Symmetric-Style Oblivious Lattice Evaluation

Oblivious Pseudorandom Functions (OPRFs) are a foundational cryptographic primitive that requires public-key cryptography. The challenge of designing post-quantum OPRFs remains open, as many existing constructions either lack the desired security guarantees or are computationally intensive. While elliptic curve-based OPRFs are relatively efficient compared to more heavy weight blind signatures, post-quantum constructions, particularly those based on lattices, don't have a clear advantage over blind signatures. One promising direction is the OPRF Leap, a construction that eliminates the need for zero-knowledge proofs and enables oblivious evaluation of a lattice-based PRF using only oblivious transfer. While it’s not a direct replacement for current solutions due to its preprocessing overhead, it shows significant promise for repeated execution scenarios, such as in private set intersection applications. This talk will introduce Leap, discuss open challenges and point to potential directions for future research.