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数理解析研究所講究録

Symmetricity of the Protocols Related to Oblivious Transfer (Foundations of Theoretical Computer Science : For New Computational View)

Daisuke Inoue, Keisuke Tanaka

Published May 1, 2008• 0 citations
OpenAlex

Abstract

In this paper, we show that the special case of strong conditional oblivious transfer from $S$ to $R$ can be obtained from only one instance of itself from $R$ to $S$ .Our reduction protocol Is simple and efficient, and preserves the security of the inversion.

Related papers

Symmetricity of the Protocols Related to Oblivious Transfer

Daisuke INOUE, Keisuke Tanaka

In this paper, we show that each of the special cases of strong conditional oblivious transfer can be obtained from only one instance of its inverse. Each of our constructions is simple and efficient, and preserves the same security level of its inverse.

IEICE Transactions on Fundamentals of Electronics Communications and Computer Sciences•Jan 1, 2009•0 citations

Oblivious-Transfer Amplification

Jürg Wullschleger

Oblivious transfer is a primitive of paramount importance in cryptography or, more precisely, two- and multi-party computation due to its universality. Unfortunately, oblivious transfer cannot be achieved in an unconditionally secure way for both parties from scratch. Therefore, it is a natural question what information-theoretic primitives or computational assumptions oblivious transfer can be based on. The results in our thesis are threefold. First, we present a protocol that implements oblivious transfer from a weakened oblivious transfer called universal oblivious transfer, where one of the two players may get additional information. Our reduction is about twice as efficient as previous results. Weak oblivious transfer is an even weaker form of oblivious transfer, where both players may obtain additional information about the other player's input, and where the output can contain errors. We give a new, weaker definition of weak oblivious transfer, as well as new reductions with a more detailed analysis. Finally, we carry over our results to the computational setting and show how a weak oblivious transfer that is sometimes incorrect and only mildly secure against computationally bounded adversaries can be strengthened.

arXiv:cs/0608076•Aug 18, 2006•5 citations

A general model for oblivious transfer

Hossein Ghodosi

Naor and Pinkas (1999a) pointed out that 'this is of interest, given the possibility of implementing Oblivious Transfer using physical means, e.g., via a noisy channel or quantum cryptography. However, some of these reductions are not particularly efficient. .. '. Using tamper-proof smart cards, we propose some radically different approaches to the Oblivious Transfer problem. Despite the simplicity of our model, we achieve unconditional security and privacy for both the sender and receiver. In contrast to all known oblivious transfer protocols, which require extensive computations, the proposed schemes are very computationally efficient.

•Jan 1, 2007•3 citations

Efficient computational oblivious transfer using interactive hashing

Kirill Morozov, George Savvides

We present two protocols for reducing oblivious transfer (OT) to the security of trapdoor permutations and to the hardness of some coding problems, respectively. The first protocol is the most efficient known to date, while the second one is a theoretical proof-of-concept. Our constructions leverage the power of Interactive Hashing (IH). The first protocol can be viewed as a simple modification of the well-known OT construction by Even, Goldreich and Lem-pel (1985), in which a receiver must send a random domain element to a sender through IH. Alternatively, our protocol can be viewed as a simple modification of the construction by Ostrovsky, Venkatesan and Yung (1993), in which the players substitute the one-way permutation with a trapdoor permutation. We use a similar approach to derive a second OT protocol based on coding assumptions related to security of the McEliece cryptosystem. In our second construction, the receiver inputs a public key into IH while privately keeping the corresponding secret key. Two different versions of IH are used: the computationally secure one in the first protocol, and the information-theoretically secure one in the second.

ACM Asia Conference on Computer and Communications Security (ASIA CCS)•Mar 22, 2011•1 citation

Oblivious Transfer Is Symmetric.

