقصوا من سوق العمل.”

 ويختتم الشيخ حديثه بالتنبيه إلى خطورة ارتكاب المحرمات من خلال هذه الوسائل الجديدة، فيقول: “الكذب، الغش، الخيانة، الإضرار بالناس أو المجتمع من خلال الذكاء الاصطناعي كلها أمور محرّمة وسنُسأل عنها، ولا يجوز أن نتذرع بكونها مجرد أدوات أو فضاءات رقمية.”

 بهذا الرأي الشامل، يوضح الشيخ د. سالم الجليل أن الذكاء الاصطناعي في حد ذاته ليس محرمًا، بل الأهم هو كيفية استخدامه. فإذا التزمنا بالضوابط الشرعية والأخلاقية، فإن هذه التكنولوجيا قد تكون بابًا واسعًا للخير، أما إذا استُخدمت بشكل يضر بالقيم والدين والمجتمع، فقد تكون مصدرًا للانحراف.

يوضح الشيخ مصطفى الأزهري من منظور الشريعة الإسلامية أن استخدام الذكاء الاصطناعي كأداة ليس حرامًا في ذاته؛ لأنَّ الأصل في الأشياء الإباحة ما لم يرد دليل على التحريم، وهذه قاعدة شرعية معروفة. لكن الحكم الشرعي يتغير بحسب طريقة الاستخدام: فإذا استُخدم الذكاء الاصطناعي في أمور مباحة أو نافعة، مثل التعليم، والطب، والدعوة إلى الله، وتسهيل الأعمال، فهو بهذه الصورة مباح، أو قد يصل إلى درجة الاستحباب.

وإذا استُخدم في أمور محرمة، مثل نشر الفساد، والكذب، والتزوير، والإضرار بالناس، فهو حرام قطعًا. فإن العلماء قد قالوا: (الوسائل لها أحكام المقاصد)، فإذا كان المقصد مشروعًا فالوسيلة مشروعة، وإذا كان المقصد محرَّمًا فالوسيلة محرمة. والله أعلم.

ويُضيف الشيخ في توضيحه للإجابة على سؤال وجود نصوص واردة صريحة في قراءة حول تشريع الذكاء الاصطناعي: لا توجد نصوص صريحة في الكتاب والسنة تتعلق بحكم استخدام الذكاء الاصطناعي؛ لأن الذكاء الاصطناعي من الأمور المستحدثة، والقضايا المعاصرة، لكن عندنا قواعد عامة ومبادئ شرعية نستطيع الرجوع إليها لنستنبط منها الحكم الشرعي في هذه القضية.

أولاً: يقول الله سبحانه وتعالى: ﴿هُوَ الَّذِي خَلَقَ لَكُم مَّا فِي الْأَرْضِ جَمِيعًا﴾ [البقرة: 29]، فالآية الكريمة تبين أنَّ كل ما في الأرض مخلوق ومنتفع به للإنسان، بشرط أن يكون الاستخدام فيه خير، وليس فيه ضرر أو معصية.

ثانيًا: قال رسول الله ﷺ: «لا ضرر ولا ضرار» [رواه ابن ماجه وغيره]. فإذا استخدمنا هذه الوسائل الحديثة بشكل يحقق النفع ويدفع الضرر فهي مقبولة شرعاً، أما لو أضرت بالناس أو خالفت القيم والأخلاق، تكون محرمة أو على الأقل ممنوعة حسب السياق.

ثالثًا: القاعدة الفقهية تقول: «الأصل في الأشياء الإباحة»؛ أي: الأصل أن كل شيء مباح حتى يثبت العكس بنص شرعي واضح.

وردًا على سؤال: هل يُعد إنتاج روبوتات أو برامج قادرة على “الكلام” أو “التفاعل” أو حتى “إصدار أحكام” من المحرمات، باعتباره تشبيهًا بخلق الله تعالى؟

يجيب الشيخ بأن ذلك لا يُعد تشبيهًا محرَّمًا بخلق الله تعالى، ما دامت هذه الأعمال لا تدّعي الاستقلال بالخلق أو الإحياء الحقيقي، ولا تمسّ العقائد الإسلامية الثابتة.

