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18
A tale of two sieves
 Notices Amer. Math. Soc
, 1996
"... It is the best of times for the game of factoring large numbers into their prime factors. In 1970 it was barely possible to factor “hard ” 20digit numbers. In 1980, in the heyday of the BrillhartMorrison continued fraction factoring algorithm, factoring of 50digit numbers was becoming commonplace ..."
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Cited by 42 (2 self)
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It is the best of times for the game of factoring large numbers into their prime factors. In 1970 it was barely possible to factor “hard ” 20digit numbers. In 1980, in the heyday of the BrillhartMorrison continued fraction factoring algorithm, factoring of 50digit numbers was becoming commonplace. In 1990 my own quadratic sieve factoring algorithm had doubled the length of the numbers that could be factored, the record having 116 digits. By 1994 the quadratic sieve had factored the famous 129digit RSA challenge number that had been estimated in Martin Gardner’s 1976 Scientific American column to be safe for 40 quadrillion years (though other estimates around then were more modest). But the quadratic sieve is no longer the champion. It was replaced by Pollard’s number field sieve in the spring of 1996, when that method successfully split a 130digit RSA challenge number in about 15 % of the time the quadratic sieve would have taken. In this article we shall briefly meet these factorization algorithms—these two sieves—and some of the many people who helped to develop them. In the middle part of this century, computational issues seemed to be out of fashion. In most books the problem of factoring big numbers
Unconditional Sender and Recipient Untraceability in spite of Active Attacks
, 1989
"... . A protocol is described which allows to send and receive messages anonymously using an arbitrary communication network, and it is proved to be unconditionally secure. This improves a result by DAVID CHAUM: The DCnet guarantees the same, but on the assumption of a reliable broadcast network. Since ..."
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Cited by 42 (1 self)
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. A protocol is described which allows to send and receive messages anonymously using an arbitrary communication network, and it is proved to be unconditionally secure. This improves a result by DAVID CHAUM: The DCnet guarantees the same, but on the assumption of a reliable broadcast network. Since unconditionally secure Byzantine Agreement cannot be achieved, such a reliable broadcast network cannot be realized by algorithmic means. The solution proposed here, the DC + net, uses the DCnet, but replaces the reliable broadcast network by a failstop one. By choosing the keys necessary for the DCnet dependently on the previously broadcast messages, the failstop broadcast can be achieved unconditionally secure and without increasing the complexity of the DCnet significantly, using an arbitrary communication network. Categories and Subject Descriptors: C.2.0 [ComputerCommunication Networks]: General  Security and protection, E.3 [Data Encryption], F.2.1 [Analysis of Algorithms...
Discrete Logarithms: the Effectiveness of the Index Calculus Method
, 1996
"... . In this article we survey recent developments concerning the discrete logarithm problem. Both theoretical and practical results are discussed. We emphasize the case of finite fields, and in particular, recent modifications of the index calculus method, including the number field sieve and the func ..."
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Cited by 26 (1 self)
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. In this article we survey recent developments concerning the discrete logarithm problem. Both theoretical and practical results are discussed. We emphasize the case of finite fields, and in particular, recent modifications of the index calculus method, including the number field sieve and the function field sieve. We also provide a sketch of the some of the cryptographic schemes whose security depends on the intractibility of the discrete logarithm problem. 1 Introduction Let G be a cyclic group generated by an element t. The discrete logarithm problem in G is to compute for any b 2 G the least nonnegative integer e such that t e = b. In this case, we write log t b = e. Our purpose, in this paper, is to survey recent work on the discrete logarithm problem. Our approach is twofold. On the one hand, we consider the problem from a purely theoretical perspective. Indeed, the algorithms that have been developed to solve it not only explore the fundamental nature of one of the basic s...
Recent progress and prospects for integer factorisation algorithms
 In Proc. of COCOON 2000
, 2000
"... Abstract. The integer factorisation and discrete logarithm problems are of practical importance because of the widespread use of public key cryptosystems whose security depends on the presumed difficulty of solving these problems. This paper considers primarily the integer factorisation problem. In ..."
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Cited by 21 (1 self)
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Abstract. The integer factorisation and discrete logarithm problems are of practical importance because of the widespread use of public key cryptosystems whose security depends on the presumed difficulty of solving these problems. This paper considers primarily the integer factorisation problem. In recent years the limits of the best integer factorisation algorithms have been extended greatly, due in part to Moore’s law and in part to algorithmic improvements. It is now routine to factor 100decimal digit numbers, and feasible to factor numbers of 155 decimal digits (512 bits). We outline several integer factorisation algorithms, consider their suitability for implementation on parallel machines, and give examples of their current capabilities. In particular, we consider the problem of parallel solution of the large, sparse linear systems which arise with the MPQS and NFS methods. 1
Building Cyclic Elliptic Curves Modulo Large Primes
 Advances in Cryptology  EUROCRYPT '91, Lecture Notes in Computer Science
, 1987
"... Elliptic curves play an important role in many areas of modern cryptology such as integer factorization and primality proving. Moreover, they can be used in cryptosystems based on discrete logarithms for building oneway permutations. For the latter purpose, it is required to have cyclic elliptic cu ..."
