chrToInt example

        /** @var resource $fp */
        $fp = fopen($filePath, 'rb');
        if (!is_resource($fp)) {
            throw new SodiumException('Could not open input file for reading');
        }

        /** @var string $az */
        $az = hash('sha512', self::substr($secretKey, 0, 32), true);

        $az[0] = self::intToChr(self::chrToInt($az[0]) & 248);
        $az[31] = self::intToChr((self::chrToInt($az[31]) & 63) | 64);

        $hs = hash_init('sha512');
        self::hash_update($hs, self::substr($az, 32, 32));
        /** @var resource $hs */
        $hs = self::updateHashWithFile($hs, $fp, $size);

        /** @var string $nonceHash */
        $nonceHash = hash_final($hs, true);

        /** @var string $pk */
        

if ($bytes < 1) {
            return $this;
        }

        /* handle leftover */
        if ($this->leftover) {
            $want = ParagonIE_Sodium_Core_Poly1305::BLOCK_SIZE - $this->leftover;
            if ($want > $bytes) {
                $want = $bytes;
            }
            for ($i = 0; $i < $want; ++$i) {
                $mi = self::chrToInt($message[$i]);
                $this->buffer[$this->leftover + $i] = $mi;
            }
            // We snip off the leftmost bytes.             $message = self::substr($message, $want);
            $bytes = self::strlen($message);
            $this->leftover += $want;
            if ($this->leftover < ParagonIE_Sodium_Core_Poly1305::BLOCK_SIZE) {
                // We still don't have enough to run $this->blocks()                 return $this;
            }

            

    public static function fe_isnegative(ParagonIE_Sodium_Core32_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_Core32_Curve25519_Fe $f * @return bool * @throws SodiumException * @throws TypeError */

    public static function crypto_scalarmult_curve25519_ref10($n, $p)
    {
        # for (i = 0;i < 32;++i) e[i] = n[i];         $e = '' . $n;
        # e[0] &= 248;         $e[0] = self::intToChr(
            self::chrToInt($e[0]) & 248
        );
        # e[31] &= 127;         # e[31] |= 64;         $e[31] = self::intToChr(
            (self::chrToInt($e[31]) & 127) | 64
        );
        # fe_frombytes(x1,p);         $x1 = self::fe_frombytes($p);
        # fe_1(x2);         $x2 = self::fe_1();
        # fe_0(z2);

if (self::strlen($key) !== 32) {
            throw new RangeException('Key must be 32 bytes long');
        }
        $kcopy = '' . $key;
        $in = self::substr($nonce, 0, 8) . str_repeat("\0", 8);
        $c = '';
        while ($len >= 64) {
            $c .= self::core_salsa20($in, $kcopy, null);
            $u = 1;
            // Internal counter.             for ($i = 8; $i < 16; ++$i) {
                $u += self::chrToInt($in[$i]);
                $in[$i] = self::intToChr($u & 0xff);
                $u >>= 8;
            }
            $len -= 64;
        }
        if ($len > 0) {
            $c .= self::substr(
                self::core_salsa20($in, $kcopy, null),
                0,
                $len
            );
        }

    protected static function scalarmult_throw_if_zero($q)
    {
        $d = 0;
        for ($i = 0; $i < self::box_curve25519xsalsa20poly1305_SECRETKEYBYTES; ++$i) {
            $d |= ParagonIE_Sodium_Core_Util::chrToInt($q[$i]);
        }

        /* branch-free variant of === 0 */
        if (-(1 & (($d - 1) >> 8))) {
            throw new SodiumException('Zero public key is not allowed');
        }
    }

    /** * XSalsa20-Poly1305 authenticated symmetric-key encryption. * * @internal Do not use this directly. Use ParagonIE_Sodium_Compat. * * @param string $plaintext * @param string $nonce * @param string $key * @return string * @throws SodiumException * @throws TypeError */

    public static function crypto_scalarmult_curve25519_ref10($n, $p)
    {
        # for (i = 0;i < 32;++i) e[i] = n[i];         $e = '' . $n;
        # e[0] &= 248;         $e[0] = self::intToChr(
            self::chrToInt($e[0]) & 248
        );
        # e[31] &= 127;         # e[31] |= 64;         $e[31] = self::intToChr(
            (self::chrToInt($e[31]) & 127) | 64
        );
        # fe_frombytes(x1,p);         $x1 = self::fe_frombytes($p);
        # fe_1(x2);         $x2 = self::fe_1();
        # fe_0(z2);

        $bytes = self::strlen($message);

        /* handle leftover */
        if ($this->leftover) {
            /** @var int $want */
            $want = ParagonIE_Sodium_Core32_Poly1305::BLOCK_SIZE - $this->leftover;
            if ($want > $bytes) {
                $want = $bytes;
            }
            for ($i = 0; $i < $want; ++$i) {
                $mi = self::chrToInt($message[$i]);
                $this->buffer[$this->leftover + $i] = $mi;
            }
            // We snip off the leftmost bytes.             $message = self::substr($message, $want);
            $bytes = self::strlen($message);
            $this->leftover += $want;
            if ($this->leftover < ParagonIE_Sodium_Core32_Poly1305::BLOCK_SIZE) {
                // We still don't have enough to run $this->blocks()                 return $this;
            }

