http://www.rfc-editor.org/rfc/rfc2403.txt
RFC 2403: The Use of HMAC-MD5-96 within ESP and AH, C. Madson, R. Glenn1998-11-01T23:00:00-00:00This memo describes the use of the HMAC algorithm in conjunction with the MD5 algorithm as an authentication mechanism within the revised IPSEC Encapsulating Security Payload and the revised IPSEC Authentication Header. [STANDARDS-TRACK]