The Researches And Applications Of Multiple Impossible Differentials Attack

As one of the most focus of encryption algorithm,block ciphers,the cornerstones of security for application programs,are used for ensuring the data's confidentiality and facticity.As one of the most powerful methods of cryptanalysis,impossible differential attack plays an increasingly significant role in security analysis of block ciphers.In this paper,we study the techniques which can reduce the complexities of impossible differential attack.We study the security of ARIA-192,AES-192,Kiasu-BC,Deoxys-BC-256 against multiple impossible differentials cryptanalysis in the single key attack model.Results achieved are as follows:1.ARIA is the Korean standard block cipher algorithm.This paper studies the security of 7-round ARIA-192 against multiple impossible differentials cryptanalysis.We propose six special 4-round impossible differentials which have the same input difference and different output difference with the maximum number of nonzero common bytes.Based on these differentials,we construct six attack trails including the maximum number of common subkey bytes.Under such circumstances,we utilize "crossed sieving technique" to improve the efficiency of eliminating common subkeys.Furthermore,we also present an efficient algorithm to recover the master key with guess-and-determine technique.Taking advantage of the above advances,both data and time complexities are reduced in this paper,and we have obtained the best result so far for impossible differential cryptanalysis of ARIA-192.2.AES,The Advanced Encryption Standard,is one of the most widely used block cipher,hence its security focused by cryptographers from all over the world.This paper studies the security of 7-round AES-192 against multiple impossible differentials attack.We construct two types of new impossible differentials distinguishers for 4-round AES.Based on them,we propose two impossible differentials attack trails on 7-round AES-192,which use the same chosen plaintexts and ciphertexts structure.Furthermore,our attack uses the key schedule considerations to reduce the subkey bytes,which can reduce the time complexity.Compared with previous impossible differential attacks of AES-192,our attack scenario can greatly reduce the time complexity.3.Kiasu-BC is a tweakable block cipher presented by Jean et al.in AsiaCrypt 2014.The designers claimed that Kiasu-BC is more lightweight and faster than other tweakable block ciphers from AES,and submitted Kiasu-BC to CAESAR authenticated encryption competition in 2014.This paper takes advantage of the idea that non-zero tweak difference may cancel the difference in the attack trails,and presents multiple impossible differentials cryptanalysis on 8-round Kiasu-BC in the single-key model.Utilizing constructed three attack trails,we can repeatedly sieve subkeys,so as to improve the efficiency of sieving subkey.This paper can improve the previous best impossible differential cryptanalysis on the time,data and memory complexities.This has been the best result so far for impossible differential cryptanalysis of Kiasu-BC.4.Deoxys is one of the final candidates of the CAESAR authenticated encryption competition.In this paper,we present the first cryptanalysis of Deoxys in the single-key model.Specifically,we propose a multiple impossible differentials attack of 8-round Deoxys-BC-256,which can reuse the plaintexts to sieve subkeys,so that the sieving efficiency can be improved.Meanwhile,combined various additional techniques,we obtain the best result of Deoxys-BC-256 in the single-key model so far.