Challenge-Handshake Authentication Protocol: Difference between revisions

Revision as of 20:32, 15 November 2017

Revision as of 20:33, 15 November 2017

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In [[computing]], the '''Challenge-Handshake Authentication Protocol''' ('''CHAP''')) [[authentication|authenticates]] a user or network host to an authenticating entity. That entity may be, for example, an [[Internet service provider]]. CHAP is specified in {{IETF RFC|1994}}.

CHAP provides protection against [[replay attack]]s by the peer through the use of an incrementally changing identifier and of a variable challenge-value. CHAP requires that both the client and server know the plaintext of the secret, although it is never sent over the network. Thus, CHAP provides better security as compared to [[Password Authentication Protocol]] (PAP) which is vulnerable for both these reasons. The [[MS-CHAP]] variant does not require either peer to know the plaintext and does not transmit it, but has been broken.<ref>{{dead link|date=April 2017}}{{cite web