Since key certification is more frequently referred to as key signing, the method used to perform this function is key_sign.

The key_sign method takes four arguments: key, uids, expires_in and local. The default value of uids is None and which results in all user IDs being selected. The default value of both expires_in and local is False; which results in the signature never expiring and being able to be exported.

The key is the key being signed rather than the key doing the signing. To change the key doing the signing refer to the signing key selection above for signing messages and files.

If the uids value is not None then it must either be a string to match a single user ID or a list of strings to match multiple user IDs. In this case the matching of those strings must be precise and it is case sensitive.

To sign Danger Mouse's key for just the initial user ID with a signature which will last a little over a month, do this:

import gpg c = gpg.Context() uid = "Danger Mouse <dm@secret.example.net>" dmfpr = "177B7C25DB99745EE2EE13ED026D2F19E99E63AA" key = c.get_key(dmfpr, secret=True) c.key_sign(key, uidsuid, expires_in=2764800)