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Universally Composable Commitments
, 2001
"... We propose a new security measure for commitment protocols, called Universally Composable ..."
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Cited by 140 (8 self)
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We propose a new security measure for commitment protocols, called Universally Composable
Efficient Cryptographic Schemes Provably as Secure as Subset Sum
 Journal of Cryptology
, 1993
"... We show very efficient constructions for a pseudorandom generator and for a universal oneway hash function based on the intractability of the subset sum problem for certain dimensions. (Pseudorandom generators can be used for private key encryption and universal oneway hash functions for sign ..."
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Cited by 78 (8 self)
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We show very efficient constructions for a pseudorandom generator and for a universal oneway hash function based on the intractability of the subset sum problem for certain dimensions. (Pseudorandom generators can be used for private key encryption and universal oneway hash functions for signature schemes). The increase in efficiency in our construction is due to the fact that many bits can be generated/hashed with one application of the assumed oneway function. All our construction can be implemented in NC using an optimal number of processors. Part of this work done while both authors were at UC Berkeley and part when the second author was at the IBM Almaden Research Center. Research supported by NSF grant CCR 88  13632. A preliminary version of this paper appeared in Proc. of the 30th Symp. on Foundations of Computer Science, 1989. 1 Introduction Many cryptosystems are based on the intractability of such number theoretic problems such as factoring and discrete logarit...
Parallel CoinTossing and ConstantRound Secure TwoParty Computation
 Journal of Cryptology
, 2001
"... Abstract. In this paper we show that any twoparty functionality can be securely computed in a constant number of rounds, where security is obtained against malicious adversaries that may arbitrarily deviate from the protocol specification. This is in contrast to Yao’s constantround protocol that e ..."
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Cited by 76 (14 self)
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Abstract. In this paper we show that any twoparty functionality can be securely computed in a constant number of rounds, where security is obtained against malicious adversaries that may arbitrarily deviate from the protocol specification. This is in contrast to Yao’s constantround protocol that ensures security only in the face of semihonest adversaries, and to its malicious adversary version that requires a polynomial number of rounds. In order to obtain our result, we present a constantround protocol for secure cointossing of polynomially many coins (in parallel). We then show how this protocol can be used in conjunction with other existing constructions in order to obtain a constantround protocol for securely computing any twoparty functionality. On the subject of cointossing, we also present a constantround perfect cointossing protocol, where by “perfect ” we mean that the resulting coins are guaranteed to be statistically close to uniform (and not just pseudorandom). 1
SessionKey Generation using Human Passwords Only
, 2001
"... We present sessionkey generation protocols in a model where the legitimate parties share only a humanmemorizable password. The security guarantee holds with respect to probabilistic polynomialtime adversaries that control the communication channel (between the parties), and may omit, insert and ..."
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Cited by 75 (7 self)
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We present sessionkey generation protocols in a model where the legitimate parties share only a humanmemorizable password. The security guarantee holds with respect to probabilistic polynomialtime adversaries that control the communication channel (between the parties), and may omit, insert and modify messages at their choice. Loosely speaking, the effect of such an adversary that attacks an execution of our protocol is comparable to an attack in which an adversary is only allowed to make a constant number of queries of the form “is w the password of Party A”. We stress that the result holds also in case the passwords are selected at random from a small dictionary so that it is feasible (for the adversary) to scan the entire directory. We note that prior to our result, it was not clear whether or not such protocols were attainable without the use of random oracles or additional setup assumptions.
Practical Quantum Oblivious Transfer
, 1992
"... We describe a protocol for quantum oblivious transfer , utilizing faint pulses of polarized light, by which one of two mutually distrustful parties ("Alice") transmits two onebit messages in such a way that the other party ("Bob") can choose which message he gets but cannot obtain information about ..."
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Cited by 73 (12 self)
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We describe a protocol for quantum oblivious transfer , utilizing faint pulses of polarized light, by which one of two mutually distrustful parties ("Alice") transmits two onebit messages in such a way that the other party ("Bob") can choose which message he gets but cannot obtain information about both messages (he will learn his chosen bit's value with exponentially small error probability and may gain at most exponentially little information about the value of the other bit), and Alice will be entirely ignorant of which bit he received. Neither party can cheat (ie deviate from the protocol while appearing to follow it) in such a way as to obtain more information than what is given by the description of the protocol. Our protocol is easy to modify in order to implement the AllorNothing Disclosure of one out of two string messages, and it can be used to implement bit commitment and oblivious circuit evaluation without complexitytheoretic assumptions, in a way that remains secure e...
Practical and ProvablySecure Commitment Schemes from CollisionFree Hashing
 in Advances in Cryptology  CRYPTO96, Lecture Notes in Computer Science 1109
, 1996
"... . We present a very practical stringcommitment scheme which is provably secure based solely on collisionfree hashing. Our scheme enables a computationally bounded party to commit strings to an unbounded one, and is optimal (within a small constant factor) in terms of interaction, communication, a ..."
