Oblivious Transfer with a Memory-Bounded Receiver

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 (n2 2 ) for some < 12 , when a random string of size N = n2 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].