Algebraic techniques in differential cryptanalysis revisited

  • Authors:
  • Meiqin Wang;Yue Sun;Nicky Mouha;Bart Preneel

  • Affiliations:
  • School of Mathematics, Shandong University, Jinan, China and Department of Electrical Engineering, ESAT, SCD-COSIC, Katholieke Universiteit Leuven, Heverlee, Belgium and Interdisciplinary Institut ...;School of Mathematics, Shandong University, Jinan, China;Department of Electrical Engineering, ESAT, SCD-COSIC, Katholieke Universiteit Leuven, Heverlee, Belgium and Interdisciplinary Institute for BroadBand Technology, Belgium;Department of Electrical Engineering, ESAT, SCD-COSIC, Katholieke Universiteit Leuven, Heverlee, Belgium and Interdisciplinary Institute for BroadBand Technology, Belgium

  • Venue:
  • ACISP'11 Proceedings of the 16th Australasian conference on Information security and privacy
  • Year:
  • 2011

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Abstract

At FSE 2009, Albrecht et al. proposed a new cryptanalytic method that combines algebraic and differential cryptanalysis. They introduced three new attacks, namely Attack A, Attack B and Attack C. For Attack A, they explain that the time complexity is difficult to determine. The goal of Attacks B and C is to filter out wrong pairs and then recover the key. In this paper, we show that Attack C does not provide an advantage over differential cryptanalysis for typical block ciphers, because it cannot be used to filter out any wrong pairs that satisfy the ciphertext differences. Furthermore, we explain why Attack B provides no advantage over differential cryptanalysis for PRESENT. We verify our results for PRESENT experimentally, using both PolyBoRi and MiniSat. Our work helps to understand which equations are important in the differential-algebraic attack. Based on our findings, we present two new differential-algebraic attacks. Using the first method, our attack on 15-round PRESENT-80 requires 259 chosen plaintexts and has a worstcase time complexity of 273.79 equivalent encryptions. Our new attack on 14-round PRESENT-128 requires 255 chosen plaintexts and has a worstcase time complexity of 2112.83 equivalent encryptions. Although these attacks have a higher time complexity than the differential attacks, their data complexity is lower.