Definicja Microsoft NT LAN Manager

Windows NT authentication protocol that uses a challenge and response algorithm for authenticating users within a Windows NT network.

The Microsoft NT LAN Manager sets up credentials for the user that are obtained during an interactive logon process. The credentials consist of a domain name, a user name, and a one-way hash of the user's password.

Afterwards, the NTLM uses an encrypted challenge/response procedure to authenticate the user without transmitting the user's password. Instead, the system requesting authentication must perform a calculation that proves it has access to the secured NTLM credentials.