crypto.py 文件源码

def decrypt_pk(priv_key, ciphertext):
    """
    Decrypt a b64encoded ciphertext string with the RSA private key priv_key,
    using CryptoHash() as the OAEP/MGF1 padding hash.
    Returns the plaintext.
    Decryption failures result in an exception being raised.
    """
    try:
        plaintext = priv_key.decrypt(
            b64decode(ciphertext),
            padding.OAEP(
                mgf=padding.MGF1(algorithm=CryptoHash()),
                algorithm=CryptoHash(),
                label=None
                )
            )
    except UnsupportedAlgorithm as e:
        # a failure to dencrypt someone else's data is not typically a fatal
        # error, but in this particular case, the most likely cause of this
        # error is an old cryptography library
        logging.error("Fatal error: encryption hash {} unsupported, try upgrading to cryptography >= 1.4. Exception: {}".format(
                          CryptoHash, e))
        # re-raise the exception for the caller to handle
        raise e
    return plaintext