An Oblivious Transfer Protocol with Log-Squared Communication

• Published in: Information Security pp. 314 - 328
• Main Author: Lipmaa, Helger
• Format: Book Chapter
• Language: English
• Published: Berlin, Heidelberg Springer Berlin Heidelberg 2005
• Series: Lecture Notes in Computer Science
• Subjects: Computationally-private information retrieval; length-flexible additively homomorphic public-key cryptosystem; oblivious transfer
• ISBN: 9783540290018; 354029001X
• ISSN: 0302-9743; 1611-3349
• DOI: 10.1007/11556992_23

We propose a one-round 1-out-of-n computationally-private information retrieval protocol for ℓ-bit strings with low-degree polylogarithmic receiver-computation, linear sender-computation and communication Θ(klog2n+ℓlogn), where k is a possibly non-constant security parameter. The new protocol is receiver-private if the underlying length-flexible additively homomorphic public-key cryptosystem is IND-CPA secure. It can be transformed to a one-round computationally receiver-private and information-theoretically sender-private 1-out-of-n oblivious-transfer protocol for ℓ-bit strings, that has the same asymptotic communication and is private in the standard complexity-theoretic model.