Webopedia on Google+Webopedia on TwitterWebopedia on FacebookTech Bytes Blog
Main » TERM » C »

CHAP

Short for Challenge Handshake Authentication Protocol, a type of authentication in which the authentication agent (typically a network server) sends the client program a random value that is used only once and an ID value. Both the sender and peer share a predefined secret. The peer concatenates the random value (or nonce), the ID and the secret and calculates a one-way hash using MD5. The hash value is sent to the authenticator, which in turn builds that same string on its side, calculates the MD5 sum itself and compares the result with the value received from the peer. If the values match, the peer is authenticated.

By transmitting only the hash, the secret can't be reverse-engineered. The ID value is increased with each CHAP dialogue to protect against replay attacks.

Contrast with PAP.







TECH RESOURCES FROM OUR PARTNERS
DID YOU KNOW?
The Five Generations of Computers

Learn about each of the five generations of computers and major technology developments that have led to the current devices that we use today. Read More »

Cloud Computing Market Leaders, 2015

If not for AWS, Microsoft would dominate the cloud. The race to capture market share will grow ever more fierce in the years ahead. Here's a look... Read More »

OpenStack Brings Liberty to the Cloud

Massive changes set to come to the cloud as Big Tent model lands in widely deployed cloud platform used by Walmart, Comcast, AT&T, Time Warner... Read More »

QUICK REFERENCE
29 Free Android Apps for Cash-Strapped Students

From wacky alarm clocks to lecture hall tools and after class entertainment, these Android apps are a good fit for a student's life and budget. Read More »

Network Fundamentals Study Guide

A network is a group of two or more computer systems or devices, linked together to share resources, exchange files and electronic communications.... Read More »

Computer Architecture Study Guide

This Webopedia  study guide describes the different parts of a computer system and their relations. Read More »