diff options
| -rw-r--r-- | cryptography/hazmat/primitives/asymmetric/padding.py | 21 | ||||
| -rw-r--r-- | docs/hazmat/primitives/asymmetric/padding.rst | 23 | ||||
| -rw-r--r-- | tests/hazmat/primitives/test_rsa.py | 27 |
3 files changed, 71 insertions, 0 deletions
diff --git a/cryptography/hazmat/primitives/asymmetric/padding.py b/cryptography/hazmat/primitives/asymmetric/padding.py index 6bafe314..46e00b8e 100644 --- a/cryptography/hazmat/primitives/asymmetric/padding.py +++ b/cryptography/hazmat/primitives/asymmetric/padding.py @@ -13,6 +13,8 @@ from __future__ import absolute_import, division, print_function +import six + from cryptography import utils from cryptography.hazmat.primitives import interfaces @@ -20,3 +22,22 @@ from cryptography.hazmat.primitives import interfaces @utils.register_interface(interfaces.AsymmetricPadding) class PKCS1v15(object): name = "EMSA-PKCS1-v1_5" + + +class MGF1(object): + MAX_LENGTH = object() + + def __init__(self, algorithm, salt_length): + if not isinstance(algorithm, interfaces.HashAlgorithm): + raise TypeError("Expected instance of interfaces.HashAlgorithm.") + + self._algorithm = algorithm + + if (not isinstance(salt_length, six.integer_types) 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 diff --git a/docs/hazmat/primitives/asymmetric/padding.rst b/docs/hazmat/primitives/asymmetric/padding.rst index 7aec3bd3..8a034329 100644 --- a/docs/hazmat/primitives/asymmetric/padding.rst +++ b/docs/hazmat/primitives/asymmetric/padding.rst @@ -17,4 +17,27 @@ Padding PKCS1 v1.5 (also known as simply PKCS1) is a simple padding scheme developed for use with RSA keys. It is defined in :rfc:`3447`. +Mask Generation Functions +~~~~~~~~~~~~~~~~~~~~~~~~~ + +.. class:: MGF1(algorithm, salt_length) + + .. versionadded:: 0.3 + + MGF1 (Mask Generation Function 1) is used as the mask generation function + in :class:`PSS` padding. It takes a hash algorithm and a salt length. + + :param algorithm: An instance of a + :class:`~cryptography.hazmat.primitives.interfaces.HashAlgorithm` + provider. + + :param int salt_length: The length of the salt. It is recommended that this + be set to ``MGF1.MAX_LENGTH``. + + .. attribute:: MAX_LENGTH + + Pass this attribute to ``salt_length`` to get the maximum salt length + available. + + .. _`Padding is critical`: http://rdist.root.org/2009/10/06/why-rsa-encryption-padding-is-critical/ diff --git a/tests/hazmat/primitives/test_rsa.py b/tests/hazmat/primitives/test_rsa.py index 79323265..114dc415 100644 --- a/tests/hazmat/primitives/test_rsa.py +++ b/tests/hazmat/primitives/test_rsa.py @@ -558,3 +558,30 @@ class TestRSAVerification(object): public_key = private_key.public_key() with pytest.raises(TypeError): public_key.verifier(b"sig", "notpadding", hashes.SHA1(), backend) + + +class TestMGF1(object): + def test_invalid_hash_algorithm(self): + with pytest.raises(TypeError): + padding.MGF1(b"not_a_hash", 0) + + def test_invalid_salt_length_not_integer(self): + with pytest.raises(TypeError): + padding.MGF1(hashes.SHA1(), b"not_a_length") + + def test_invalid_salt_length_negative_integer(self): + with pytest.raises(ValueError): + padding.MGF1(hashes.SHA1(), -1) + + def test_valid_mgf1_parameters(self): + algorithm = hashes.SHA1() + salt_length = algorithm.digest_size + mgf = padding.MGF1(algorithm, salt_length) + assert mgf._algorithm == algorithm + assert mgf._salt_length == salt_length + + def test_valid_mgf1_parameters_maximum(self): + algorithm = hashes.SHA1() + mgf = padding.MGF1(algorithm, padding.MGF1.MAX_LENGTH) + assert mgf._algorithm == algorithm + assert mgf._salt_length == padding.MGF1.MAX_LENGTH |