Known-Key Attacks on Type-2 GFN with SPS Round Function

Tianli WANG
Jiao DU
Shanqi PANG

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E99-A    No.7    pp.1488-1493
Publication Date: 2016/07/01
Online ISSN: 1745-1337
DOI: 10.1587/transfun.E99.A.1488
Type of Manuscript: LETTER
Category: Cryptography and Information Security
type-2 GFN,  SPS round function,  rebound attack,  known-key distinguisher,  near-collision,  

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We present a rebound attack on the 4-branch type-2 generalized Feistel structure with an SPS round function, which is called the type-2 GFN-SPS in this paper. Applying a non-full-active-match technique, we construct a 6-round known-key truncated differential distinguisher, and it can deduce a near-collision attack on compression functions of this structure embedding the MMO or MP modes. Extending the 6-round attack, we build a 7-round truncated differential path to get a known-key differential distinguisher with seven rounds. The results give some evidences that this structure is not stronger than the type-2 GFN with an SP round function and not weaker than that with an SPSP round function against the rebound attack.