The k-error linear complexity is an important cryptographic measure of pseudorandom sequences in stream ciphers. In this paper, we investigate the k-error linear complexity of p2-periodic binary sequences defined from...
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The k-error linear complexity is an important cryptographic measure of pseudorandom sequences in stream ciphers. In this paper, we investigate the k-error linear complexity of p2-periodic binary sequences defined from the polynomial quotients modulo p, which are the generalizations of the well-studied Fermat ***, first we determine exact values of the k-error linear complexity over the finite field F2 for these binary sequences under the assumption of 2 being a primitive root modulo p2, and then we determine their k-error linear complexity over the finite field Fp. Theoretical results obtained indicate that such sequences possess‘good’ errorlinearcomplexity.
The d-ary Sidel'nikov sequence S = s(0), s(1).. of period q - 1 for a prime power q = p(m) is a frequently analyzed sequence in the literature. Recently, it turned out that the linearcomplexity over F-p of the (d...
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The d-ary Sidel'nikov sequence S = s(0), s(1).. of period q - 1 for a prime power q = p(m) is a frequently analyzed sequence in the literature. Recently, it turned out that the linearcomplexity over F-p of the (d-ary Sidel'nikov sequence is considerably smaller than the period if the sequence element S (q - 1) /2mod (q - 1) is chosen adequately. In this paper this work is continued and tight lower bounds on the linearcomplexity over F, of the d-ary Sidel'nikov sequence are given. For certain cases exact values are provided. Finally, results on the k-error linear complexity over Fp of the d-ary Sidel'nikov sequence are presented.
In his 1986 book, Rueppel conjectured that periodic binary sequences have expected linearcomplexity close to the period length N. In this paper, we determine the expected value of the linearcomplexity of N-periodic ...
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In his 1986 book, Rueppel conjectured that periodic binary sequences have expected linearcomplexity close to the period length N. In this paper, we determine the expected value of the linearcomplexity of N-periodic sequences explicitly and confirm Rueppel's conjecture for arbitrary finite fields. Cryptographically strong sequences should not only have a large linearcomplexity, but also the change of a few terms should not cause a significant decrease of the linearcomplexity. This requirement leads to the concept of the k-error linear complexity of N-periodic sequences. We present a method to establish a lower bound on the expected k-error linear complexity of N-periodic sequences based on the knowledge of the counting function V-N,V- 0 (c), i.e., the number of N-periodic sequences with given linearcomplexity c. For some cases, we give explicit formulas for that lower bound and we also determine N-N,N- 0 (c).
The linear Games-Chan algorithm for computing the linearcomplexity c(s) of a binary sequence s of period l = 2(n) requires the knowledge of the full sequence, while the quadratic Berlekamp-Massey algorithm requires k...
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The linear Games-Chan algorithm for computing the linearcomplexity c(s) of a binary sequence s of period l = 2(n) requires the knowledge of the full sequence, while the quadratic Berlekamp-Massey algorithm requires knowledge of only 2c(s) terms. We show that we can modify the Games-Chan algorithm so that it computes the complexity in linear time knowing only 2c(s) terms. The algorithms of Stamp-Martin and Lauder-Paterson can also be modified, without loss of efficiency, to compute analogs of the k-error linear complexity for finite binary sequences viewed as initial segments of infinite sequences with period a power of two. We also develop an algorithm which, given a constant c and an infinite binary sequence s with period l = 2(n), computes the minimum number k of errors (and an associated error sequence) needed over a period of s for bringing the linearcomplexity of s below c. The algorithm has a time and space bit complexity of O(l). We apply our algorithm to decoding and encoding binary repeated-root cyclic codes of length l in linear, O(t), time and space. A previous decoding algorithm proposed by Lauder and Paterson has O(l(logl)(2)) complexity.
In this correspondence, we study the statistical stability properties of p(m)-periodic binary sequences in terms of their linearcomplexity and k-error linear complexity, where 1) is a prime number and 2 is a primitiv...
