In this paper we present generic attacks on the Lai–Massey scheme inspired by Patarin’s attacks on the Feistel scheme. For bijective round functions, the attacking results are better than non-bijective round functions for the 3, 4-round Lai–Massey scheme. Our results show that there are some security differences of these two schemes against known attacks. The generic attacks on the 4-round and 5-round Lai–Massey scheme require more complexity than the 4-round and 5-round Feistel scheme respectively. Through the analysis we believe the Lai–Massey scheme has some advantage than the Feistel scheme within 5 rounds.
['Yiyuan Luo', 'Xuejia Lai', 'Yujie Zhou']
Generic attacks on the Lai–Massey scheme