Challenge-Handshake Authentication Protocol: Difference between revisions

Revision as of 15:30, 5 July 2019

Revision as of 20:41, 15 July 2019

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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

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>{{cite web|url=https://www.cloudcracker.com/blog/2012/07/29/cracking-ms-chap-v2/|title=Divide and Conquer: Cracking MS-CHAPv2 with a 100% success rate|last=|first=|date=|year=2012|website=|publisher=[[DEF CON|David Hulton]]|archiveurl=https://web.archive.org/web/20160316174007/https://www.cloudcracker.com/blog/2012/07/29/cracking-ms-chap-v2/|archive-date=16 March 2016|accessdate=2013-03-10}}</ref>