automatic cert file name during keygen

pyseeder.py

@@ -23,7 +23,7 @@ def main():
             help="Identifier of certificate (example: user@mail.i2p)")
     kg_parser.add_argument("--private-key", default="data/priv_key.pem",
             help="RSA private key (default: data/priv_key.pem)")
-    kg_parser.add_argument("--cert", required=True, 
+    kg_parser.add_argument("--cert", default=None,
             help="Certificate (example: data/user_at_mail.i2p.crt)")
     kg_parser.set_defaults(func=pyseeder.actions.keygen)
 

pyseeder/actions.py

@@ -5,6 +5,9 @@ from pyseeder.utils import PyseederException, check_readable, check_writable
 
 def keygen(args):
     """Sub-command to generate keys"""
+    if not args.cert:
+        args.cert = "data/{}.crt".format(args.signer_id.replace("@", "_at_"))
+
     for f in [args.cert, args.private_key]: check_writable(f)
 
     from pyseeder.crypto import keygen