Results 1  10
of
26
Adaptively Secure Multiparty Computation
, 1996
"... A fundamental problem in designing secure multiparty protocols is how to deal with adaptive adversaries (i.e., adversaries that may choose the corrupted parties during the course of the computation), in a setting where the channels are insecure and secure communication is achieved by cryptographi ..."
Abstract

Cited by 77 (8 self)
 Add to MetaCart
A fundamental problem in designing secure multiparty protocols is how to deal with adaptive adversaries (i.e., adversaries that may choose the corrupted parties during the course of the computation), in a setting where the channels are insecure and secure communication is achieved by cryptographic primitives based on the computational limitations of the adversary.
Studies in Secure Multiparty Computation and Applications
, 1996
"... Consider a set of parties who do not trust each other, nor the channels by which they communicate. Still, the parties wish to correctly compute some common function of their local inputs, while keeping their local data as private as possible. This, in a nutshell, is the problem of secure multiparty ..."
Abstract

Cited by 77 (8 self)
 Add to MetaCart
Consider a set of parties who do not trust each other, nor the channels by which they communicate. Still, the parties wish to correctly compute some common function of their local inputs, while keeping their local data as private as possible. This, in a nutshell, is the problem of secure multiparty computation. This problem is fundamental in cryptography and in the study of distributed computations. It takes many different forms, depending on the underlying network, on the function to be computed, and on the amount of distrust the parties have in each other and in the network. We study several aspects of secure multiparty computation. We first present new definitions of this problem in various settings. Our definitions draw from previous ideas and formalizations, and incorporate aspects that were previously overlooked. Next we study the problem of dealing with adaptive adversaries. (Adaptive adversaries are adversaries that corrupt parties during the course of the computation, based on...
AccountableSubgroup Multisignatures
 In Proceedings of CCS 2001
, 2000
"... Formal models and security proofs are especially important for multisignatures: in contrast to threshold signatures, no precise definitions were ever provided for such schemes, and some proposals were subsequently broken. ..."
Abstract

Cited by 43 (2 self)
 Add to MetaCart
Formal models and security proofs are especially important for multisignatures: in contrast to threshold signatures, no precise definitions were ever provided for such schemes, and some proposals were subsequently broken.
Synthesizers and Their Application to the Parallel Construction of PseudoRandom Functions
, 1995
"... A pseudorandom function is a fundamental cryptographic primitive that is essential for encryption, identification and authentication. We present a new cryptographic primitive called pseudorandom synthesizer and show how to use it in order to get a parallel construction of a pseudorandom function. ..."
Abstract

Cited by 42 (10 self)
 Add to MetaCart
A pseudorandom function is a fundamental cryptographic primitive that is essential for encryption, identification and authentication. We present a new cryptographic primitive called pseudorandom synthesizer and show how to use it in order to get a parallel construction of a pseudorandom function. We show several NC¹ implementations of synthesizers based on concrete intractability assumptions as factoring and the DiffieHellman assumption. This yields the first parallel pseudorandom functions (based on standard intractability assumptions) and the only alternative to the original construction of Goldreich, Goldwasser and Micali. In addition, we show parallel constructions of synthesizers based on other primitives such as weak pseudorandom functions or trapdoor oneway permutations. The security of all our constructions is similar to the security of the underlying assumptions. The connection with problems in Computational Learning Theory is discussed.
The (True) Complexity of Statistical Zero Knowledge (Extended Abstract)
 Proceedings of the 22nd Annual ACM Symposium on the Theory of Computing, ACM
, 1990
"... ) Mihir Bellare Silvio Micali y Rafail Ostrovsky z MIT Laboratory for Computer Science 545 Technology Square Cambridge, MA 02139 Abstract Statistical zeroknowledge is a very strong privacy constraint which is not dependent on computational limitations. In this paper we show that given a comp ..."
Abstract

Cited by 40 (17 self)
 Add to MetaCart
) Mihir Bellare Silvio Micali y Rafail Ostrovsky z MIT Laboratory for Computer Science 545 Technology Square Cambridge, MA 02139 Abstract Statistical zeroknowledge is a very strong privacy constraint which is not dependent on computational limitations. In this paper we show that given a complexity assumption a much weaker condition suffices to attain statistical zeroknowledge. As a result we are able to simplify statistical zeroknowledge and to better characterize, on many counts, the class of languages that possess statistical zeroknowledge proofs. 1 Introduction An interactive proof involves two parties, a prover and a verifier, who talk back and forth. The prover, who is computationally unbounded, tries to convince the probabilistic polynomial time verifier that a given theorem is true. A zeroknowledge proof is an interactive proof with an additional privacy constraint: the verifier does not learn why the theorem is true [11]. That is, whatever the polynomialtime verif...
Practical ZeroKnowledge Proofs: Giving Hints and Using Deficiencies
 JOURNAL OF CRYPTOLOGY
, 1994
"... New zeroknowledge proofs are given for some numbertheoretic problems. All of the problems are in NP, but the proofs given here are much more efficient than the previously known proofs. In addition, these proofs do not require the prover to be superpolynomial in power. A probabilistic polynomial t ..."
Abstract

