A new impossible differential attack on SAFER ciphers

This paper presents an improved impossible differential cryptanalysis of SAFER ciphers, which uses the miss-in-the-middle technique developed by Biham et al. We analyze 3.75-round SAFER SK-64,1(In this paper, the number in the name of the ciphers indicates the key length).¹ using 2⁴⁵ chosen plaintexts, 2³⁸ bytes memory and 2⁴² half round computations. Furthermore, the new impossible differential attack on 3.75-round SAFER+/128 uses 2⁷⁸ chosen plaintexts, 2⁷⁵ half round computations and 2⁶⁸ bytes memory. And attack on 3.75-round SAFER++/128 uses 2⁷⁸ data, 2⁶⁶ time, and 2⁶² memory.