Comprehensive Study of Integral Analysis on LBlock

Yu SASAKI  Lei WANG  

Publication
IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E97-A   No.1   pp.127-138
Publication Date: 2014/01/01
Online ISSN: 1745-1337
Print ISSN: 0916-8508
Type of Manuscript: Special Section PAPER (Special Section on Cryptography and Information Security)
Category: Symmetric Key Based Cryptography
Keyword: 
LBlock,  integral analysis,  partial-sum,  meet-in-the-middle,  subkey relations,  

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Summary: 
The current paper presents an integral cryptanalysis in the single-key setting against light-weight block-cipher LBlock reduced to 22 rounds. Our attack uses the same 15-round integral distinguisher as the previous attacks, but many techniques are taken into consideration in order to achieve comprehensive understanding of the attack; choosing the best balanced-byte position, meet-in-the-middle technique to identify right key candidates, partial-sum technique, relations among subkeys, and combination of the exhaustive search with the integral analysis. Our results indicate that the integral cryptanalysis is particularly useful for LBlock like structures. At the end of this paper, which factor makes the LBlock structure weak against the integral cryptanalysis is discussed. Because designing light-weight cryptographic primitives is an actively discussed topic, we believe that this paper returns some useful feedback to future designs.