Post-quantum Public-Key Pseudorandom Correlation Functions for OT

Public-key pseudorandom correlation functions (PK-PCF) are an exciting recent primitive introduced to enable "non-interactive key exchange for secure computation". Despite significant advances in the group-based setting, success in the post-quantum regime has been much more limited. To the best of our knowledge, there does not exist even a single efficient candidate post-quantum PK-PCF for the standard string oblivious transfer (OT) correlation.

In this work, we address this gap by constructing the first efficient lattice-based public-key PCF for the string OT correlation. Our PK-PCF generates a few hundred OTs per second, and requires a large but manageable public key size (a few hundred megabytes). In contrast, the only previous lattice-based non-public-key PCF, proposed in the very recent work of Hasler, Reisert and Küsters (Asiacrypt 2025), can generate up to 9 OT/s and has key sizes of several gigabytes.