Switch debug logging in client.py to use key.fingerprint

[bskinn]

Per #396, FIPS mode rejects .get_fingerprint() because it uses MD5.

The .fingerprint property uses SHA256, which is FIPS-compatible.

This addresses the latest FIPS problem reported in #396. We'll see if it solves all the FIPS problems.

[bskinn]

@gubenkoved, can you test with my fork branch to see if this clears the path for FIPS?

[gubenkoved]

Hi @bskinn -- I've tested using this branch under FIPS-enabled OpenSSL, it seems to work!

root@170468b0597c:~# python3
Python 3.10.12 (main, Jun 11 2023, 05:26:28) [GCC 11.4.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import paramiko
>>> client = paramiko.client.SSHClient()
>>> client.set_missing_host_key_policy(paramiko.AutoAddPolicy())
>>> client.connect('10.29.24.3', username='admin', password='admin')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/local/lib/python3.10/dist-packages/paramiko/client.py", line 460, in connect
    self._policy.missing_host_key(
  File "/usr/local/lib/python3.10/dist-packages/paramiko/client.py", line 859, in missing_host_key
    key.get_name(), hostname, hexlify(key.get_fingerprint())
  File "/usr/local/lib/python3.10/dist-packages/paramiko/pkey.py", line 344, in get_fingerprint
    return md5(self.asbytes()).digest()
ValueError: [digital envelope routines] unsupported
...
root@170468b0597c:~# python3 -m pip install git+https://github.com/bskinn/paramiko.git@396-upgrade-log-fingerprints
root@170468b0597c:~# python3
Python 3.10.12 (main, Jun 11 2023, 05:26:28) [GCC 11.4.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import paramiko
>>> client = paramiko.client.SSHClient()
>>> client.set_missing_host_key_policy(paramiko.AutoAddPolicy())
>>> client.connect('10.29.24.3', username='admin', password='admin')