Abstract:

The related key rectangle-like sandwich attack is used to improve cryptanalysis on 44-round SHACAL-2. With the combination of modular difference and XOR difference and  substituting a single difference with more differences, the probability of the differential path is improved and a 35-round related key rectangle-like sandwich distinguisher with probability 2^-430 is given. Applying the distinguisher, the key recovery attack on 44-round SHACAL-2 with related keys is introduced, with 2²¹⁷ chosen plaintexts, 2^476.92 44-round encryptions and 2²²² bytes of memory.

Key words: SHACAL-2; related key; rectangle-like sandwich distinguisher; modular difference