A Practical Related-Key Boomerang Attack for the Full MMB Block Cipher

摘要

The MMB block cipher (Modular Multiplication-based Block cipher) is an iterative block cipher designed by Daemen, Govaerts, and Vandewalle in 1993 as an improvement of the PES and IPES ciphers. In this paper we present several new related-key differential characteristics of MMB. These characteristics can be used to form several related-key boomerangs to attack the full MMB. Using 2~(20) adaptive chosen plaintexts and ciphertexts we recover all key bits in 2~(35.2) time for the full MMB. Our attack was experimentally verified, and it takes less than 15 minutes on a standard Intel i5 machine to recover the full MMB key. After showing this practical attack on the full key of the full MMB, we present attacks on extended versions of MMB with up to 8 rounds (which is two more rounds than in the full MMB). We recover 64 out of the 128 key in time of 2~(32.2) for 7-round MMB, and time of 2~(32) for 8-round MMB using 2~(20) plaintexts.