Automatic Tools Based Security Analysis On Cryptographic Algorithms

Automatic search is one of the important methods in modern cryptanalysis.At present,the commonly used automatic search tools include Satisfiability modulo theo-ry(SMT)solver and Mixed-Integer Linear Programming(MILP)search tool.We make a differential cryptanalysis on SipHash and LEA by SMT-technique,and we make a RX-cryptanalysis on SipHash by it.And we make a internal cryptanalysis on LiCi by com-bining MILP with division property.The results are as follows:(1)By combining SMT technique with differential cryptanalysis,for the case of SipHash-2-x with one message block,we find a colliding characteristic with probability 2-241,this result better than the colliding characteristic with probability 2-242*is got by Dobraunig in SAC 2014.For LEA,we construct an 11-round differential characteristic with probability 2-92,and construct a 12-round differential charac-teristic with probability 2-107,and construct a 13-round differential characteristic with probability 2-127,they are the best results in published differential character-istic of LEA.(2)By combining SMT technique with RX-cryptanalysis,for the case of SipHash-l-x with one message block,we find an RX-colliding characteristic with probability 2-93.6,enriching the analysis results of the SipHash.(3)By combining MILP with bit-based division property,we construct a 12-round in-tegral distinguisher,and then we make a 13-round key recovery attack on LiCi,the data complexity is 263,and the time complexity is 241,this is the best integral result so far.