http://www.nullsoft.com/free/waste/security.html - Security section
http://www.nullsoft.com/free/waste/network.html - Network design
http://slashdot.org/article.pl?sid=03/05/29/0140241&mode=thread&tid=126&tid=93 - Slashdot discusssion
Nullsoft, who did Winamp and Gnutella, just released a package called W A S T E which does encrypted communications within small groups of people. It doesn't appear to have had outside analysis of its security yet, but they do invite it, and they say it needs some work.
