Next year, I intend to have a new role, Certificate Authority, the man who is responsible to sign public key. I forgot this task for a while and xkcd reminded me in last minute of this year. Certificate Authority aka CA is just a part of Public Key Infrastructure aka PKI. CAs don't know anything, one thing they do is to sign public keys which are verified by a Registration Authority aka RA. RA must verify the application form of each requester one by one, face to face by comparing his/her face to his/her photo ID. Anyway, CA might be RA at the same time to simply communication between this 2 parties.