Automatic Search for Key-Bridging Technique: Applications to LBlock and TWINE
Key schedules in block ciphers are often highly simplified, which causes weakness that can be exploited in many attacks.At ASIACRYPT 2011, Dunkelman et al.proposed a technique using the weakness in the key schedule of AES, called key-bridging technique, to improve the overall complexity.The advantage of key-bridging technique is that it allows the adversary to deduce some sub-key bits from some other sub-key bits, even though they are separated by many key mixing steps.Although the relations of successive rounds may be easy to see, the relations of two rounds separated by some mixing steps are very hard to find.In this paper, we describe a versatile and powerful algorithm for searching key-bridging technique on word-oriented and bit-oriented block ciphers.To demonstrate the usefulness of our approach, we apply our tool to the impossible differential and multidimensional zero correlation linear attacks on 23-round LBlock, 23-round TWINE-80 and 25-round TWINE-128.To the best of our knowledge, these results are the currently best results on LBlock and TWINE in the single-key setting.
Block Ciphers Key-Bridging Technique Automatic Search Impossible Differential Cryptanalysis Zero-Correlation Linear Cryptanalysis LBlock TWINE
Li Lin Wenling Wu Yafei Zheng
TCA Laboratory, SKLCS, Institute of Software, Chinese Academy of Sciences, Beijing, China State Key Laboratory of Cryptology, P.O.Box 5159, Beijing 100878, China Graduate University of Chinese Academy of Sciences, Beijing 100190, China
国内会议
成都
英文
27-46
2016-07-01（万方平台首次上网日期，不代表论文的发表时间）