International Association
for Cryptologic Research

The relationship between oblivious transfer (OT) and public-key encryption (PKE) has been studied by Gertner et al. (FOCS 2000). They showed that OT can be constructed from special types of PKE, i.e., PKE with oblivious sampleability of public keys or ciphertexts. In this work, we give new black-box constructions of OT from PKE without any oblivious sampleability. Instead, we require that the PKE scheme is rerandomizable, meaning that one can use the public key to rerandomize a ciphertext into a fresh ciphertext. We give two different OT protocols with different efficiency features based on rerandomizable PKE. For $1$-out-of-$n$ OT, in our first OT protocol, the sender has sublinear (in $n$) cost, and in our second OT protocol, the cost of the receiver is independent of $n$. As a comparison, in the PKE-based OT protocols of Gertner et al., both the sender and receiver have linear cost.