aqora

Oblivious and fair server-aided two-party computation

Amir Herzberg, Haya Shulman

Information Security Technical ReportApr 10, 201310 citations

Impossibility of composable Oblivious Transfer in relativistic quantum cryptography

Lorenzo Laneve, Lídia del Rio

We study the cryptographic primitive Oblivious Transfer; a composable construction of this resource would allow arbitrary multi-party computation to be carried out in a secure way, i.e. to compute functions in a distributed way while keeping inputs from different parties private. First we review a framework that allows us to analyze composability of classical and quantum cryptographic protocols in special relativity: Abstract Cryptography implemented with Causal Boxes. We then (1) explore and formalize different versions of oblivious transfer found in the literature, (2) prove that their equivalence holds also in relativistic quantum settings, (3) show that it is impossible to composably construct any of these versions of oblivious transfer from only classical or quantum communication among distrusting agents in relativistic settings, (4) prove that the impossibility also extends to multi-party computation, and (5) provide a mutual construction between oblivious transfer and bit commitment.We study the cryptographic primitive Oblivious Transfer; a composable construction of this resource would allow arbitrary multi-party computation to be carried out in a secure way, i.e. to compute functions in a distributed way while keeping inputs from different parties private. First we review a framework that allows us to analyze composability of classical and quantum cryptographic protocols in special relativity: Abstract Cryptography implemented with Causal Boxes. We then (1) explore and formalize different versions of oblivious transfer found in the literature, (2) prove that their equivalence holds also in relativistic quantum settings, (3) show that it is impossible to composably construct any of these versions of oblivious transfer from only classical or quantum communication among distrusting agents in relativistic settings, (4) prove that the impossibility also extends to multi-party computation, and (5) provide a mutual construction between oblivious transfer and bit commitment.

arXiv:2106.11200Jun 21, 20213 citations

Distributed Oblivious Transfer

Moni Naor, Benny Pinkas B

Lecture notes in computer scienceJan 1, 2000105 citations

An efficient PMPC protocol

Jianhua Ge

The private multi-party computation protocol proposed by Claude Crepeau etc.is not only complicated but very inefficient.This paper describes a new protocol with an efficient global commitment transfer sub-protocol.With a first two round string oblivious transfer,the protocol can avoid performing a large mount of bit oblivious transfers.And with bit commitment with XOR,zero knowledge proofs are very easy.This PMPC protocol is conceptually simple and more efficient.The security and complexity of the protocol are also discussed in this paper.The private multi-party computation protocol proposed by Claude Crepeau etc.is not only complicated but very inefficient.This paper describes a new protocol with an efficient global commitment transfer sub-protocol.With a first two round string oblivious transfer,the protocol can avoid performing a large mount of bit oblivious transfers.And with bit commitment with XOR,zero knowledge proofs are very easy.This PMPC protocol is conceptually simple and more efficient.The security and complexity of the protocol are also discussed in this paper.

Journal of Circuits and SystemsJan 1, 20080 citations

Secure Multi-party Computation

Nigel Paul Smart

Information security and cryptographyNov 12, 201550 citations

Universally Composable Committed Oblivious Transfer With A Trusted Initializer

Adriana C. B. Pinto, Bernardo David, Jeroen van de Graaf +1 more

Committed Oblivious Transfer (COT) is a two-party primitive that combines one-out-of-two oblivious transfer with bit commitment. In the beginning of COT, a sender is committed to bits b0, b1 and a receiver to a choice bit c. In the end, the receiver is committed to bc without learning anything about b1-c, while the sender learns nothing about c. This primitive implies secure multi-party computation assuming that a broadcast channel is available. In this paper, we introduce the first universally composable unconditionally secure committed oblivious transfer protocol based on a Trusted Initializer (TI), which pre-distributes data to the parties. Our protocol builds on simple bit commitment and oblivious transfer protocols, using XOR commitments to prove simple relations in zero-knowledge. Besides providing very high security guarantees, our protocols are significantly simpler and more efficient than previous results, since they rely on pre-computed operations distributed by the TI.Committed Oblivious Transfer (COT) is a two-party primitive that combines one-out-of-two oblivious transfer with bit commitment. In the beginning of COT, a sender is committed to bits b0, b1 and a receiver to a choice bit c. In the end, the receiver is committed to bc without learning anything about b1-c, while the sender learns nothing about c. This primitive implies secure multi-party computation assuming that a broadcast channel is available. In this paper, we introduce the first universally composable unconditionally secure committed oblivious transfer protocol based on a Trusted Initializer (TI), which pre-distributes data to the parties. Our protocol builds on simple bit commitment and oblivious transfer protocols, using XOR commitments to prove simple relations in zero-knowledge. Besides providing very high security guarantees, our protocols are significantly simpler and more efficient than previous results, since they rely on pre-computed operations distributed by the TI.

Simpósio Brasileiro de Cibersegurança (SBSeg)Nov 19, 20120 citations

Committed Oblivious Transfer and Private Multi-Party Computation

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