MD 5
- 1. Message Digest5 Prof. Neeraj Bhargava Kapil Chauhan Department of Computer Science School of Engineering & Systems Sciences MDS University, Ajmer
- 2. Introduction Initial checking of integrity – checksums, then CRC These are only good at detecting lost information due to hardware or transmission errors
- 3. Potential Attack A wants to obtain privileges from B A generates two messages with the same hash values A presents an innocent message to B for his digital signature A applies the signature to the other malicious message with the same hash
- 4. MD5 The solution lay in one-way hashing algorithms These should keep two messages from colliding They should also be sufficiently difficult to reverse-engineer
- 5. MD5 MD5 represents the fifth iteration designed by Ronald Rivest (RSA) Others from other authors include Whirlpool and SHA MD5 is open-source and released under the GPL MD5 is optimized for use on 32-bit computers
- 6. MD5 Hashing MD5("The quick brown fox jumps over the lazy dog") = 9e107d9d372bb6826bd81d3542a419d6 MD5("The quick brown fox jumps over the lazy cog") = 1055d3e698d289f2af8663725127bd4b MD5("") = d41d8cd98f00b204e9800998ecf8427e
- 7. Modern Flaws MD5 uses a short 128-bit hash MD5 has become a popular hashing tool through PHP PASSWORD HASHING Rivest says his algorithm was never designed for this usage Long messages that need an integrity check before encryption
- 8. MD5 Flaws Rainbow tables for passwords COLLISIONS!
- 9. MD5 Collisions 2004 Wang et. al delivered an algorithm that could produce collisions in a few hours on an IBM p690 cluster Algorithm was improved by Lenstra et. al in 2005 to a few hours on a single laptop
- 10. Conclusion A digest algorithm does not provide integrity if collisions are so simple to produce SHA or Whirlpool should be considered until a replacement for MD5 can be found