Authenticator
From FreeRADIUS Wiki
In telecommunications, an authenticator is a symbol or group of symbols, or a series of bits, selected or derived in a prearranged manner and usually inserted at a predetermined point within a smessage or transmission for the purpose of attesting to the validity of the message or transmission. A letter, numeral, group of letters or numerals, or any combinations of these, attesting to the authenticity of a message or transmission.
In IEEE 802.1X, an authenticator is an entity at one end of a point-to-point LAN segment that facilitates authentication of the entity attached to the other end of that link.
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