Rogue CA Certificate Using PlayStations and MD5 Collisions

Alex Sotirov and Jacob Appelbaum presented "MD5 Considered Harmful Today: Creating a rogue CA Certificate" at the 25th Chaos Communication Congress (or 25C3). Their process, which relied on a cluster of 200 PS3 consoles creates a valid rogue CA certificate that will be accepted by major browsers. The only real fix for this is for browsers to move to SHA-1, which will avoid the known collision errors in MD5. In the short term, this is unlikely to be exploited, but the proof of concept does point to a need to move to a more secure verification method.

ZDNet has more, including details from Sotirov and Appelbaum, as well as a link to their demo site which uses a backdated CA from 2004 to demonstrate the issue.

Hashing: Making it easier for users

Recently, I've been pondering how infrequently most people take advantage of MD5 or SHA-1/256 hashes of software on download pages. Here are two ways to easily use hash checks on a daily basis.

HashTab, which adds a properties tab to files which lists commonly referenced hashes for the file. This is an easy way to verify hashes in Windows for users who don't keep Cygwin handy

DownTheAll!, a popular and useful download plugin for FireFox will also verify MD5, SHA1, SHA256, and other hashes.


Of course, using md5sum on your *nix box is an easy option as well. How do you integrate hash checks for yourself, and how do you get your users to use them?