Signature Verification Issue Due to Missing Cryptography Backend Functions

[arv1ndh]

Installing pykmip==0.10.0 also installs cryptography=42.0.4

Cryptography 42.0.2 does not have the following functions, load_der_public_key and load_pem_public_key in the instance created by default_backend().

>>> import cryptography
>>> cryptography.__version__
'42.0.2'
>>> import kmip
>>> kmip.__version__
'0.10.0'
>>> from cryptography.hazmat.backends import default_backend
>>> backend = default_backend()
>>> backend.load_der_public_key(b"test")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'Backend' object has no attribute 'load_der_public_key'
>>> backend.load_pem_public_key(b"test")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'Backend' object has no attribute 'load_pem_public_key'
>>>

This is causing the kmip_server to throw, "Signing bytes could not be loaded" when there is an attempt to verify a signature using a public_key.

Code using older cryptography functions

kmip/services/server/crypto/engine.py

1490             try:
1491                 public_key = backend.load_der_public_key(signing_key)
1492             except Exception:
1493                 try:
1494                     public_key = backend.load_pem_public_key(signing_key)
1495                 except Exception:
1496                     raise exceptions.CryptographicFailure(
1497                         "The signing key bytes could not be loaded."
1498                     )