FBC is a lightweight block cipher algorithm with a simple structure and is flexible for implementation with hardware and software.It was one of the 10 algorithms that was promoted to the second round of the National Cryptographic Algorithm Design Competition held by the Chinese Cryptographic Association(CACR)in 2018.The block cipher FBC family includes three versions and supports 128-and 256-bit blocks and 128-and 256-bit keys.In this paper,we focus on the 128-bit versions.We develop a new 14-round differential path for FBC128-128 based on the SAT-based automatic search model,with a probability of 2-102.25.Based on this differential path,we perform differential cryptanalysis of 18-round FBC128-128 and 20-round FBC128-256 keys.The differential cryptanalysis of 18-round FBC128-128 costs the time complexity of 2101.5 and memory complexity of 252.For the differential analysis of 20-round FBC128-256,the time and memory complexities are 2184 and 296,respectively.
block cipherdifferential cryptanalysisFBCBoolean satisfiability problem
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