ParagonIE_Sodium_Core_HChaCha20::hChaCha20

    public static function hChaCha20($in = '', $key = '', $c = null)
    {
        $ctx = array();

        if ($c === null) {
            $ctx[0] = 0x61707865;
            $ctx[1] = 0x3320646e;
            $ctx[2] = 0x79622d32;
            $ctx[3] = 0x6b206574;
        } else {
            $ctx[0] = self::load_4(self::substr($c,  0, 4));
            $ctx[1] = self::load_4(self::substr($c,  4, 4));
            $ctx[2] = self::load_4(self::substr($c,  8, 4));
            $ctx[3] = self::load_4(self::substr($c, 12, 4));
        }
        $ctx[4]  = self::load_4(self::substr($key,  0, 4));
        $ctx[5]  = self::load_4(self::substr($key,  4, 4));
        $ctx[6]  = self::load_4(self::substr($key,  8, 4));
        $ctx[7]  = self::load_4(self::substr($key, 12, 4));
        $ctx[8]  = self::load_4(self::substr($key, 16, 4));
        $ctx[9]  = self::load_4(self::substr($key, 20, 4));
        $ctx[10] = self::load_4(self::substr($key, 24, 4));
        $ctx[11] = self::load_4(self::substr($key, 28, 4));
        $ctx[12] = self::load_4(self::substr($in,   0, 4));
        $ctx[13] = self::load_4(self::substr($in,   4, 4));
        $ctx[14] = self::load_4(self::substr($in,   8, 4));
        $ctx[15] = self::load_4(self::substr($in,  12, 4));
        return self::hChaCha20Bytes($ctx);
    }