Fast Software Encryption

Volume 4047 of the series Lecture Notes in Computer Science pp 262-277

A Study of the MD5 Attacks: Insights and Improvements

  • John BlackAffiliated withUniversity of Colorado at Boulder
  • , Martin CochranAffiliated withUniversity of Colorado at Boulder
  • , Trevor HighlandAffiliated withUniversity of Texas at Austin


MD5 is a well-known and widely-used cryptographic hash function. It has received renewed attention from researchers subsequent to the recent announcement of collisions found by Wang et al. [16]. To date, however, the method used by researchers in this work has been fairly difficult to grasp.

In this paper we conduct a study of all attacks on MD5 starting from Wang. We explain the techniques used by her team, give insights on how to improve these techniques, and use these insights to produce an even faster attack on MD5. Additionally, we provide an “MD5 Toolkit” implementing these improvements that we hope will serve as an open-source platform for further research.

Our hope is that a better understanding of these attacks will lead to a better understanding of our current collection of hash functions, what their strengths and weaknesses are, and where we should direct future efforts in order to produce even stronger primitives.


Cryptographic Hash Functions Differential Cryptanalysis MD5