A Flaw in The Internal State Recovery Attack on ALPHA-MAC.
Shengbao Wu, Mingsheng Wang, Zheng Yuan · 2010
Abstract. An distinguisher was constructed by utilizing a 2-round col-lision differential path of ALPHA-MAC, with about 265:5 chosen mes-sages and 265:5 queries. Then, this distinguisher was used to recover the internal state([1],[2]). However, a flaw is found in the internal state re-covery attack. The complexity of recovering the internal state is up to 281 exhaustive search. And the complexity of the whole attack will be up to 267 chosen messages and 281 exhaustive search. To repair the flaw, a modified 2-round differential path of ALPHA-MAC is present and a new distinguisher based on this path is proposed. Finally, an attack with about 265:5 chosen messages and 265:5 queries is obtained under the new distinguisher. 1