http://www.rfc-editor.org/rfc/rfc4590.txt
RFC 4590: RADIUS Extension for Digest Authentication, B. Sterman, D. Sadolevsky, D. Schwartz, D. Williams, W. Beck2006-07-01T23:00:00-00:00This document defines an extension to the Remote Authentication Dial-In User Service (RADIUS) protocol to enable support of Digest Authentication, for use with HTTP-style protocols like the Session Initiation Protocol (SIP) and HTTP. [STANDARDS-TRACK]