Ericsson Ericsson Nokia The Hypertext Transfer Protocol (HTTP) Authentication Framework includes two authentication schemes: Basic and Digest. Both schemes employ a shared secret based mechanism for access authentication. The Authentication and Key Agreement (AKA) mechanism performs user authentication and session key distribution in Universal Mobile Telecommunications System (UMTS) networks. AKA is a challenge- response based mechanism that uses symmetric cryptography. This memo specifies an AKA based one-time password generation mechanism for HTTP Digest access authentication.