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Privacy for Mobile Code
"... : This position paper discusses the problem of evaluating a function on an untrusted host, while maintaining the confidentiality of the function. A new noninteractive protocol designed to evaluate a function on an untrusted host is presented. The protocol prevents the disclosure of the function und ..."
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: This position paper discusses the problem of evaluating a function on an untrusted host, while maintaining the confidentiality of the function. A new noninteractive protocol designed to evaluate a function on an untrusted host is presented. The protocol prevents the disclosure of the function under cryptographic assumptions. Keywords: Mobile code protection, privacy of computations, malicious hosts. 1 Introduction With the advent of new computing paradigms like mobile code and ubiquitous computing, the privacy and integrity of software programs become a major concern beyond classical data security considerations. Running a program in a potentially hostile environment may raise various security requirements, as follows:  a company might need to prevent the disclosure of certain sensitive algorithms implemented in its software products despite extensive code analysis and reverse engineering by potential intruders including its customers;  a mobile software agent acting on behalf...
Cryptology: From Caesar Ciphers to Publickey Cryptosystems
 The College Mathematics Journal, Vol
, 1987
"... He received an M.A. and Ph.D. (in commutative algebra under the direction of David ..."
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He received an M.A. and Ph.D. (in commutative algebra under the direction of David
Density Attack on the Knapsack Cryptosystems with Enumerative Source (Extended Abstract)
, 2003
"... ..."
Mobile Code Protection with Smartcards
"... : This paper addresses mobile code security with respect to potential integrity and privacy violations originating from the runtime environment. The suggested solution requires a trusted hardware with limited capacity like a smartcard and assures the security of a program executed on untrusted runti ..."
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: This paper addresses mobile code security with respect to potential integrity and privacy violations originating from the runtime environment. The suggested solution requires a trusted hardware with limited capacity like a smartcard and assures the security of a program executed on untrusted runtime environments by means of some interactions between the program and the trusted hardware. The security of this scheme is based on an extension of function hiding using error correcting codes. Unlike prior function hiding schemes, the proposed technique allows multistep execution and the delivery of cleartext output at the remote site. Keywords: mobile code security, integrity, privacy, cryptography. 1 Introduction With the advent of new computing paradigms like mobile code and ubiquitous computing, the privacy and integrity of software programs become a major concern beyond classical data security considerations. Running a program in a potentially hostile environment may raise various ...
Lowdensity attack revisited
 Designs, Codes and Cryptography, 43(1):47–59
, 2007
"... The lowdensity attack proposed by Lagarias and Odlyzko is a powerful algorithm against the subset sum problem. The improvement algorithm due to Coster et al. would solve almost all the problems of density < 0.9408... in the asymptotical sense. On the other hand, the subset sum problem itself is kno ..."
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The lowdensity attack proposed by Lagarias and Odlyzko is a powerful algorithm against the subset sum problem. The improvement algorithm due to Coster et al. would solve almost all the problems of density < 0.9408... in the asymptotical sense. On the other hand, the subset sum problem itself is known as an NPhard problem, and a lot of efforts have been paid to establish publickey cryptosystems based on the problem. In these cryptosystems, densities of the subset sum problems should be higher than 0.9408... in order to avoid the lowdensity attack. For example, the ChorRivest cryptosystem adopted subset sum problems with relatively high densities. In this paper, we further improve the lowdensity attack by incorporating an idea that integral lattice points can be covered with polynomially many spheres of shorter radius and of lower dimension. As a result, the success probability of our attack can be higher than that of Coster et al.’s attack for fixed dimensions. The density bound is also improved for fixed dimensions. Moreover, we numerically show that our improved lowdensity attack makes the success probability higher in case of low Hamming weight solution, such as the ChorRivest cryptosystem, if we assume SVP oracle calls.
Molva Mobile Code Protection with Smartcards Proceedings of the ECOOP 2000 workshop on Mobile Object Systems Sophia Antipolis
 Mobile Code Security Proceedings of the ISYPAR 2000 (4ème Ecole d’Informatique des Systèmes Parallèles Répartis
"... Abstract: This paper addresses mobile code security with respect to potential integrity and privacy violations originating from the runtime environment. The suggested solution requires a trusted hardware with limited capacity like a smartcard and assures the security of a program executed on untrust ..."
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Abstract: This paper addresses mobile code security with respect to potential integrity and privacy violations originating from the runtime environment. The suggested solution requires a trusted hardware with limited capacity like a smartcard and assures the security of a program executed on untrusted runtime environments by means of some interactions between the program and the trusted hardware. The security of this scheme is based on an extension of function hiding using error correcting codes. Unlike prior function hiding schemes, the proposed technique allows multistep execution and the delivery of cleartext output at the remote site.
Cryptology
"... Cryptology has advanced tremendously since 1976; this chapter provides a brief overview of the current stateoftheart in the field. Several major themes predominate in the development. One such theme is the careful elaboration of the definition of security for a cryptosystem. A second theme has be ..."
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Cryptology has advanced tremendously since 1976; this chapter provides a brief overview of the current stateoftheart in the field. Several major themes predominate in the development. One such theme is the careful elaboration of the definition of security for a cryptosystem. A second theme has been the search for provably secure cryptosystems, based on plausible assumptions about the difficulty of specific numbertheoretic problems or on the existence of certain kinds of functions (such as oneway functions). A third theme is the invention of many novel and surprising cryptographic capabilities, such as publickey cryptography, digital signatures, secretsharing, oblivious transfers, and zeroknowledge proofs. These themes have been developed and interwoven so that today theorems of breathtaking generality and power assert the existence of cryptographic techniques capable of solving almost any imaginable cryptographic problem.
Breaking Knapsack Cryptosystems by l_infinity norm Enumeration
, 1996
"... At EUROCRYPT '94 G. Orton proposed a public key cryptosystem based on dense compact knapsacks. We present an efficient depth first search enumeration of l 1 norm short lattice vectors based on Hoelder's inequality and apply this algorithm to break Orton's cryptosystem. Keywords: NPhardness, Kn ..."
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At EUROCRYPT '94 G. Orton proposed a public key cryptosystem based on dense compact knapsacks. We present an efficient depth first search enumeration of l 1 norm short lattice vectors based on Hoelder's inequality and apply this algorithm to break Orton's cryptosystem. Keywords: NPhardness, Knapsack problem, Subset sum problem, Breaking knapsack cryptosystems, Shortest lattice vector problem, Lattice basis reduction, Hoelder's inequality. 1 Introduction and Summary A number of cryptosystems have been based on knapsack problems and it was hoped that the NPhardness of the knapsack problem makes it hard to break the corresponding cryptosystem. A knapsack consists of positive integers a 1 ; : : : ; a n ; y. A solution are integers x 1 ; : : : ; x n in some interval [0; 2 s ) that satisfy P n i=1 a i x i = y. If s ? 1 the knapsack is called compact, knapsack problems with s = 1 are subset sum problems. The density of a knapsack is the quotient (n s)/(bitlength of the maximal ...