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)
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