Annual International Conference on the Theory and Applications of Cryptographic Techniques

EUROCRYPT 2005: Advances in Cryptology – EUROCRYPT 2005 pp 19-35

How to Break MD5 and Other Hash Functions

  • Xiaoyun Wang
  • Hongbo Yu
Conference paper

DOI: 10.1007/11426639_2

Volume 3494 of the book series Lecture Notes in Computer Science (LNCS)

Abstract

MD5 is one of the most widely used cryptographic hash functions nowadays. It was designed in 1992 as an improvement of MD4, and its security was widely studied since then by several authors. The best known result so far was a semi free-start collision, in which the initial value of the hash function is replaced by a non-standard value, which is the result of the attack. In this paper we present a new powerful attack on MD5 which allows us to find collisions efficiently. We used this attack to find collisions of MD5 in about 15 minutes up to an hour computation time. The attack is a differential attack, which unlike most differential attacks, does not use the exclusive-or as a measure of difference, but instead uses modular integer subtraction as the measure. We call this kind of differential a modular differential. An application of this attack to MD4 can find a collision in less than a fraction of a second. This attack is also applicable to other hash functions, such as RIPEMD and HAVAL.

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Copyright information

© Springer-Verlag Berlin Heidelberg 2005

Authors and Affiliations

  • Xiaoyun Wang
    • 1
  • Hongbo Yu
    • 1
  1. 1.Shandong UniversityJinanChina