if you have never read papers on cryptography you can't understand, there's typically 2 people, the intended users of the protocol, and Eve some attacker of the

if you have never read papers on cryptography you can't understand, there's typically 2 people, the intended users of the protocol, and Eve some attacker of the protocol, since these roles re-occur in different problems, the scientific community has settled on this lingo such that the reader can immediately understand which problem for whom we are trying to solve. I.e. a cryptographer reading about a new protocol would immediately understand the paper tries to solve Alice and Bob's problem...