[Resource Topic] 2001/073: Efficient oblivious transfer schemes

Welcome to the resource topic for 2001/073

Efficient oblivious transfer schemes

Authors: Wen-Guey Tzeng


In this paper we propose a very efficient
(string) OT_n^1 scheme
for any n\geq 2.
We build our OT_n^1 scheme from fundamental cryptographic
techniques directly.
It achieves optimal efficiency in the number of rounds
and the total number of exchanged messages for the case
that the receiver’s
choice is unconditionally secure.
The computation time of our OT_n^1 scheme is very
efficient, too.
The receiver need compute 2 modular
exponentiations only no matter how large n is,
and the sender need compute 2n modular exponentiations.
Furthermore, the system-wide parameters need not change
during the lifetime of the system and are {\em universally
That is, all possible receivers and senders use the same
parameters and need no trapdoors specific to each of them.
For our OT_n^1 scheme, the privacy of the receiver’s choice
is unconditionally secure and the privacy of
the un-chosen secrets is at least as strong as the hardness
of the decisional Diffie-Hellman problem.
We extend our OT_n^1 scheme to distributed oblivious
transfer schemes.
Our distributed OT_n^1 scheme takes full advantage of
the research results of secret sharing and is conceptually
It achieves better security than
Noar and Pinkas’s scheme does in many aspects.
For example, our scheme is secure against collusion of R
and t-1 servers
and it need not restrict R to contact at most t servers,
which is difficult to enforce.
For applications, we present a method of transforming any
single-database PIR
protocol into a symmetric PIR protocol with only one extra
unit of communication cost.

ePrint: https://eprint.iacr.org/2001/073

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