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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of cryptology 3 (1991), S. 157-172 
    ISSN: 1432-1378
    Keywords: Random number generator ; Perfect generator ; Polynomial generator ; RSA-scheme
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract Let N be a positive integer and let P ε ℤ [x] be a polynomial that is nonlinear on the set ℤ N of integers modulo N. If, by choosing x at random in an initial segment of ℤ N , P(x) (mod N) appears to be uniformly distributed in ℤ N to any polynomial-time observer, then it is possible to construct very efficient pseudorandom number generators that pass any polynomial-time statistical test. We analyse this generator from two points of view. A complexity theoretic analysis relates the perfectness of the generator to the security of the RSA-scheme. A statistical analysis proves that the least-significant bits of P(x) (mod N) are statistically random.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of cryptology 4 (1991), S. 161-174 
    ISSN: 1432-1378
    Keywords: Digital signatures ; Public-key signatures ; Public-key authentication ; ElGamal signatures ; Discrete logarithm one-way function ; Signatures with preprocessing ; Random exponentiated residues
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract We present a new public-key signature scheme and a corresponding authentication scheme that are based on discrete logarithms in a subgroup of units in ℤ p where p is a sufficiently large prime, e.g., p ≥ 2512. A key idea is to use for the base of the discrete logarithm an integer α in ℤ p such that the order of α is a sufficiently large prime q, e.g., q ≥ 2140. In this way we improve the ElGamal signature scheme in the speed of the procedures for the generation and the verification of signatures and also in the bit length of signatures. We present an efficient algorithm that preprocesses the exponentiation of a random residue modulo p.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Theory of computing systems 5 (1971), S. 246-258 
    ISSN: 1433-0490
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract Using the concept of test functions, we develop a general framework within which many recent approaches to the definition of random sequences can be described. Using this concept we give some definitions of random sequences that are narrower than those proposed in the literature. We formulate an objection to some of these concepts of randomness. Using the notion of effective test function, we formulate a thesis on the “true” concept of randomness.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Mathematical programming 66 (1994), S. 181-199 
    ISSN: 1436-4646
    Keywords: Lattice basis reduction ; LLL-reduction ; Korkin—Zolotarev reduction ; Block Korkin—Zolotarev reduction ; Shortest lattice vector problem ; Subset sum problem ; Low density subset sum algorithm ; Knapsack problem ; Stable reduction algorithm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract We report on improved practical algorithms for lattice basis reduction. We propose a practical floating point version of theL 3-algorithm of Lenstra, Lenstra, Lovász (1982). We present a variant of theL 3-algorithm with “deep insertions” and a practical algorithm for block Korkin—Zolotarev reduction, a concept introduced by Schnorr (1987). Empirical tests show that the strongest of these algorithms solves almost all subset sum problems with up to 66 random weights of arbitrary bit length within at most a few hours on a UNISYS 6000/70 or within a couple of minutes on a SPARC1 + computer.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Computing 13 (1974), S. 155-171 
    ISSN: 1436-5057
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung Wir leiten zwei lineare untere Schranken für die Minimalzahl der 2-stelligen Booleschen Operationen her, die notwendig sind, um gewisse Boolesche Funktionen zu berechnen. Eine Schranke hängt von den Primimplikanten der Booleschen Funktion ab. Die andere hängt von der Menge der Unterfunktionen ab. Beide untere Schranken sind in gewissen Fällen exakt.
    Notes: Abstract We establish two linear lower bounds on the minimal number of 2-ary Boolean operations that are necessary to compute certain Boolean functions. The first bound depends on the structure of primimplicants of the Boolean function. The second bound depends on the structure of the set of subfunctions. Both lower bounds yield the exact cost of an optimal computation in certain cases.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Computing 3 (1968), S. 311-317 
    ISSN: 1436-5057
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Summary The context-sensitive languages do not constitute the total class of languages generated by algorithms. Nevertheless various problems (FERMAT) can be embedded in problems of decidability on context-sensitive grammars. The problems here considered are not only of algebraic interest but treat the transformation of languages by homomorphisms and so concern the simplification of language analysing. Unfortunately the questions examined here are undecidable.
