rsa.py 文件源码

def _enc_dec_rsa(backend, key, data, padding):
    if not isinstance(padding, AsymmetricPadding):
        raise TypeError("Padding must be an instance of AsymmetricPadding.")

    if isinstance(padding, PKCS1v15):
        padding_enum = backend._lib.RSA_PKCS1_PADDING
    elif isinstance(padding, OAEP):
        padding_enum = backend._lib.RSA_PKCS1_OAEP_PADDING
        if not isinstance(padding._mgf, MGF1):
            raise UnsupportedAlgorithm(
                "Only MGF1 is supported by this backend.",
                _Reasons.UNSUPPORTED_MGF
            )

        if not isinstance(padding._mgf._algorithm, hashes.SHA1):
            raise UnsupportedAlgorithm(
                "This backend supports only SHA1 inside MGF1 when "
                "using OAEP.",
                _Reasons.UNSUPPORTED_HASH
            )

        if padding._label is not None and padding._label != b"":
            raise ValueError("This backend does not support OAEP labels.")

        if not isinstance(padding._algorithm, hashes.SHA1):
            raise UnsupportedAlgorithm(
                "This backend only supports SHA1 when using OAEP.",
                _Reasons.UNSUPPORTED_HASH
            )
    else:
        raise UnsupportedAlgorithm(
            "{0} is not supported by this backend.".format(
                padding.name
            ),
            _Reasons.UNSUPPORTED_PADDING
        )

    if backend._lib.Cryptography_HAS_PKEY_CTX:
        return _enc_dec_rsa_pkey_ctx(backend, key, data, padding_enum)
    else:
        return _enc_dec_rsa_098(backend, key, data, padding_enum)