This paper discusses pseudo-randomness of a periodic sequence, named the fourth class of GSS sequence. We get the following results: ① Its least period always reaches the maximum (that is, 2n-1). ② Its least period ...This paper discusses pseudo-randomness of a periodic sequence, named the fourth class of GSS sequence. We get the following results: ① Its least period always reaches the maximum (that is, 2n-1). ② Its least period and linear complexity keep robust under single-symbol-substitution. ③ It has good low-degree-auto-correlation feature. ④ It has good short-length-run-distribution.展开更多
Periodic sequences over finite fields, constructed by classical cyclotomic classes and generalized cyclotomic classes, have good pseudorandom properties. The linear complexity of a period sequence plays a fundamental ...Periodic sequences over finite fields, constructed by classical cyclotomic classes and generalized cyclotomic classes, have good pseudorandom properties. The linear complexity of a period sequence plays a fundamental role in the randomness of sequences. Let p, q, and r be distinct odd primes with gcd（p-1, q-1 ）=gcd（p- 1, r-1）=gcd（q-1, r-1）=2. In this paper, a new class of generalized cyclotomic sequence with respect to pqr over GF（2） is constructed by finding a special characteristic set. In addition, we determine its linear complexity using cyclotomic theory. Our results show that these sequences have high linear complexity, which means they can resist linear attacks.展开更多
In this paper, we analyze the security of a new stream cipher-COSvd（2,128）. This cipher was proposed by E. Filiol et al. at the ECRYPT SASC＇2004 （The State of the Art of Stream Ciphers）. It uses clock-controlled ...In this paper, we analyze the security of a new stream cipher-COSvd（2,128）. This cipher was proposed by E. Filiol et al. at the ECRYPT SASC＇2004 （The State of the Art of Stream Ciphers）. It uses clock-controlled non-linear feedback registers together with an S-box controlled by a chaotic sequence and was claimed to prevent any existing attacks. However, our analysis shows that there are some serious security flaws in the design of the S-box, resulting in heavy biased byte distribution in the keystream. In some broadcast applications, this flaw will cause a ciphertext-only attack with high success rate. Besides, there are also many security flaws in other parts of the cipher. We point out these flaws one by one and develop a divide-and-conquer attack to recover the secret keys from O（2^26）-byte known plaintext with success rate 93.4597% and complexity O（2^113）, which is much lower than 2^512, the complexity of exhaustive search.展开更多
文摘This paper discusses pseudo-randomness of a periodic sequence, named the fourth class of GSS sequence. We get the following results: ① Its least period always reaches the maximum (that is, 2n-1). ② Its least period and linear complexity keep robust under single-symbol-substitution. ③ It has good low-degree-auto-correlation feature. ④ It has good short-length-run-distribution.
基金supported by the National Natural Science Foundation of China (Nos.61272492,61103231,61202492,61202395,61462077,and 61562077)the Program for New Century Excellent Talents in University (No.NCET-12-0620)
文摘Periodic sequences over finite fields, constructed by classical cyclotomic classes and generalized cyclotomic classes, have good pseudorandom properties. The linear complexity of a period sequence plays a fundamental role in the randomness of sequences. Let p, q, and r be distinct odd primes with gcd（p-1, q-1 ）=gcd（p- 1, r-1）=gcd（q-1, r-1）=2. In this paper, a new class of generalized cyclotomic sequence with respect to pqr over GF（2） is constructed by finding a special characteristic set. In addition, we determine its linear complexity using cyclotomic theory. Our results show that these sequences have high linear complexity, which means they can resist linear attacks.
基金supported by the National Natural Science Foundation of China(Grant Nos.60273027,60373047)the National Grand Fundamental Research 973 Program of China(Grant No.2004CB318004).
文摘In this paper, we analyze the security of a new stream cipher-COSvd（2,128）. This cipher was proposed by E. Filiol et al. at the ECRYPT SASC＇2004 （The State of the Art of Stream Ciphers）. It uses clock-controlled non-linear feedback registers together with an S-box controlled by a chaotic sequence and was claimed to prevent any existing attacks. However, our analysis shows that there are some serious security flaws in the design of the S-box, resulting in heavy biased byte distribution in the keystream. In some broadcast applications, this flaw will cause a ciphertext-only attack with high success rate. Besides, there are also many security flaws in other parts of the cipher. We point out these flaws one by one and develop a divide-and-conquer attack to recover the secret keys from O（2^26）-byte known plaintext with success rate 93.4597% and complexity O（2^113）, which is much lower than 2^512, the complexity of exhaustive search.
