In this paper, the mutual information between clock-controlled input and output sequences is discussed. It is proved that the mutual information is a strictly monotone increasing function of the length of output seque...In this paper, the mutual information between clock-controlled input and output sequences is discussed. It is proved that the mutual information is a strictly monotone increasing function of the length of output sequence, and its divergent rate is gaven.展开更多
This paper proposes an efficient, high-tech method of construction of pseudorandom binary sequences generators with a repetition period 2n?for n-bit shift register with a nonlinear feedback function. The developed met...This paper proposes an efficient, high-tech method of construction of pseudorandom binary sequences generators with a repetition period 2n?for n-bit shift register with a nonlinear feedback function. The developed method is illustrated by constructing a nonlinear function feedback shift register. It is proved that the offered method requires the realization of a memory size proportional to n2?that allows making successful use of suitable generators for practical use on the shift register of the longer word.展开更多
Suppose that x={x（n）}<sub>n∈Z</sub> is a sequence of real numbers. For each p∈N, x<sup>（p）</sup>={x<sup>（p）</sup>（n）}<sub>n∈Z</sub> is the resulting sequence ...Suppose that x={x（n）}<sub>n∈Z</sub> is a sequence of real numbers. For each p∈N, x<sup>（p）</sup>={x<sup>（p）</sup>（n）}<sub>n∈Z</sub> is the resulting sequence of x through p times median filterings with window 2k+1. It is proved that when p→∞, both x<sup>（2p）</sup> and x<sup>（2p-1）</sup> are convergent. Thus the problem of convergence of the median filters of infinite-length sequences is completely solved.展开更多
In this paper,we continuously discuss the statistical properties of non-linear feedforward sequences of m-sequences We give the number of 0-runs and 1-runs in some cases.
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In this paper, the mutual information between clock-controlled input and output sequences is discussed. It is proved that the mutual information is a strictly monotone increasing function of the length of output sequence, and its divergent rate is gaven.
文摘This paper proposes an efficient, high-tech method of construction of pseudorandom binary sequences generators with a repetition period 2n?for n-bit shift register with a nonlinear feedback function. The developed method is illustrated by constructing a nonlinear function feedback shift register. It is proved that the offered method requires the realization of a memory size proportional to n2?that allows making successful use of suitable generators for practical use on the shift register of the longer word.
基金Project supported by the National Natural Science Foundation of China (Grant No. 16971047)
文摘Suppose that x={x（n）}<sub>n∈Z</sub> is a sequence of real numbers. For each p∈N, x<sup>（p）</sup>={x<sup>（p）</sup>（n）}<sub>n∈Z</sub> is the resulting sequence of x through p times median filterings with window 2k+1. It is proved that when p→∞, both x<sup>（2p）</sup> and x<sup>（2p-1）</sup> are convergent. Thus the problem of convergence of the median filters of infinite-length sequences is completely solved.
文摘In this paper,we continuously discuss the statistical properties of non-linear feedforward sequences of m-sequences We give the number of 0-runs and 1-runs in some cases.
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.
