From the perspective of information theory and cryptography,the security of two quantum dialogue protocols and a bidirectional quantum secure direct communi-cation(QSDC) protocol was analyzed,and it was pointed out th...From the perspective of information theory and cryptography,the security of two quantum dialogue protocols and a bidirectional quantum secure direct communi-cation(QSDC) protocol was analyzed,and it was pointed out that the transmitted information would be partly leaked out in them.That is,any eavesdropper can elicit some information about the secrets from the public annunciations of the legal us-ers.This phenomenon should have been strictly forbidden in a quantum secure communication.In fact,this problem exists in quite a few recent proposals and,therefore,it deserves more research attention in the following related study.展开更多
This paper studies the security of the block ciphers ARIA and Camellia against impossible differential cryptanalysis. Our work improves the best impossible differential cryptanalysis of ARIA and Camellia known so far....This paper studies the security of the block ciphers ARIA and Camellia against impossible differential cryptanalysis. Our work improves the best impossible differential cryptanalysis of ARIA and Camellia known so far. The designers of ARIA expected no impossible differentials exist for 4-round ARIA. However, we found some nontrivial 4-round impossible differentials, which may lead to a possible attack on 6-round ARIA. Moreover, we found some nontrivial 8-round impossible differentials for Camellia, whereas only 7-round impossible differentials were previously known. By using the 8-round impossible differentials, we presented an attack on 12-round Camellia without FL/FL^-1 layers.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
SMS4 is a 128-bit block cipher used in the WAPI standard for wireless networks in China. In this paper, we analyze the security of the SMS4 block cipher against differential cryptanalysis. Firstly, we prove three theo...SMS4 is a 128-bit block cipher used in the WAPI standard for wireless networks in China. In this paper, we analyze the security of the SMS4 block cipher against differential cryptanalysis. Firstly, we prove three theorems and one corollary that reflect relationships of 5- and 6-round SMS4. Next, by these relationships, we clarify the minimum number of active S-boxes in 6-, 7- and 12-round SMS4 respectively. Finally, based on the above results, we present a family of about 2^14 differential characteristics for 19-round SMS4, which leads to an attack on 23-round SMS4 with 2^118 chosen plaintexts and 2^126.7 encryptions.展开更多
In this papert weights of output set and of input set for finiteautomata are discussed. For a weakly invertible finite automaton, we proye thatfor states with minimal output weight, the distribution of input sets is u...In this papert weights of output set and of input set for finiteautomata are discussed. For a weakly invertible finite automaton, we proye thatfor states with minimal output weight, the distribution of input sets is uniform.Then for a kind of compound finite automata, we give weights of output set and ofinput set explicitly, and a characterization of their input-trees. For finite automatonpublic key cryptosystems, of which automata in public keys belong to such a kind ofcompound finite automata, we evaluate search amounts of exhaust search algorithmsin average case and in worse case for both encryption and signature, and successfulprobabilities of stochastic search algorithms for both encryption and signature. Inaddition, a result on mutual invertibility of finite automata is also given.展开更多
基金the National High Technology Research and Development Program of China(Grant No.2006AA01Z419)the National Natural Science Foundation of China(Grant Nos.90604023 and 60373059)+3 种基金the National Research Foundation for the Doctoral Program of Higher Edu- cation of China(Grant No.20040013007)the National Laboratory for Modern Communications Science Foundation of China(Grant No.9140C1101010601)the Natural Science Foundation of Beijing(Grant No.4072020)the ISN Open Foundation
文摘From the perspective of information theory and cryptography,the security of two quantum dialogue protocols and a bidirectional quantum secure direct communi-cation(QSDC) protocol was analyzed,and it was pointed out that the transmitted information would be partly leaked out in them.That is,any eavesdropper can elicit some information about the secrets from the public annunciations of the legal us-ers.This phenomenon should have been strictly forbidden in a quantum secure communication.In fact,this problem exists in quite a few recent proposals and,therefore,it deserves more research attention in the following related study.
基金This work is supported by the National Natural Science Foundation of China under Grant No.90604036the National Grand Fundamental Research 973 Program of China under Grant No.2004CB318004.
文摘This paper studies the security of the block ciphers ARIA and Camellia against impossible differential cryptanalysis. Our work improves the best impossible differential cryptanalysis of ARIA and Camellia known so far. The designers of ARIA expected no impossible differentials exist for 4-round ARIA. However, we found some nontrivial 4-round impossible differentials, which may lead to a possible attack on 6-round ARIA. Moreover, we found some nontrivial 8-round impossible differentials for Camellia, whereas only 7-round impossible differentials were previously known. By using the 8-round impossible differentials, we presented an attack on 12-round Camellia without FL/FL^-1 layers.
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.
基金supported by the National Natural Science Foundation of China under Grant Nos.60873259 and 60903212the Knowledge Innovation Project of the Chinese Academy of Sciences
文摘SMS4 is a 128-bit block cipher used in the WAPI standard for wireless networks in China. In this paper, we analyze the security of the SMS4 block cipher against differential cryptanalysis. Firstly, we prove three theorems and one corollary that reflect relationships of 5- and 6-round SMS4. Next, by these relationships, we clarify the minimum number of active S-boxes in 6-, 7- and 12-round SMS4 respectively. Finally, based on the above results, we present a family of about 2^14 differential characteristics for 19-round SMS4, which leads to an attack on 23-round SMS4 with 2^118 chosen plaintexts and 2^126.7 encryptions.
文摘In this papert weights of output set and of input set for finiteautomata are discussed. For a weakly invertible finite automaton, we proye thatfor states with minimal output weight, the distribution of input sets is uniform.Then for a kind of compound finite automata, we give weights of output set and ofinput set explicitly, and a characterization of their input-trees. For finite automatonpublic key cryptosystems, of which automata in public keys belong to such a kind ofcompound finite automata, we evaluate search amounts of exhaust search algorithmsin average case and in worse case for both encryption and signature, and successfulprobabilities of stochastic search algorithms for both encryption and signature. Inaddition, a result on mutual invertibility of finite automata is also given.