Stefan Wolf, Jürg Wullschleger

Abstract. We show that oblivious transfer of bits from A to B can be obtained from a single instance of the same primitive from B to A. Our reduction is perfect and shows that oblivious transfer is in fact a symmetric functionality. This solves an open problem posed by Crépeau and Sántha in 1991. 1

•Jan 1, 2004•15 citations

Strong Conditional Oblivious Transfer and Computing on Intervals

Ian F. Blake, Vladimir Kolesnikov

Abstract. We consider the problem of securely computing the Greater Than (GT) predicate and its generalization – securely determining membership in a union of intervals. We approach these problems from the point of view of Q-Conditional Oblivious Transfer (Q-COT), introduced by Di Crescenzo, Ostrovsky and Rajagopalan [4]. Q-COT is an oblivious transfer that occurs iff predicate Q evaluates to true on the parties’ inputs. We are working in the semi-honest model with computationally unbounded receiver. In this paper, we propose: (i) a stronger, simple and intuitive definition of COT, which we call strong COT, or Q-SCOT. (ii) A simpler and more efficient one-round protocol for securely computing GT and GT-SCOT. (iii) A simple and efficient modular construction reducing SCOT based on membership in a union of intervals (UI-SCOT) to GT-SCOT, producing an efficient one-round UI-SCOT. 1

•Jan 1, 2004•0 citations
In this paper, we show that the special case of strong conditional oblivious transfer from SSS to RRR can be obtained from only one instance of itself from RRR to SSS .Our reduction protocol Is simple and efficient, and preserves the security of the inversion.
Oblivious transfer is a primitive of paramount importance in cryptography or, more precisely, two- and multi-party computation due to its universality. Unfortunately, oblivious transfer cannot be achieved in an unconditionally secure way for both parties from scratch. Therefore, it is a natural question what information-theoretic primitives or computational assumptions oblivious transfer can be based on. The results in our thesis are threefold. First, we present a protocol that implements oblivious transfer from a weakened oblivious transfer called universal oblivious transfer, where one of the two players may get additional information. Our reduction is about twice as efficient as previous results. Weak oblivious transfer is an even weaker form of oblivious transfer, where both players may obtain additional information about the other player's input, and where the output can contain errors. We give a new, weaker definition of weak oblivious transfer, as well as new reductions with a more detailed analysis. Finally, we carry over our results to the computational setting and show how a weak oblivious transfer that is sometimes incorrect and only mildly secure against computationally bounded adversaries can be strengthened.
Naor and Pinkas (1999a) pointed out that 'this is of interest, given the possibility of implementing Oblivious Transfer using physical means, e.g., via a noisy channel or quantum cryptography. However, some of these reductions are not particularly efficient. .. '. Using tamper-proof smart cards, we propose some radically different approaches to the Oblivious Transfer problem. Despite the simplicity of our model, we achieve unconditional security and privacy for both the sender and receiver. In contrast to all known oblivious transfer protocols, which require extensive computations, the proposed schemes are very computationally efficient.
We present two protocols for reducing oblivious transfer (OT) to the security of trapdoor permutations and to the hardness of some coding problems, respectively. The first protocol is the most efficient known to date, while the second one is a theoretical proof-of-concept. Our constructions leverage the power of Interactive Hashing (IH). The first protocol can be viewed as a simple modification of the well-known OT construction by Even, Goldreich and Lem-pel (1985), in which a receiver must send a random domain element to a sender through IH. Alternatively, our protocol can be viewed as a simple modification of the construction by Ostrovsky, Venkatesan and Yung (1993), in which the players substitute the one-way permutation with a trapdoor permutation. We use a similar approach to derive a second OT protocol based on coding assumptions related to security of the McEliece cryptosystem. In our second construction, the receiver inputs a public key into IH while privately keeping the corresponding secret key. Two different versions of IH are used: the computationally secure one in the first protocol, and the information-theoretically secure one in the second.
Abstract. We consider the problem of securely computing the Greater Than (GT) predicate and its generalization – securely determining membership in a union of intervals. We approach these problems from the point of view of Q-Conditional Oblivious Transfer (Q-COT), introduced by Di Crescenzo, Ostrovsky and Rajagopalan [4]. Q-COT is an oblivious transfer that occurs iff predicate Q evaluates to true on the parties’ inputs. We are working in the semi-honest model with computationally unbounded receiver. In this paper, we propose: (i) a stronger, simple and intuitive definition of COT, which we call strong COT, or Q-SCOT. (ii) A simpler and more efficient one-round protocol for securely computing GT and GT-SCOT. (iii) A simple and efficient modular construction reducing SCOT based on membership in a union of intervals (UI-SCOT) to GT-SCOT, producing an efficient one-round UI-SCOT. 1