Attacks on Cryptographic Hashes in Internet Protocols

Recent announcements of better-than-expected collision attacks in popular hash algorithms have caused some people to question whether common Internet protocols need to be changed, and if so, how. This document summarizes the use of hashes in many protocols, discusses how the collision attacks affect and do not affect the protocols, shows how to thwart known attacks on digital certificates, and discusses future directions for protocol designers. This memo provides information for the Internet community.