Microsoft Challenge Handshake Authentication Protocol (MS-CHAP)
Microsoft created MS-CHAP to authenticate remote Windows workstations, providing the functionality to which LAN-based users are accustomed while integrating the hashing algorithms used on Windows networks. Like CHAP, MS-CHAP uses a challenge-response mechanism to keep the password from being sent during the authentication process.
MS-CHAP uses the Message Digest 4 (MD4) hashing algorithm and the Data Encryption Standard (DES) encryption algorithm to generate the challenge and response and provides mechanisms for reporting connection errors and for changing the user's password. The response packet is in a format specifically designed to work with networking products in Windows 95, Windows 98, Windows Millennium Edition, Windows NT, Windows 2000, and Windows XP.