Security of E2 against Truncated Differential Cryptanalysis

Shiho MORIAI  Makoto SUGITA  Masayuki KANDA  

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E84-A   No.1   pp.319-325
Publication Date: 2001/01/01
Online ISSN: 
Print ISSN: 0916-8508
Type of Manuscript: Special Section PAPER (Special Section on Cryptography and Information Security)
E2,  truncated differential cryptanalysis,  search algorithm,  

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This paper evaluates the security of the block cipher E2 against truncated differential cryptanalysis. We show an algorithm to search for effective truncated differentials. The result of the search confirmed that there exist no truncated differentials that lead to possible attacks for E2 with more than 8 rounds. The best attack breaks an 8-round variant of E2 with either IT-Function (the initial transformation) or FT-Function (the final transformation) using 294 chosen plaintexts. We also found the attack which distinguishes a 7-round variant of E2 with IT- and FT-Functions from a random permutation using 291 chosen plaintexts.