Efficient Collision Attack Frameworks for RIPEMD-160

  • Fukang Liu
  • Christoph Dobraunig
  • Florian Mendel
  • Takanori Isobe
  • Gaoli WangEmail author
  • Zhenfu CaoEmail author
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 11693)


RIPEMD-160 is an ISO/IEC standard and has been applied to generate the Bitcoin address with SHA-256. Due to the complex dual-stream structure, the first collision attack on reduced RIPEMD-160 presented by Liu, Mendel and Wang at Asiacrypt 2017 only reaches 30 steps, having a time complexity of \(2^{70}\). Apart from that, several semi-free-start collision attacks have been published for reduced RIPEMD-160 with the start-from-the-middle method. Inspired from such start-from-the middle structures, we propose two novel efficient collision attack frameworks for reduced RIPEMD-160 by making full use of the weakness of its message expansion. Those two frameworks are called dense-left-and-sparse-right (DLSR) framework and sparse-left-and-dense-right (SLDR) framework. As it turns out, the DLSR framework is more efficient than SLDR framework since one more step can be fully controlled, though with extra \(2^{32}\) memory complexity. To construct the best differential characteristics for the DLSR framework, we carefully build the linearized part of the characteristics and then solve the corresponding nonlinear part using a guess-and-determine approach. Based on the newly discovered differential characteristics, we provide colliding messages pairs for the first practical collision attacks on 30 and 31 (out of 80) steps of RIPEMD-160 with time complexity \(2^{35.9}\) and \(2^{41.5}\) respectively. In addition, benefiting from the partial calculation, we can attack 33 and 34 (out of 80) steps of RIPEMD-160 with time complexity \(2^{67.1}\) and \(2^{74.3}\) respectively. When applying the SLDR framework to the differential characteristic used in the Asiacrypt 2017 paper, we significantly improve the time complexity by a factor of \(2^{13}\). However, it still cannot compete with the results obtained from the DLSR framework. To the best of our knowledge, these are the best collision attacks on reduced RIPEMD-160 with respect to the number of steps, including the first colliding message pairs for 30 and 31 steps of RIPEMD-160.


Hash function RIPEMD-160 Start-from-the-middle Collision attack Collision 



We thank the anonymous reviewers of CRYPTO 2019 for their insightful comments and suggestions. Fukang Liu and Zhenfu Cao are supported by National Natural Science Foundation of China (Grant No. 61632012, 61672239). In addition, Fukang Liu is also supported by Invitation Programs for Foreigner-based Researchers of the National Institute of Information and Communications Technology (NICT). Takanori Isobe is supported by Grant-in-Aid for Scientific Research (B) (KAKENHI 19H02141) for Japan Society for the Promotion of Science. Gaoli Wang is supported by the National Natural Science Foundation of China (No. 61572125) and National Cryptography Development Fund (No. MMJJ20180201).

Supplementary material


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Copyright information

© International Association for Cryptologic Research 2019

Authors and Affiliations

  1. 1.Shanghai Key Laboratory of Trustworthy ComputingEast China Normal UniversityShanghaiChina
  2. 2.Graz University of TechnologyGrazAustria
  3. 3.Radboud UniversityNijmegenThe Netherlands
  4. 4.Infineon Technologies AGLudwigsburgGermany
  5. 5.National Institute of Information and Communications TechnologyTokyoJapan
  6. 6.University of HyogoKobeJapan

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