Boomerang Analysis Method Research On The Block Cipher

With the rapid development of e-commerce and e-government, more and more like apersonal bank account information requires strict confidentiality, so how to ensure theinformation safety is particularly important. As one of the core technology of informationsecurity, cryptography has a vital fundamental role. The block cipher is an important technologyto guarantee information confidentiality and integrity ,and it has been widely used in the field ofinformation security.Cryptanalysis, is also called cryptology attack technique, which is in the case of withoutknowing the key, according information of the ciphertext to recover the plaintext or key, and canalso find the weakness of the cryptosystem. Important purpose of a block cipher cryptanalysis isto use a smaller time complexity and storage complexity to analyze as much as possible thenumber of rounds. Boomerang attack technique of modern block cipher proposed is just order toattack the algorithm more round. After the launch of the Boomerang attack methods, scholars athome and abroad use it to analyze many algorithms’ security, and achieved certain results. Inorder to make it analyze block cipher more useful, we make up our mind to make contributionsto the study of the Boomerang analysis method. In this paper, we make use of the Boomerangmethod to analyze the Data Encryption Standard (DES) in the U.S. last century and ThreeFish ofSkein algorithm’s core component, and Skein designed based on block cipher and finalistsSHA-3 program .The research results are as follows:1.Because of Boomerang method is proposed on the basis of the differential analysismethod, we first use a combination of differential analysis and related key analysis to achievesuccessfully the attack of the 5 round DES. According to DES key schedule characteristics andbased on the order of each subkey and absent bit, we properly set plaintext difference and keydifference, and obtains 5-rounds differential path. Depending on the differential path, select 3pairs plaintexts and ciphertexts,we can get 44-bit subkey in fifth round with differential analysismethod, then by exhaustive search to determine the remaining 12 bits.2.based on the 5 round DES related key differential analysis and Boomerang attack method,we gets 9-rounds DES related key Boomerang attack. Firstly, construct a DES eight roundsdistinguish, then, plus one round after this eight distinguish. And attack the 9 rounds DES by theBoomerang analyze methods. The time complexity of the attack about 231encryption anddecryption operations, data complexity is 240.3.In order to further study the Boomerang attack method of block cipher, Based on theThreeFish-256 key schedule algorithm features, and select the appropriate related key. by theBoomerang attack methods,we get more round Boomerang attack distinguisher, ie 32 rounddistinguisher.