Abstract

We propose a protocol for oblivious transfer that is unconditionally secure under the sole assumption that the memory size of the receiver is bounded. The model assumes that a random bit string slightly larger than the receiver's memory is broadcast (either by the sender or by a third party). In our construction, both parties need memory of size in (n 2 2 ) for some < 1 2 , when a random string of size N = n 2 is broadcast, for > > 0, whereas a malicious receiver can have up to N bits of memory for any < 1. In the course of our analysis, we provide a direct study of an interactive hashing protocol closely related to that of Naor et al. [27]. 1. Introduction Oblivious transfer is an important primitive in modern cryptography. It was introduced to cryptography in several variations by Rabin and Even et al. [29, 20] and had been studied already by Wiesner [31] (under the name of "multiplexing "), in a paper that marked the birth of quantum cryptography. Oblivious t...

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