Study On Boomerang Cryptanalysis Of Lightweight Block Ciphers

With the fast development of Internet of Things and computer technology, the information security technology has been concerned widely by the society day by day. Cryptography is a project related with information security, which provides the solid theory foundation for the development of information security. Block ciphers are one part of Cryptography, which are also the principal component to protect the information security in the realm of computer science. While with the evolution of the carrier of information, traditional block ciphers cannot satisfy the modern need of hardware because of the huge calculated amount. Lightweight block ciphers arise in order to satisfy the requirement of people. Lightweight block ciphers have cheap computational costs in both hardware and software implementation which are suitable for resource-restricted devices such as RFID tag and so on. At the same time, lightweight block ciphers have the reasonable strength of security. Several lightweight block ciphers have been proposed so far such as PRESENT, DESL, HEIGHT, LBlock, MIBS and so on.Boomerang cryptanalysis and related-key boomerang cryptanalysis are kind of generalized differential cryptanalysis. The principle of boomerang cryptanalysis is to combine two short truncated differential paths to produce a long differential path with high probability. Researchers can analyze security problems on the basis of the long differential path. We concentrate on this principle and analyze lightweight block ciphers in detail in this thsis.In this thesis, we attack the 21-round LBlock with the help of related-key boomerang cryptanalysis. We combine an 8-round LBlock truncated differential path with a 9-round LBlock truncated differential path to produce a 17-round related-key boomerang distinguisher. On the basis of the distinguisher, we extend 4 round in the end of the distinguisher to analyze the 21-round LBlock with the help of key recovery attack. Among all research results, 21 round is the longest for related-key boomerang cryptanalysis on LBlock. At the same time, we can recover the key of 61-bits, and the data complexity is about 502, the time complexity is about 74.192. In this thesis, we also analyze the reduced-round MIBS with the help of boomerang attack. On the basis of 10-round boomerang distinguisher, we extend one round in the beginning of the distinguisher and one round in the end of the distinguisher respectively. We do the key recovery attack on the 12-round MIBS with the data complexity of 622, and the time complexity of 66.542.