Dependent Key Ranking Algorithm For Side-channel Attack

As the carrier of the cryptographic algorithm,the security of the cryptographic device determines the security of the information system.Side-channel attacks use the side channel information gener-ated during the operation of the cryptographic device to recover the key,side-channel attacks poses a great threat to the security of the cryptographic device.Therefore,how to evaluate the security of cryptographic devices is an urgent problem to be solved.Key rank estimation algorithm and key enumeration algorithm are two post-processing tools of side-channel attack.Key rank estimation algorithm estimates the rank of the correct key according to the result of the side channel attack.Key enumeration algorithm exploits the result of the side channel attack to enumerate key candidate in a non-increasing order of its score.The two algorithms can obtain the computation power required by an attacker to crack the cryptographic device,they can improve the accuracy in the security evaluation of the cryptography implementations.The existing key rank estimation algorithms and key enumeration algorithms only consider the results of the key-recovery attack.The key-difference recovery attack can recover the difference rela-tionship.This work looks at dependent score lists,which correspond to the result of the key-recovery attack and the key-difference recovery attack.The main work of this paper is as follow.First,we propose a new key rank estimation algorithm that can combine the dependent score lists.We use the XOR relation between the key byte recovery attack and the key-difference recovery attack result to combine these score lists,which is the ranking basis of key rank estimation algorithm.The simulation experiments show that when the number of power traces is enough to obtain reliable results,merging more score lists leads to the rise of the correct key's rank up to 2²⁰,which improves the accuracy of safety assessmentSecond,we study the realization principle of the optimal key enumeration algorithm based on the independent score lists,and extend its design idea the key enumeration algorithm of dependent score lists.We propose an efficient strict key enumeration algorithm that can run recursively for dependent score lists.With simulated side-channel leakage of AES-128,the proposed KE algorithm can enumerate the key according to 16 score lists of subkeys and 15 score lists of sub-key difference.This KE algorithm can enumerate up to 2²¹keys using 5 hours and 128MB of RAM with a normal PC.By taking advantage of the dependent score lists,the key recovery experiments using simulated power data show that the success rate is largely improved in general.