(Efficient) Universally Composable Oblivious Transfer Using a Minimal Number of Stateless Tokens

• Published in: Journal of cryptology Vol. 32; no. 2; pp. 459 - 497
• Main Authors: Choi, Seung Geol, Katz, Jonathan, Schröder, Dominique, Yerukhimovich, Arkady, Zhou, Hong-Sheng
• Format: Journal Article
• Language: English
• Published: New York Springer US 15-04-2019; Springer Nature B.V
• Subjects: Access control; Algorithms; Coding and Information Theory; Combinatorics; Communications Engineering; Computational Mathematics and Numerical Analysis; Computer Science; Encryption; Networks; Probability Theory and Stochastic Processes; Statelessness; Universal composability; Oblivious transfer; Hardware tokens; Secure computation
• ISSN: 0933-2790; 1432-1378
• DOI: 10.1007/s00145-018-9288-x

We continue the line of work initiated by Katz (Eurocrypt 2007) on using
tamper-proof hardware tokens
for universally composable secure computation. As our main result, we show an oblivious-transfer (OT) protocol in which two parties each create and transfer a single, stateless token and can then run an unbounded number of OTs. We also show a more efficient protocol, based only on standard symmetric-key primitives (block ciphers and collision-resistant hash functions), that can be used if a
bounded
number of OTs suffice. Motivated by this result, we investigate the number of stateless tokens needed for universally composable OT. We prove that our protocol is
optimal
in this regard for constructions making
black-box
use of the tokens (in a sense we define). We also show that nonblack-box techniques can be used to obtain a construction using only a single stateless token.