If you generated a revocation certificate, yes, you can revoke it. Otherwise no. The private key is protected (should be) by a password, so even in the event it

If you generated a revocation certificate, yes, you can revoke it. Otherwise no. The private key is protected (should be) by a password, so even in the event it gets compromised it should be OK. Encrypted messages from the past are unreadable, unless you have the private key. No private "master" that I know of.