Publications: Abstract

# Oblivious Transfer with a Memory-Bounded Receiver

## Christian Cachin and Claude Cr{é}peau and Julien Marcil

 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 $q(n^{2-2 a})$ for some $a<\frac{1}{2}$, when a random string of size $N=n^{2- a- b}$ is broadcast, for $a> b>0$, whereas a malicious receiver can have up to $g N$ bits of memory for any $g<1$. In the course of our analysis, we provide a direct study of an interactive hashing protocol closely related to that of Naor et al. NOVY98.