1) Appraiser 2) Critic 1) Notary 
An authenticator is a way to prove to a computer system that you really are who you are (called authentication). It is either: Authenticator tokens are common when one program needs to authenticate itself to a larger server or cloud repeatedly. For instance, you (the human) might sign on to a secure website with your name and password, after which...
noun one who determines authenticity (as of works of art) or who guarantees validity
a person or thing that authenticates. · a code used to authenticate a previously transmitted code.