IACR News item: 30 September 2014
Qingju Wang, Zhiqiang Liu, Kerem Varici, Yu Sasaki, Vincent Rijmen, Yosuke Todo
ePrint ReportIn this paper, we study the security of SIMON32, SIMON48/72 and SIMON48/96 by using integral, zero-correlation linear and impossible differential cryptanalysis.
Firstly, we present a novel experimental approach to construct the best known integral distinguishers of SIMON32. The small block size, 32 bits, of SIMON32 enables us to experimentally find a 15-round integral distinguisher, based on which we present a key recovery attack on 21-round SIMON32, while previous best results published in FSE 2014 only achieved 19 rounds. Actually, our approach provides a very efficient way to elaborate good integral distinguishers of block ciphers with small block size.
Moreover, by applying the divide-and-conquer technique delicately, we attack 20-round SIMON32, 20-round SIMON48/72 and 21-round SIMON48/96 based on 11 and 12-round zero-correlation linear hulls of SIMON32 and SIMON48 respectively. The results for SIMON32 and SIMON48/96 are better than the known results published in FSE 2014.
Finally, we propose impossible differential attacks on 18-round SIMON32, 18-round SIMON48/72 and 19-round SIMON48/96,
which significantly improve the previous impossible differential attacks. Our analysis together with the previous results show that SIMON maintains enough security margin even if
various approaches of cryptanalysis are considered.
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