Add __eq__ and missing properties

CHANGELOG.rst

@@ -18,6 +18,18 @@ Changelog
 * Removed the deprecated ``CAST5``, ``SEED``, ``IDEA``, and ``Blowfish``
   classes from the cipher module. These are still available in
   :doc:`/hazmat/decrepit/index`.
+* Make instances of
+  :class:`~cryptography.hazmat.primitives.hashes.HashAlgorithm` as well as
+  instances of classes in
+  :mod:`~cryptography.hazmat.primitives.asymmetric.padding`
+  comparable.
+* Added `salt_length` property to
+  :class:`~cryptography.hazmat.primitives.asymmetric.padding.PSS`.
+* Added `label` property to
+  :class:`~cryptography.hazmat.primitives.asymmetric.padding.OAEP`.
+* Added `algorithm` property to
+  :class:`~cryptography.hazmat.primitives.asymmetric.padding.MGF1`.
+
 
 .. _v45-0-6:
 

docs/hazmat/primitives/asymmetric/cloudhsm.rst

@@ -88,7 +88,7 @@ if you only need a subset of functionality.
     ...         Maps the cryptography padding and algorithm to the corresponding KMS signing algorithm.
     ...         This is specific to your implementation.
     ...         """
-    ...         if isinstance(padding, PKCS1v15) and isinstance(algorithm, hashes.SHA256):
+    ...         if padding == PKCS1v15() and algorithm == hashes.SHA256():
     ...             return b"RSA_PKCS1_V1_5_SHA_256"
     ...         else:
     ...             raise NotImplementedError()

docs/hazmat/primitives/asymmetric/rsa.rst

@@ -325,6 +325,14 @@ Padding
 
         The padding's mask generation function (MGF).
 
+    .. attribute:: salt_length
+
+        :type: int
+
+        .. versionadded:: 46.0.0
+
+        The length of the salt.
+
 .. class:: OAEP(mgf, algorithm, label)
 
     .. versionadded:: 0.4
@@ -351,6 +359,14 @@ Padding
 
         The padding's hash algorithm.
 
+    .. attribute:: label
+
+        :type: bytes | None
+
+        .. versionadded:: 42.0.0
+
+        The padding's hash algorithm.
+
     .. attribute:: mgf
 
         :type: :class:`~cryptography.hazmat.primitives.asymmetric.padding.MGF`
@@ -411,6 +427,14 @@ Mask generation functions
     :param algorithm: An instance of
         :class:`~cryptography.hazmat.primitives.hashes.HashAlgorithm`.
 
