If you wish for a computer to be able to sign commits but not push (or push commits but not sign) that would be impossible. Anytime you use that public key (fo

If you wish for a computer to be able to sign commits but not push (or push commits but not sign) that would be impossible. Anytime you use that public key (for example, to SSH into a server) that session is linked to your identity via git commits (this doesn't actually matter for github, as github exposes all your SSH keys via its API anyways).