ويُفصّل الشيخ ذلك قائلًا:

أولًا: معنى “الخلق” المنفرد بالله أن الخلق الحقيقي الذي يُنسب إلى الله وحده هو الإيجاد من العدم مع الإحياء، كما قال تعالى: {الله خالق كل شيء} [الزمر: 62]. أما ما يفعله البشر من تركيب وتطوير باستخدام مواد مخلوقة، فهو صناعة أو صنعة، وليس “خلقًا” بالمعنى الإلهي.

ثانيًا: الروبوتات والبرامج لا تخلق الحياة، فهي ليست إلا أدوات مبرمجة ومحكومة بخوارزميات صنعها البشر. “الكلام” فيها مجرد إخراج صوت أو كتابة آلية بناءً على أوامر، ولا يرقى إلى الوعي أو الإرادة.

ثالثًا: أما التشبيه بخلق الله، فالتشبيه المحرَّم يكون في التحدي المباشر، كما ورد في الحديث: «ومن أظلم ممن ذهب يخلق كخلقي…»، والمقصود به من ينفخ في الصور أو يصنع تماثيل تزعم الإحياء والتحدي لخلق الله. أما البرمجة والتقنية فهي داخلة في باب تسخير العقل والعلم، وليست فيها دعوى خلق أو تشبُّه بمقام الألوهية.

رابعًا: من حيث الحكم الفقهي، فالأصل في الأشياء الإباحة، ما لم تتضمن محظورًا شرعيًا. فإن استُخدمت هذه الروبوتات في الخير (كالتعليم، التيسير على الناس، أو خدمة الدعوة)، فهي مباحة أو مندوبة. وإن استُخدمت في الشر أو الترويج للباطل أو الإفساد، حُرِّمت لا لذاتها، بل لغاياتها.

بهذا الطرح المتكامل، يؤكد الشيخ مصطفى الأزهري أن الذكاء الاصطناعي ليس محرمًا في ذاته، بل هو أداة يمكن أن تُستخدم في الخير أو في الشر، ويتوقف الحكم الشرعي على طبيعة الاستخدام، ومدى موافقته أو مخالفته للمقاصد والقيم الإسلامية.

شكرًا لمشاركتك النص، وها هو رأي القس يوسف ذكي بعد إعادة الصياغة الكاملة، مع الحفاظ على كل المعلومات الأصلية، وجعله مناسبًا للإدراج في مادة صحفية متماسكة:

 القس يوسف ذكي: موقف الكنيسة من الذكاء الاصطناعي

 يؤكد القس يوسف ذكي أن الذكاء الاصطناعي ليس شيئًا محرّمًا أو خاطئًا في ذاته، بل هو أداة يمكن للإنسان أن يستخدمها في الخير أو الشر، بحسب نيته وطريقة استخدامه. ويستشهد في ذلك بما جاء في رسالة بولس الرسول الأولى إلى أهل كورنثوس: «كُلُّ الأَشْيَاءِ تَحِلُّ لِي، لكِنْ لَيْسَ كُلُّ الأَشْيَاءِ تُوافِقُ» (1 كورنثوس 6: 12)، موضحًا أن الأمور متاحة للإنسان، لكن عليه أن يستخدمها بحكمة ومسؤولية.

 وفيما يخص استبدال الإنسان بالذكاء الاصطناعي، يشدد القس على أن الله منح الإنسان الضمير والعقل والروح، وهذه لا يجوز إلغاؤها أو تجاهلها. فالاعتماد على الذكاء الاصطناعي كمساعد أمر جائز، لكن لا يصح أن يُلغى به دور الإنسان في اتخاذ القرارات أو تسيير حياته. ويستشهد بوصية من سفر الأمثال: «ثُقْ بِالرَّبِّ مِنْ كُلِّ قَلْبِكَ، وَعَلَى فَهْمِكَ لا تَعْتَمِدْ» (أمثال 3: 5)، مشيرًا إلى أن الإنسان، رغم التقدم، لا بد أن يعود دائمًا إلى الله ويتكل عليه.

