ParagonIE_Sodium_Core_XChaCha20::ietfStreamXorIc( string $message, string $nonce = '', string $key = '', string $ic = '' ): string

103    public static function ietfStreamXorIc($message, $nonce = '', $key = '', $ic = '')104    {105        if (self::strlen($nonce) !== 24) {106            throw new SodiumException('Nonce must be 24 bytes long');107        }108        return self::encryptBytes(109            new ParagonIE_Sodium_Core_ChaCha20_IetfCtx(110                self::hChaCha20(self::substr($nonce, 0, 16), $key),111                "\x00\x00\x00\x00" . self::substr($nonce, 16, 8),112                $ic113            ),114            $message115        );116    }