revocation_logic.py

        def _can_revoke(revoker, target):
            if revoker.is_primary and revoker.fingerprint == target.fingerprint:
                return True
            self_sigs = target.self_signatures if target.is_primary else target.parent.self_signatures
            for self_sig in self_sigs:
                for rk in self_sig.revocation_key:
                    if rk.algorithm == revoker.key_algorithm and rk.fingerprint == revoker.fingerprint:
                        return True
            return False

        hash_algo = prefs.pop('hash', None)
        sig_type = None
        if isinstance(target, PGPUID):
            sig_type = SignatureType.CertRevocation

        elif isinstance(target, PGPKey):
            # Check that we are revoking a key we can revoke.
            if _can_revoke(self, target):
                sig_type = SignatureType.KeyRevocation if target.is_primary else sig_type = Signature.SubkeyRevocation

        else:  # pragma: no cover
            raise TypeError

        if sig_type is None:
            raise PGPError("Can't revoke the given key with this key.")