. Cyber identities are most easy to fake, one is rarely too sure of the identity of his conversation partner. Identities are determined based on: explicit display (password, PIN, key) implicit display (non-repeat identifier) Multi parametric identification. Determination of identity is probabilistic: happens when the probability to be wrong is sufficiently small (never zero). It's good practice to employ a mutual identification procedure, to insure each of the identity of the other.