def __del__(self):
     if OpenSSL._hexversion > 0x10100000 and not OpenSSL._libreSSL:
         OpenSSL.EVP_CIPHER_CTX_reset(self.ctx)
     else:
         OpenSSL.EVP_CIPHER_CTX_cleanup(self.ctx)
     OpenSSL.EVP_CIPHER_CTX_free(self.ctx)