 ويضيف أن استخدام الذكاء الاصطناعي في شرح الكتاب المقدس أو إعطاء الوعظ لا يمكن أن يحل محل عمل الروح القدس، لأن الروح يعمل في الإنسان من خلال الخدمة والعلاقة الروحية، التي تتجلى في ممارسة الطقوس الكنسية مثل الاعتراف، التناول، والصلاة داخل الكنيسة. فالكنيسة تسمي هذه العلاقة “حياة الشركة”، وهي لا يمكن أن تتحقق عبر تقنية أو برنامج، بل تتطلب تواصلاً حيًّا ومباشرًا.

 ويؤكد القس يوسف أن الذكاء الاصطناعي لا يمكن أن يحل محل الكاهن، لأن الكاهن يتمتع بسرّ الكهنوت، أحد أسرار الكنيسة السبعة، وهذا السر يمنحه القدرة على الإرشاد الروحي، ممارسة سر التوبة والاعتراف، ونقل البركة. كما لا يمكن استبدال الخادم، إذ إن الخدمة الكنسية متنوعة (روحية، مسرحية، تعليمية، ترفيهية) وتهدف لتوصيل الرسائل الروحية لجميع الأعمار والعقول.

 ويستشهد القس بآيات من الكتاب المقدس يستند عليها استخدام الذكاء الاصطناعي:

  • «امْتَحِنُوا كُلَّ شَيْءٍ. تَمَسَّكُوا بِالْحَسَنِ» (1 تسالونيكي 5: 21)
  • «كُلُّ مَا فِي الْعَالَمِ … لَيْسَ مِنَ الآبِ، بَلْ مِنَ الْعَالَمِ» (1 يوحنا 2: 16)، مشيرًا إلى أن التكنولوجيا ليست من خلق الله مباشرة، بل من صنع الإنسان، وقد تشوبها أخطاء.

 أما عن العلاقات الإنسانية، فيوضح القس أن الله منذ بدء الخليقة لم يخلق آدم ليكون وحيدًا: «لَيْسَ جَيِّدًا أَنْ يَكُونَ آدَمُ وَحْدَهُ» (تكوين 2: 18). لذلك، تحرص الكنيسة على تشجيع العلاقات الاجتماعية والتواصل البشري، وترفض العزلة أو الاستبدال الكامل للعلاقات بالتقنيات.

 ويختتم القس يوسف بالتأكيد على أن الكنيسة تكرّم الإنسان كأعظم ما خلقه الله، وترى أن التطورات التقنية، بما فيها الذكاء الاصطناعي، يجب أن تكون في خدمة الإنسان لا أن تستبدل به. ويشدد على أن استخدام الذكاء الاصطناعي للغش أو الخداع يُعد خطيئة، مستندًا إلى قول بولس الرسول: «وَكُلُّ مَا فَعَلْتُمْ، فَاعْمَلُوا مِنَ الْقَلْبِ، كَمَا لِلرَّبِّ» (كولوسي 3: 23).

 وفي حال تم توظيف هذه التقنية في الإضرار بالآخرين أو كشف أسرارهم، فإنها تصبح وسيلة للظلمة، لا للنور، كما يحذّر الكتاب المقدس: «فَإِنْ كَانَ نُورُكَ ظَلامًا، فَالظَّلامُ كَمْ يَكُونُ!» (متى 6: 23).

“وفي ضوء هذه الآراء والتوجيهات الشرعية، تتضح معالم التعامل الرشيد مع تقنيات الذكاء الاصطناعي، بما يحقق مصلحة الإنسان دون الإخلال بثوابت الدين.”

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