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# This file is dual licensed under the terms of the Apache License, Version
# 2.0, and the BSD License. See the LICENSE file in the root of this repository
# for complete details.
import typing
from cryptography.hazmat.primitives import hashes
from cryptography.hazmat.primitives._asymmetric import AsymmetricPadding
from cryptography.hazmat.primitives.asymmetric import rsa
class PKCS1v15(AsymmetricPadding):
name = "EMSA-PKCS1-v1_5"
class PSS(AsymmetricPadding):
MAX_LENGTH = object()
name = "EMSA-PSS"
def __init__(self, mgf, salt_length):
self._mgf = mgf
if (
not isinstance(salt_length, int)
and salt_length is not self.MAX_LENGTH
):
raise TypeError("salt_length must be an integer.")
if salt_length is not self.MAX_LENGTH and salt_length < 0:
raise ValueError("salt_length must be zero or greater.")
self._salt_length = salt_length
class OAEP(AsymmetricPadding):
name = "EME-OAEP"
def __init__(
self,
mgf: "MGF1",
algorithm: hashes.HashAlgorithm,
label: typing.Optional[bytes],
):
if not isinstance(algorithm, hashes.HashAlgorithm):
raise TypeError("Expected instance of hashes.HashAlgorithm.")
self._mgf = mgf
self._algorithm = algorithm
self._label = label
class MGF1(object):
MAX_LENGTH = object()
def __init__(self, algorithm: hashes.HashAlgorithm):
if not isinstance(algorithm, hashes.HashAlgorithm):
raise TypeError("Expected instance of hashes.HashAlgorithm.")
self._algorithm = algorithm
def calculate_max_pss_salt_length(
key: typing.Union["rsa.RSAPrivateKey", "rsa.RSAPublicKey"],
hash_algorithm: hashes.HashAlgorithm,
) -> int:
if not isinstance(key, (rsa.RSAPrivateKey, rsa.RSAPublicKey)):
raise TypeError("key must be an RSA public or private key")
# bit length - 1 per RFC 3447
emlen = (key.key_size + 6) // 8
salt_length = emlen - hash_algorithm.digest_size - 2
assert salt_length >= 0
return salt_length
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