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In this correspondence, we study the statistical stability properties of p(m)-periodic binary sequences in terms of their linearcomplexity and k-error linear complexity, where 1) is a prime number and 2 is a primitive root modulo p(2). We show that their linearcomplexity and k-error linear complexity take a value only from some specific ranges. We then present the minimum value k for which the k-error linear complexity is strictly less than the linearcomplexity in a new viewpoint different from the approach by Meidl. We also derive the distribution of p(m)-periodic binary sequences with specific k-error linear complexity. Finally, we get an explicit formula for the expectation value of the k-error linear complexity and give its lower and upper bounds, when k <= [p/2].
The linearcomplexity and the k-error linear complexity are important concepts for the theory of stream ciphers in cryptology. keystreams that are suitable for stream ciphers must have large values of these complexity...
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The linearcomplexity and the k-error linear complexity are important concepts for the theory of stream ciphers in cryptology. keystreams that are suitable for stream ciphers must have large values of these complexity measures. We study periodic sequences over an arbitrary finite field F-q and establish conditions under which there are many periodic sequences over linearcomplexity N, and k-error linear complexity close to N. The existence of many such sequences thwarts attacks against the keystreams by exhaustive search.
The k-error linear complexity of a sequence is a fundamental concept for assessing the stability of the linearcomplexity. After computing the k-error linear complexity of a sequence, those bits that cause the linear ...
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The k-error linear complexity of a sequence is a fundamental concept for assessing the stability of the linearcomplexity. After computing the k-error linear complexity of a sequence, those bits that cause the linearcomplexity reduced also need to be determined. For binary sequences with period 2p(n), where p is an odd prime and 2 is a primitive root modulo p(2), we present an algorithm which computes the minimum number k such that the k-error linear complexity is not greater than a given constant c. The corresponding error sequence is also obtained.
Niederreiter showed that there is a class of periodic sequences which possess large linearcomplexity and large k-error linear complexity simultaneously. This result disproved the conjecture that there exists a trade-...
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Niederreiter showed that there is a class of periodic sequences which possess large linearcomplexity and large k-error linear complexity simultaneously. This result disproved the conjecture that there exists a trade-off between the linearcomplexity and the k-error linear complexity of a periodic sequence by Ding et al. By considering the orders of the divisors of x(N)-1 over F-q, we obtain three main results which hold for much larger k than those of Niederreiter et al.: a) sequences with maximal linearcomplexity and almost maximal k-error linear complexity with general periods;b) sequences with maximal linearcomplexity and maximal k-error linear complexity with special periods;c) sequences with maximal linearcomplexity and almost maximal k-error linear complexity in the asymptotic case with composite periods. Besides, we also construct some periodic sequences with low correlation and large k-error linear complexity.
An algorithm is given for the k-error linear complexity of sequences over GF(p(m)) with period p(n), p a prime. The algorithm is derived by the generalized Games-Chan algorithm for the linearcomplexity of sequences o...
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An algorithm is given for the k-error linear complexity of sequences over GF(p(m)) with period p(n), p a prime. The algorithm is derived by the generalized Games-Chan algorithm for the linearcomplexity of sequences over GF(p(m)) with period p(n) and by using the modified cost different from that used in the Stamp-Martin algorithm for sequences over GF(2) with period 2(n). A method is also given for computing an error vector which gives the k-error linear complexity. (C) 1999 Academic Press.
This paper studies the stability of the linearcomplexity of l-sequences. Let (s) under bar be an I-sequence with linearcomplexity attaining the maximum per((s) under bar)/2 + 1. A tight lower bound and an upper boun...
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This paper studies the stability of the linearcomplexity of l-sequences. Let (s) under bar be an I-sequence with linearcomplexity attaining the maximum per((s) under bar)/2 + 1. A tight lower bound and an upper bound on minerror((s) under bar), i.e., the minimal value k for which the k-error linear complexity of (s) under bar is strictly less than its linearcomplexity, are given. In particular, for an I-sequence (s) under bar based on a prime number of the form 2r + 1, where r is an odd prime number with primitive root 2, it is shown that minerror((s) under bar) is very close to r, which implies that this kind of I-sequences have very stable linearcomplexity. (C) 2010 Published by Elsevier Inc.
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