Practical-time Attack on the Full MMB Block Cipher

Modular Multiplication based Block Cipher (MMB) is a block cipher designed by Daemen et al. as an alternative to the IDEA block cipher. In this paper, we give a practical-time attack on the full MMB with adaptive chosen plaintexts and ciphertexts. By the constructive sandwich distinguisher for 5 of the 6 rounds of MMB with amazingly high probability 1, we give the key recovery attack on the full MMB with data complexity 2 and time complexity 2 MMB encryptions. Then a rectangle-like sandwich attack on the full MMB is presented, with 2 chosen plaintexts, 2 MMB encryptions and 2 memory bytes. By the way, we show an improved differential attack on the full MMB with data complexity of 2 chosen plaintexts and ciphertexts, time complexity 2 encryptions and 2 bytes of memory.