    Notes: Zusammenfassung Die kontextsensitiven Sprachen bilden nicht die allgemeinste Klasse algorithmisch erzeugbarer Sprachen. Dennoch lassen sich vielfältige Probleme (FERMAT) in Entscheidbarkeitsfragen über kontextsensitive Sprachen einbetten. Die hier behandelten Probleme sind sowohl von algebraischem Interesse, als auch für die Umformung von Sprachen durch Homomorphismen und damit für die Analyse wichtig. Leider sind alle gestellten Probleme nicht entscheidbar.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Computing 30 (1983), S. 91-110 
    ISSN: 1436-5057
    Keywords: 10A25 ; 68C25 ; Calculation ; factorization of integers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Abstract The analysis of the integer factoring algorithms of Morrison-Brillhart and Schroeppel is based on a hypothesis concerning the number-theoretic function $$\psi (n,\upsilon ):\# \{ x \in [1,n]\left| {(p prim \wedge p\left| x \right.)} \right. \Rightarrow p \leqslant \upsilon \} .$$ This hypothesis is supported by experimented results, which are also given in this paper. Contrary to previous conjectures our analysis shows, that the algorithm of Morrison-Brillhart is faster than the algorithm of Schroeppel both from practical and asymptotical point of view.
    Notes: Zusammenfassung Die Algorithmen von Morrison-Brillhart und Schroeppel sind für große natürliche Zahlen (allgemeiner Gestalt und bezüglich der worst-case-Rechenzeit) die effizientesten aller bis heute bekannten Faktorisierungsalgorithmen. Der vorgelegte Effizienzvergleich basiert auf einer theoretischen Analyse, deren Annahmen experimentell verifiziert wurden. Wegen der übergroßen Rechenzeiten ist nämlich ein experimenteller Vergleich der Laufzeiten beider Algorithmen für Zahlenn〉1050 zur Zeit technisch sehr schwierig. Die der Analyse zugrunde gelegten Annahmen betreffen das Verhalten der zahlentheoretischen Funktion $$\psi (n,\upsilon ):\# \{ x \in [1,n]\left| {(p prim \wedge p\left| x \right.)} \right. \Rightarrow p \leqslant \upsilon \} $$ sowie damit verwandter Funktionen. Entgegen den bisherigen Vermutungen können wir zeigen, daß der Morrison-Brillhart-Algorithmus dem Schroeppel-Algorithmus für Zahlen aller Größenbereiche überlegen ist.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Combinatorica 10 (1990), S. 333-348 
    ISSN: 1439-6912
    Keywords: 11 H 06 ; 11 H 50
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract Letλ i(L), λi(L*) denote the successive minima of a latticeL and its reciprocal latticeL *, and let [b1,..., b n ] be a basis ofL that is reduced in the sense of Korkin and Zolotarev. We prove that and , where andγ j denotes Hermite's constant. As a consequence the inequalities are obtained forn≥7. Given a basisB of a latticeL in ℝ m of rankn andx∃ℝ m , we define polynomial time computable quantitiesλ(B) andΜ(x,B) that are lower bounds for λ1(L) andΜ(x,L), whereΜ(x,L) is the Euclidean distance fromx to the closest vector inL. If in additionB is reciprocal to a Korkin-Zolotarev basis ofL *, then λ1(L)≤γ n * λ(B) and .
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Acta informatica 1 (1972), S. 345-359 
    ISSN: 1432-0525
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Summary We consider the behaviour of finite automata on infinite binary sequences and study the class of random tests which can be carried out by finite automata. We give several equivalent characterizations of those infinite binary sequences which are random relative to finite automata. These characterizations are based on the concepts of selection rules, martingales and invariance properties defined by finite automata.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Acta informatica 7 (1976), S. 95-107 
    ISSN: 1432-0525
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Summary Let L(f) be the network complexity of a Boolean function L(f). For any n-ary Boolean function L(f) let $$TC(f) = min\{ T_p^{\bar A} (n){\text{ (}}\parallel p\parallel + 1gS_p^{\bar A} {\text{(}}n{\text{):}}res_p^{\bar A} {\text{(}}n{\text{) = }}f\} $$ . Hereby p ranges over all relative Turing programs and Ā ranges over all oracles such that given the oracle Ā, the restriction of p to inputs of length n is a program for L(f). ∥p∥ is the number of instructions of p. T p Ā (n) is the time bound and S p Ā of the program p relative to the oracle Ā on inputs of length n. Our main results are (1) L(f) ≦ O(TC(L(f))), (2) TC(f) ≦ O(L(f) 2 2+ɛ) for every ɛ ⋙ O.
    Type of Medium: Electronic Resource
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