http://www.rfc-editor.org/rfc/rfc4109.txt
RFC 4109: Algorithms for Internet Key Exchange version 1 (IKEv1), P. Hoffman2005-05-01T23:00:00-00:00The required and suggested algorithms in the original Internet Key Exchange version 1 (IKEv1) specification do not reflect the current reality of the IPsec market requirements. The original specification allows weak security and suggests algorithms that are thinly implemented. This document updates RFC 2409, the original specification, and is intended for all IKEv1 implementations deployed today. [STANDARDS-TRACK]