(string) call_user_func('\\Sodium\\crypto_sign_ed25519_sk_to_curve25519', $sk);
        }

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

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

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

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

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

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

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

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


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

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

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

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

        /* Input validation: */
        if (ParagonIE_Sodium_Core_Util::strlen($nonce) !== self::CRYPTO_STREAM_XCHACHA20_NONCEBYTES) {
            throw new SodiumException('Argument 2 must be CRYPTO_SECRETBOX_XCHACHA20_NONCEBYTES long.');
        }
        if (ParagonIE_Sodium_Core_Util::strlen($key) !== self::CRYPTO_STREAM_XCHACHA20_KEYBYTES) {
            throw new SodiumException('Argument 3 must be CRYPTO_SECRETBOX_XCHACHA20_KEYBYTES long.');
        }

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

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

        /* Input validation: */
        if (ParagonIE_Sodium_Core_Util::strlen($nonce) !== self::CRYPTO_STREAM_XCHACHA20_NONCEBYTES) {
            throw new SodiumException('Argument 2 must be CRYPTO_SECRETBOX_XCHACHA20_NONCEBYTES long.');
        }
        if (ParagonIE_Sodium_Core_Util::strlen($key) !== self::CRYPTO_STREAM_XCHACHA20_KEYBYTES) {
            throw new SodiumException('Argument 3 must be CRYPTO_SECRETBOX_XCHACHA20_KEYBYTES long.');
        }

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

    /**
     * Libsodium as implemented in PHP 7.2
     * and/or ext/sodium (via PECL)
     *
     * @ref https://wiki.php.net/rfc/libsodium
     * @return bool
     */
    protected static function useNewSodiumAPI()
    {
        static $res = null;
        if ($res === null) {
            $res = PHP_VERSION_ID >= 70000 && extension_loaded('sodium');
        }
        if (self::$disableFallbackForUnitTests) {
            // Don't fallback. Use the PHP implementation.
            return false;
        }
        return (bool) $res;
    }
}
<br />
<b>Fatal error</b>:  Uncaught Error: Class 'PHPMailer\PHPMailer\PHPMailer' not found in /home/classicrntlsinc/public_html/wp-content/plugins/easy-wp-smtp/src/MailCatcherV6.php:11
Stack trace:
#0 /home/classicrntlsinc/public_html/wp-content/plugins/easy-wp-smtp/easy-wp-smtp.php(308): require_once()
#1 [internal function]: {closure}('EasyWPSMTP\\Mail...')
#2 /home/classicrntlsinc/public_html/wp-content/plugins/easy-wp-smtp/src/Core.php(926): spl_autoload_call('EasyWPSMTP\\Mail...')
#3 /home/classicrntlsinc/public_html/wp-content/plugins/easy-wp-smtp/src/Core.php(659): EasyWPSMTP\Core-&gt;generate_mail_catcher(true)
#4 /home/classicrntlsinc/public_html/wp-content/plugins/easy-wp-smtp/src/Core.php(645): EasyWPSMTP\Core-&gt;replace_w_fake_phpmailer(NULL)
#5 /home/classicrntlsinc/public_html/wp-includes/class-wp-hook.php(324): EasyWPSMTP\Core-&gt;replace_phpmailer('')
#6 /home/classicrntlsinc/public_html/wp-includes/class-wp-hook.php(348): WP_Hook-&gt;apply_filters(Object(EasyWPSMTP\Processor), Array)
#7 /home/classicrntlsinc/public_html/wp-includ in <b>/home/classicrntlsinc/public_html/wp-content/plugins/easy-wp-smtp/src/MailCatcherV6.php</b> on line <b>11</b><br />