Title: Improved Truncated Differential Attacks on SAFER
Abstract: Knudsen and Berson have applied truncated differential attack on 5 round SAFER K-64 successfully. However, their attack is not efficient when applied on 5 round SAFER SK-64 (with the modified key schedule) and can not be applied on 6 round SAFER. In this paper, we improve the truncated differential attack on SAFER by using better truncated differential and additional filtering method. Our attack on 5 round SAFER (both SAFER K-64 and SAFER SK-64) can find the secret key much faster than by exhaustive search. Also, the number of chosen plaintexts required are less than those needed in Knudsen and Berson’s attack. Our attack on 6 round SAFER (both SAFER K-64 and SAFER SK-64) can find the secret key faster than by exhaustive search.