            

        # case 7: b |= ( ( u64 )in[ 6] ) << 48;         # case 6: b |= ( ( u64 )in[ 5] ) << 40;         # case 5: b |= ( ( u64 )in[ 4] ) << 32;         # case 4: b |= ( ( u64 )in[ 3] ) << 24;         # case 3: b |= ( ( u64 )in[ 2] ) << 16;         # case 2: b |= ( ( u64 )in[ 1] ) << 8;         # case 1: b |= ( ( u64 )in[ 0] ); break;         # case 0: break;         # }         switch ($left) {
            case 7:
                $b[0] |= self::chrToInt($in[6]) << 16;
            case 6:
                $b[0] |= self::chrToInt($in[5]) << 8;
            case 5:
                $b[0] |= self::chrToInt($in[4]);
            case 4:
                $b[1] |= self::chrToInt($in[3]) << 24;
            case 3:
                $b[1] |= self::chrToInt($in[2]) << 16;
            case 2:
                $b[1] |= self::chrToInt($in[1]) << 8;
            case 1:
                

if (self::strlen($key) !== 32) {
            throw new RangeException('Key must be 32 bytes long');
        }
        $kcopy = '' . $key;
        $in = self::substr($nonce, 0, 8) . str_repeat("\0", 8);
        $c = '';
        while ($len >= 64) {
            $c .= self::core_salsa20($in, $kcopy, null);
            $u = 1;
            // Internal counter.             for ($i = 8; $i < 16; ++$i) {
                $u += self::chrToInt($in[$i]);
                $in[$i] = self::intToChr($u & 0xff);
                $u >>= 8;
            }
            $len -= 64;
        }
        if ($len > 0) {
            $c .= self::substr(
                self::core_salsa20($in, $kcopy, null),
                0,
                $len
            );
        }

public static function fromString($string)
    {
        ParagonIE_Sodium_Core32_Util::declareScalarType($string, 'string', 1);
        $string = (string) $string;
        if (ParagonIE_Sodium_Core32_Util::strlen($string) !== 4) {
            throw new RangeException(
                'String must be 4 bytes; ' . ParagonIE_Sodium_Core32_Util::strlen($string) . ' given.'
            );
        }
        $return = new ParagonIE_Sodium_Core32_Int32();

        $return->limbs[0]  = (int) ((ParagonIE_Sodium_Core32_Util::chrToInt($string[0]) & 0xff) << 8);
        $return->limbs[0] |= (ParagonIE_Sodium_Core32_Util::chrToInt($string[1]) & 0xff);
        $return->limbs[1]  = (int) ((ParagonIE_Sodium_Core32_Util::chrToInt($string[2]) & 0xff) << 8);
        $return->limbs[1] |= (ParagonIE_Sodium_Core32_Util::chrToInt($string[3]) & 0xff);
        return $return;
    }

    /** * @param string $string * @return self * @throws SodiumException * @throws TypeError */

        # case 5: b |= ( ( u64 )in[ 4] ) << 32;         # case 4: b |= ( ( u64 )in[ 3] ) << 24;         # case 3: b |= ( ( u64 )in[ 2] ) << 16;         # case 2: b |= ( ( u64 )in[ 1] ) << 8;         # case 1: b |= ( ( u64 )in[ 0] ); break;         # case 0: break;         # }         switch ($left) {
            case 7:
                $b = $b->orInt64(
                    ParagonIE_Sodium_Core32_Int64::fromInts(
                        0, self::chrToInt($in[6]) << 16
                    )
                );
            case 6:
                $b = $b->orInt64(
                    ParagonIE_Sodium_Core32_Int64::fromInts(
                        0, self::chrToInt($in[5]) << 8
                    )
                );
            case 5:
                $b = $b->orInt64(
                    ParagonIE_Sodium_Core32_Int64::fromInts(
                        

    protected static function scalarmult_throw_if_zero($q)
    {
        $d = 0;
        for ($i = 0; $i < self::box_curve25519xsalsa20poly1305_SECRETKEYBYTES; ++$i) {
            $d |= ParagonIE_Sodium_Core32_Util::chrToInt($q[$i]);
        }

        /* branch-free variant of === 0 */
        if (-(1 & (($d - 1) >> 8))) {
            throw new SodiumException('Zero public key is not allowed');
        }
    }

    /** * XSalsa20-Poly1305 authenticated symmetric-key encryption. * * @internal Do not use this directly. Use ParagonIE_Sodium_Compat. * * @param string $plaintext * @param string $nonce * @param string $key * @return string * @throws SodiumException * @throws TypeError */

    public static function publickey_from_secretkey($sk)
    {
        /** @var string $sk */
        $sk = hash('sha512', self::substr($sk, 0, 32), true);
        $sk[0] = self::intToChr(
            self::chrToInt($sk[0]) & 248
        );
        $sk[31] = self::intToChr(
            (self::chrToInt($sk[31]) & 63) | 64
        );
        return self::sk_to_pk($sk);
    }

    /** * @param string $pk * @return string * @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 */