def final(self):
i = OpenSSL.c_int(0)
buffer = OpenSSL.malloc(b"", self.cipher.get_blocksize())
if (OpenSSL.EVP_CipherFinal_ex(self.ctx, OpenSSL.byref(buffer),
OpenSSL.byref(i))) == 0:
raise Exception("[OpenSSL] EVP_CipherFinal_ex FAIL ...")
return buffer.raw[0:i.value]