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Cited by 19 (2 self)
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Elliptic curves play an important role in many areas of modern cryptology such as integer factorization and primality proving. Moreover, they can be used in cryptosystems based on discrete logarithms for building oneway permutations. For the latter purpose, it is required to have cyclic elliptic curves over finite fields. The aim of this note is to explain how to construct such curves over a finite field of large prime cardinality, using the ECPP primality proving test of Atkin and Morain. 1 Introduction Elliptic curves prove to be a powerful tool in modern cryptology. Following the original work of H. W. Lenstra, Jr. [18] concerning integer factorization, many researchers have used this new idea to work out primality proving algorithms [8, 14, 2, 4, 22] as well as cryptosystems [21, 16] generalizing those of [12, 1, 9]. Recent work on these topics can be found in [20, 19]. More recently, Kaliski [15] has used elliptic curves in the design of oneway permutations. For this, the autho...
A Public Key Cryptosystem based on Block Upper Triangular Matrices
 WSEAS Information Security and Privacy (2005) 163168 WSEAS TRANSACTIONS on MATHEMATICS Rafael Alvarez, FranciscoMiguel Martinez, JoseFrancisco Vicent, and Antonio Zamora ISSN: 11092769 Issue 4, Volume 7
, 2008
"... Abstract: We propose a public key cryptosystem based on block upper triangular matrices. This system is a variant of the Discrete Logarithm Problem with elements in a finite group, capable of increasing the difficulty of the problem while maintaining the key size. We also propose a key exchange pro ..."
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Abstract: We propose a public key cryptosystem based on block upper triangular matrices. This system is a variant of the Discrete Logarithm Problem with elements in a finite group, capable of increasing the difficulty of the problem while maintaining the key size. We also propose a key exchange protocol that guarantees that both parties share a secret element of this group and a digital signature scheme that provides data authenticity and integrity.
A New Public Key Cryptosystem based on Matrices
 WSEAS Information Security and Privacy
, 2007
"... This work was partially supported by the Spanish grants GV06/018 Abstract: This paper describes a new method for authentication and integrity where the ciphertext is obtained using block upper triangular matrices with elements in pZ, in which the discrete logarithm problem (DLP) defined over a fini ..."
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This work was partially supported by the Spanish grants GV06/018 Abstract: This paper describes a new method for authentication and integrity where the ciphertext is obtained using block upper triangular matrices with elements in pZ, in which the discrete logarithm problem (DLP) defined over a finite group is used. In the proposed public key cryptosystem, the encryption requires very few operations and decryption is equivalent to the DLP and, finally, the signature scheme presented is based on the ElGamal signature scheme and requires the original message in order to verify the signature. With this system we get a large key space without increasing the difficulty of the problem.
Efficient Primitives from Exponentiation in Z_p
, 2006
"... Since DiffieHellman [14], many secure systems, based on discrete logarithm or DiffieHellman assumption in Z_p, were introduced in the literature. In this work, we investigate the possibility to construct efficient primitives from exponentiation techniques over Z_p. Consequently, we propose a new p ..."
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Since DiffieHellman [14], many secure systems, based on discrete logarithm or DiffieHellman assumption in Z_p, were introduced in the literature. In this work, we investigate the possibility to construct efficient primitives from exponentiation techniques over Z_p. Consequently, we propose a new pseudorandom generator, where its security is proven under the decisional DiffieHellman assumption. Our generator is the most efficient among all generators from Z*_p that are provably secure under standard assumptions. If an appropriate precomputation is allowed, our generator can produce O(log log p) bits per modular multiplication. This is the best possible result in...
A Matricial Public Key Cryptosystem with
 Digital Signature  WSEAS TRANSACTIONS on MATHEMATICS Manuscript received Nov. 28, 2007; revised
, 2008
"... Abstract: We describe a new public key cryptosystem using block upper triangular matrices with elements in pZ, based on a generalization of the discrete logarithm problem over a finite group. The proposed cryptosystem is very efficient, requiring very few operations and also allows an ElGamal based ..."
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Abstract: We describe a new public key cryptosystem using block upper triangular matrices with elements in pZ, based on a generalization of the discrete logarithm problem over a finite group. The proposed cryptosystem is very efficient, requiring very few operations and also allows an ElGamal based digital signature scheme. The main benefit is that the security level is higher than other algorithms for the same key size.
Computational Methods in Public Key Cryptology
, 2002
"... These notes informally review the most common methods from computational number theory that have applications in public key cryptology. ..."
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These notes informally review the most common methods from computational number theory that have applications in public key cryptology.