CLEFIA(named after the French word "Clef" meaning "Key") is an efficient,highly secure block cipher proposed by SONY Corporation in the 14 th International Workshop on Fast Software Encryption(FSE-...CLEFIA(named after the French word "Clef" meaning "Key") is an efficient,highly secure block cipher proposed by SONY Corporation in the 14 th International Workshop on Fast Software Encryption(FSE-2007) and many cryptanalyses have been used to analyze it.According to the property of CLEFIA,a new technique Sandwich-Boomerang cryptanalysis is used on it.An 8-round Sandwich-Boomerang distinguisher of CLEFIA is constructed using the best differential characteristic of CLEFIA.And then,based on the distinguisher,an attack against 10-round CLEFIA is proposed.The number of chosen plaintexts required is 2^(119)(or 2^(120)) and the time complexity is 2^(120)(or 2^(121)).Compared with a 7-round impossible Boomerang distinguisher presented by Choy in the 4th International Workshop on Security(IWSEC-2009),the differential characteristics used in the attack are all the best ones,so it is believed that the attack is the best result that the Boomerang attacks can get on CLEFIA at present.展开更多
This paper presents a characteristic more efficient and has better properties than the set method for solving Boolean equations, which is general characteristic set method. In particular, the authors give a disjoint a...This paper presents a characteristic more efficient and has better properties than the set method for solving Boolean equations, which is general characteristic set method. In particular, the authors give a disjoint and monic zero decomposition algorithm for the zero set of a Boolean equation system and an explicit formula for the number of solutions of a Boolean equation system. The authors also prove that a characteristic set can be computed with a polynomial number of multiplications of Boolean polynomials in terms of the number of variables. As experiments, the proposed method is used to solve equations from cryptanalysis of a class of stream ciphers based on nonlinear filter generators. Extensive experiments show that the method is quite effective.展开更多
基金Supported by the National Science Foundation of China(No.60973161)the Doctoral Fund of Ministry of Education of China(No.200806140010)the National High Technology Research and Development Program of China(No.2009AA01Z422)
文摘CLEFIA(named after the French word "Clef" meaning "Key") is an efficient,highly secure block cipher proposed by SONY Corporation in the 14 th International Workshop on Fast Software Encryption(FSE-2007) and many cryptanalyses have been used to analyze it.According to the property of CLEFIA,a new technique Sandwich-Boomerang cryptanalysis is used on it.An 8-round Sandwich-Boomerang distinguisher of CLEFIA is constructed using the best differential characteristic of CLEFIA.And then,based on the distinguisher,an attack against 10-round CLEFIA is proposed.The number of chosen plaintexts required is 2^(119)(or 2^(120)) and the time complexity is 2^(120)(or 2^(121)).Compared with a 7-round impossible Boomerang distinguisher presented by Choy in the 4th International Workshop on Security(IWSEC-2009),the differential characteristics used in the attack are all the best ones,so it is believed that the attack is the best result that the Boomerang attacks can get on CLEFIA at present.
基金This research is partially supported by a National Key Basic Research Project of China under Grant No.2004CB318000.
文摘This paper presents a characteristic more efficient and has better properties than the set method for solving Boolean equations, which is general characteristic set method. In particular, the authors give a disjoint and monic zero decomposition algorithm for the zero set of a Boolean equation system and an explicit formula for the number of solutions of a Boolean equation system. The authors also prove that a characteristic set can be computed with a polynomial number of multiplications of Boolean polynomials in terms of the number of variables. As experiments, the proposed method is used to solve equations from cryptanalysis of a class of stream ciphers based on nonlinear filter generators. Extensive experiments show that the method is quite effective.