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Cited by 64 (6 self)
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. We present a very practical stringcommitment scheme which is provably secure based solely on collisionfree hashing. Our scheme enables a computationally bounded party to commit strings to an unbounded one, and is optimal (within a small constant factor) in terms of interaction, communication, and computation. Our result also proves that constant round statistical zeroknowledge arguments and constantround computational zeroknowledge proofs for NP exist based on the existence of collisionfree hash functions. 1 Introduction String commitment is a fundamental primitive for cryptographic protocols. A commitment scheme is an electronic way to temporarily hide a value that cannot be changed. Such a scheme emulates by means of a protocol the following twostage process. In Stage 1 (the Commit stage), a party called the Sender locks a message in a box, and sends the locked box to another party called the receiver. In Stage 2 (the Decommit stage), the Sender provides the Receiver with ...
Efficient and NonInteractive NonMalleable Commitment
, 2001
"... . We present new constructions of nonmalleable commitment schemes, in the public parameter model (where a trusted party makes parameters available to all parties), based on the discrete logarithm or RSA assumptions. The main features of our schemes are: they achieve nearoptimal communication f ..."
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Cited by 57 (7 self)
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. We present new constructions of nonmalleable commitment schemes, in the public parameter model (where a trusted party makes parameters available to all parties), based on the discrete logarithm or RSA assumptions. The main features of our schemes are: they achieve nearoptimal communication for arbitrarilylarge messages and are noninteractive. Previous schemes either required (several rounds of) interaction or focused on achieving nonmalleable commitment based on general assumptions and were thus efficient only when committing to a single bit. Although our main constructions are for the case of perfectlyhiding commitment, we also present a communicationefficient, noninteractive commitment scheme (based on general assumptions) that is perfectly binding. 1
Fair Games Against an AllPowerful Adversary
 AMS DIMACS Series in Discrete Mathematics and Theoretical Computer Science
, 1991
"... Suppose that a weak (polynomial time) device needs to interact over a clear channel with a strong (infinitelypowerful) and untrustworthy adversarial device. Assuming the existence of oneway functions, during this interaction (game) the infinitelypowerful device can encrypt and (computationally) hi ..."
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Cited by 38 (14 self)
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Suppose that a weak (polynomial time) device needs to interact over a clear channel with a strong (infinitelypowerful) and untrustworthy adversarial device. Assuming the existence of oneway functions, during this interaction (game) the infinitelypowerful device can encrypt and (computationally) hide information from the weak device. However, to keep the game fair, the weak player must hide information from the infinitelypowerful player in the informationtheoretic sense. Clearly, encryption in this case is useless, and other means must be used. In this paper, we show that under a general complexity assumption, this task is always possible to achieve. That is, we show that the weak player can play any polynomial length partialinformation game (or secure protocol) with the strong player using any oneway function; we achieve this by implementing oblivious transfer protocol in this model. We also establish related impossibility results concerning oblivious transfer. In the proof of ou...
On SimulationSound Trapdoor Commitments
 In proceedings of EUROCRYPT ’04, LNCS series
, 2003
"... We study the recently introduced notion of a simulationsound trapdoor commitment (SSTC) scheme. In this paper, we present a new, simpler definition for an SSTC scheme that admits more efficient constructions and can be used in a larger set of applications. Specifically, we show how to construct ..."
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Cited by 33 (1 self)
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We study the recently introduced notion of a simulationsound trapdoor commitment (SSTC) scheme. In this paper, we present a new, simpler definition for an SSTC scheme that admits more efficient constructions and can be used in a larger set of applications. Specifically, we show how to construct SSTC schemes from any oneway functions, and how to construct very efficient SSTC schemes based on specific numbertheoretic assumptions. We also show how to construct simulationsound, nonmalleable, and universallycomposable zeroknowledge protocols using SSTC schemes, yielding, for instance, the most efficient universallycomposable zeroknowledge protocols known. Finally, we explore the relation between SSTC schemes and nonmalleable commitment schemes by presenting a sequence of implication and separation results, which in particular imply that SSTC schemes are nonmalleable.
RoundOptimal Secure TwoParty Computation
 In CRYPTO 2004
, 2004
"... We consider the central cryptographic task of secure twoparty computation: two parties wish to compute some function of their private inputs (each receiving possibly di#erent outputs) where security should hold with respect to arbitrarilymalicious behavior of either of the participants. Despit ..."
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Cited by 33 (4 self)
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We consider the central cryptographic task of secure twoparty computation: two parties wish to compute some function of their private inputs (each receiving possibly di#erent outputs) where security should hold with respect to arbitrarilymalicious behavior of either of the participants. Despite extensive research in this area, the exact roundcomplexity of this fundamental problem (i.e., the number of rounds required to compute an arbitrary polytime functionality) was not previously known.