+    .. attribute:: algorithm
+
+        :type: :class:`~cryptography.hazmat.primitives.hashes.HashAlgorithm`.
+
+        .. versionadded:: 46.0.0
+
+        The algorithm of this instance.
+
 Numbers
 ~~~~~~~
 

docs/x509/reference.rst

@@ -248,7 +248,7 @@ Loading Certificate Revocation Lists
         >>> from cryptography import x509
         >>> from cryptography.hazmat.primitives import hashes
         >>> crl = x509.load_pem_x509_crl(pem_crl_data)
-        >>> isinstance(crl.signature_hash_algorithm, hashes.SHA256)
+        >>> crl.signature_hash_algorithm == hashes.SHA256()
         True
 
 .. function:: load_der_x509_crl(data)
@@ -287,7 +287,7 @@ Loading Certificate Signing Requests
         >>> from cryptography import x509
         >>> from cryptography.hazmat.primitives import hashes
         >>> csr = x509.load_pem_x509_csr(pem_req_data)
-        >>> isinstance(csr.signature_hash_algorithm, hashes.SHA256)
+        >>> csr.signature_hash_algorithm == hashes.SHA256()
         True
 
 .. function:: load_der_x509_csr(data)
@@ -477,7 +477,7 @@ X.509 Certificate Object
         .. doctest::
 
             >>> from cryptography.hazmat.primitives import hashes
-            >>> isinstance(cert.signature_hash_algorithm, hashes.SHA256)
+            >>> cert.signature_hash_algorithm == hashes.SHA256()
             True
 
     .. attribute:: signature_algorithm_oid
@@ -716,7 +716,7 @@ X.509 CRL (Certificate Revocation List) Object
         .. doctest::
 
             >>> from cryptography.hazmat.primitives import hashes
-            >>> isinstance(crl.signature_hash_algorithm, hashes.SHA256)
+            >>> crl.signature_hash_algorithm == hashes.SHA256()
             True
 
     .. attribute:: signature_algorithm_oid
@@ -1119,7 +1119,7 @@ X.509 CSR (Certificate Signing Request) Object
         .. doctest::
 
             >>> from cryptography.hazmat.primitives import hashes
-            >>> isinstance(csr.signature_hash_algorithm, hashes.SHA256)
+            >>> csr.signature_hash_algorithm == hashes.SHA256()
             True
 
     .. attribute:: signature_algorithm_oid

src/cryptography/hazmat/primitives/asymmetric/padding.py

@@ -5,6 +5,7 @@
 from __future__ import annotations
 
 import abc
+import typing
 
 from cryptography.hazmat.primitives import hashes
 from cryptography.hazmat.primitives._asymmetric import (
@@ -16,6 +17,9 @@
 class PKCS1v15(AsymmetricPadding):
     name = "EMSA-PKCS1-v1_5"
 
+    def __eq__(self, other: typing.Any) -> bool:
+        return isinstance(other, PKCS1v15)
+
 
 class _MaxLength:
     "Sentinel value for `MAX_LENGTH`."
@@ -56,10 +60,26 @@ def __init__(
 
         self._salt_length = salt_length
 
+    def __eq__(self, other: typing.Any) -> bool:
+        if isinstance(self._salt_length, int):
+            eq_salt_length = self._salt_length == other._salt_length
+        else:
+            eq_salt_length = self._salt_length is other._salt_length
+
+        return (
+            isinstance(other, PSS)
+            and eq_salt_length
+            and self._mgf == other._mgf
+        )
+
     @property
     def mgf(self) -> MGF:
         return self._mgf
 
+    @property
+    def salt_length(self) -> int | _MaxLength | _Auto | _DigestLength:
+        return self._salt_length
+
 
 class OAEP(AsymmetricPadding):
     name = "EME-OAEP"
@@ -77,10 +97,22 @@ def __init__(
         self._algorithm = algorithm
         self._label = label
 
+    def __eq__(self, other: typing.Any) -> bool:
+        return (
+            isinstance(other, OAEP)
+            and self._mgf == other._mgf
+            and self._algorithm == other._algorithm
+            and self._label == other._label
+        )
+
     @property
     def algorithm(self) -> hashes.HashAlgorithm:
         return self._algorithm
 
+    @property
+    def label(self) -> bytes | None:
+        return self._label
+
     @property
     def mgf(self) -> MGF:
         return self._mgf
@@ -89,6 +121,13 @@ def mgf(self) -> MGF:
 class MGF(metaclass=abc.ABCMeta):
     _algorithm: hashes.HashAlgorithm
 
+    @abc.abstractmethod
+    def __eq__(self, other: typing.Any) -> bool:
+        """
+        Implement equality checking.
+        """
+        ...
+
 
 class MGF1(MGF):
     def __init__(self, algorithm: hashes.HashAlgorithm):
@@ -97,6 +136,13 @@ def __init__(self, algorithm: hashes.HashAlgorithm):
 
         self._algorithm = algorithm
 
+    def __eq__(self, other: typing.Any) -> bool:
+        return isinstance(other, MGF1) and self._algorithm == other._algorithm
+
+    @property
+    def algorithm(self) -> hashes.HashAlgorithm:
+        return self._algorithm
+
 
 def calculate_max_pss_salt_length(
     key: rsa.RSAPrivateKey | rsa.RSAPublicKey,