tests: Use ECDSA keys in tests

The ECDSA keys are much more lightweight, faster to generate and
use, while very compatible with various environments including FIPS.

This brings the time to complete the whole testsuite on my machine from
22s to 4s.

Signed-off-by: Jakub Jelen <jjelen@redhat.com>

Author: Jakuje

tests/conftest.py

@@ -76,8 +76,8 @@ def sshd_hostkey_path(sshd_path):
 
     # noqa: DAR101
     """
-    path = sshd_path / 'ssh_host_rsa_key'
-    keygen_cmd = 'ssh-keygen', '-N', '', '-f', str(path)
+    path = sshd_path / 'ssh_host_ecdsa_key'
+    keygen_cmd = 'ssh-keygen', '-N', '', '-f', str(path), '-b', '256'
     subprocess.check_call(keygen_cmd)
     path.chmod(_FILE_PRIV_RW_OWNER)
     return path
@@ -92,11 +92,11 @@ def ssh_clientkey_path(sshd_path):
 
     # noqa: DAR101
     """
-    path = sshd_path / 'ssh_client_rsa_key'
+    path = sshd_path / 'ssh_client_ecdsa_key'
     keygen_cmd = (  # noqa: WPS317
         'ssh-keygen',
-        '-t', 'rsa',
-        '-b', '8192',
+        '-t', 'ecdsa',
+        '-b', '256',
         '-C', 'ansible-pylibssh integration tests key',
         '-N', '',
         '-f', str(path),