Hash functions
Learning objectives
- understand the subtle security properties of hash functions
- learn the state of the art in cryptanalysis of hash functions and how this affects applications
- understand goals and learn status of the NIST Advanced Hash Function (SHA-3) competition
Overview
In the 1990s, serious weakness were identified by Dobbertin and others in the most widely used hash functions MD4 and MD5. Later on, the US government had to replace its standard hash function SHA by SHA-1. In 2004 and 2005 Wang and others have made a breakthrough in the cryptanalysis of MD4, MD5, SHA and SHA-1. These results are influencing more and more applications: at the end of 2008, researchers have create a forged X.509 certificate for a CA that uses MD5.
The US government has responded to this hash function crisis by publishing in 2007 a call for candidates for SHA-3, a new cryptographic hash family. In October 2008, 64 submission have been received. After two years, five finalists are left.
The decision is expected by mid 2012. This lecture will report on the status of the SHA-3 competition and the lessons learned; it will also discuss its impact on secure applications.