Cited by 32 (0 self)
 Add to MetaCart
New zeroknowledge proofs are given for some numbertheoretic problems. All of the problems are in NP, but the proofs given here are much more efficient than the previously known proofs. In addition, these proofs do not require the prover to be superpolynomial in power. A probabilistic polynomial time prover with the appropriate trapdoor knowledge is sufficient. The proofs are perfect or statistical zeroknowledge in all cases except one.
Open Problems in Number Theoretic Complexity, II
"... this paper contains a list of 36 open problems in numbertheoretic complexity. We expect that none of these problems are easy; we are sure that many of them are hard. This list of problems reflects our own interests and should not be viewed as definitive. As the field changes and becomes deeper, new ..."
Abstract

Cited by 26 (0 self)
 Add to MetaCart
this paper contains a list of 36 open problems in numbertheoretic complexity. We expect that none of these problems are easy; we are sure that many of them are hard. This list of problems reflects our own interests and should not be viewed as definitive. As the field changes and becomes deeper, new problems will emerge and old problems will lose favor. Ideally there will be other `open problems' papers in future ANTS proceedings to help guide the field. It is likely that some of the problems presented here will remain open for the forseeable future. However, it is possible in some cases to make progress by solving subproblems, or by establishing reductions between problems, or by settling problems under the assumption of one or more well known hypotheses (e.g. the various extended Riemann hypotheses, NP 6= P; NP 6= coNP). For the sake of clarity we have often chosen to state a specific version of a problem rather than a general one. For example, questions about the integers modulo a prime often have natural generalizations to arbitrary finite fields, to arbitrary cyclic groups, or to problems with a composite modulus. Questions about the integers often have natural generalizations to the ring of integers in an algebraic number field, and questions about elliptic curves often generalize to arbitrary curves or abelian varieties. The problems presented here arose from many different places and times. To those whose research has generated these problems or has contributed to our present understanding of them but to whom inadequate acknowledgement is given here, we apologize. Our list of open problems is derived from an earlier `open problems' paper we wrote in 1986 [AM86]. When we wrote the first version of this paper, we feared that the problems presented were so difficult...
Improved noncommitting encryption schemes based on a general complexity assumption
 In CRYPTO'00, SpringerVerlag (LNCS 1880
, 2000
"... Abstract. Noncommitting encryption enables the construction of multiparty computation protocols secure against an adaptive adversary in the computational setting where private channels between players are not assumed. While any noncommitting encryption scheme must be secure in the ordinary semanti ..."
Abstract

Cited by 24 (2 self)
 Add to MetaCart
Abstract. Noncommitting encryption enables the construction of multiparty computation protocols secure against an adaptive adversary in the computational setting where private channels between players are not assumed. While any noncommitting encryption scheme must be secure in the ordinary semantic sense, the converse is not necessarily true. We propose a construction of noncommitting encryption that can be based on any publickey system which is secure in the ordinary sense and which has an extra property we call simulatability. This generalises an earlier scheme proposed by Beaver based on the DiffieHellman problem, and we propose another implementation based on RSA. In a more general setting, our construction can be based on any collection of trapdoor permutations with a certain simulatability property. This offers a considerable efficiency improvement over the first noncommitting encryption scheme proposed by Canetti et al. Finally, at some loss of efficiency, our scheme can be based on general collections of trapdoor permutations without the simulatability assumption, and without the commondomain assumption of Canetti et al. In showing this last result, we identify and correct a bug in a key generation protocol from Canetti et al. 1
Asymptotic semismoothness probabilities
 Mathematics of computation
, 1996
"... Abstract. We call an integer semismooth with respect to y and z if each of its prime factors is ≤ y, and all but one are ≤ z. Such numbers are useful in various factoring algorithms, including the quadratic sieve. Let G(α, β)bethe asymptotic probability that a random integer n is semismooth with res ..."
Abstract

Cited by 22 (1 self)
 Add to MetaCart
Abstract. We call an integer semismooth with respect to y and z if each of its prime factors is ≤ y, and all but one are ≤ z. Such numbers are useful in various factoring algorithms, including the quadratic sieve. Let G(α, β)bethe asymptotic probability that a random integer n is semismooth with respect to n β and n α. We present new recurrence relations for G and related functions. We then give numerical methods for computing G,tablesofG, and estimates for the error incurred by this asymptotic approximation. 1.
The Dark Side of "BlackBox" Cryptography or: Should We Trust Capstone?
 in Advances in Cryptology  Crypto '96
, 1996
"... . The use of cryptographic devices as "black boxes", namely trusting their internal designs, has been suggested and in fact Capstone technology is offered as a next generation hardwareprotected escrow encryption technology. Software cryptographic servers and programs are being offered as well, for ..."
Abstract

Cited by 21 (4 self)
 Add to MetaCart
. The use of cryptographic devices as "black boxes", namely trusting their internal designs, has been suggested and in fact Capstone technology is offered as a next generation hardwareprotected escrow encryption technology. Software cryptographic servers and programs are being offered as well, for use as library functions, as cryptography gets more and more prevalent in computing environments. The question we address in this paper is how the usage of cryptography as a black box exposes users to various threats and attacks that are undetectable in a blackbox environment. We present the SETUP (Secretly Embedded Trapdoor with Universal Protection) mechanism, which can be embedded in a cryptographic blackbox device. It enables an attacker (the manufacturer) to get the user's secret (from some stage of the output process of the device) in an unnoticeable fashion, yet protects against attacks by others and against reverse engineering (thus, maintaining the relative advantage of the actual...