Research
Problems we're looking into but haven't been fleshed out fully.
LeanPIR: Novel Double-Stateless GPU-Optimized Scheme
We are actively working on a stateless scheme (both client and server) that is tailored to GPU optimization. We expect to publish this with a reference implementation in Q2 2026.
PIR for Merkle Trees
Clients need not just leaf values but Merkle proofs to verify state against roots. Retrieving these proofs privately adds overhead — either by running separate PIR queries per tree level, or by pre-attaching proof paths to database entries (increasing storage). UBT's binary structure is significantly cheaper here than MPT's hexary branching. We are exploring hybrid strategies that balance query count against storage blowup. See section 8 of the design post for the analysis.
Verifiable UBT over MPT
The binary state trie can be adopted today by proving equivalence to the canonical MPT. This reduces PIR database size for hosting Merkle roots and simplifies optimizations like SNARKification. We are working on getting EL client(s) EIP-7864-ready as a first step, then having it shadow mainnet with real-time equivalence proving between the application of every block to both chains, using a zkVM.
SNARKifying Archival State to Reduce DB Size
PIR databases for archival Ethereum state can grow to terabytes. If we can replace Merkle proofs with succinct SNARK proofs of state validity, the database shrinks significantly — clients verify a proof instead of fetching and hashing Merkle paths. The idea is to chain recursive zkVM proofs per block, so any historical balance, nonce, or codehash lookup can be verified against a single succinct proof rather than full Merkle paths. See section 8 of the design post for details.
Delegating Hint Generation in Interactive-Hint Schemes
Interactive-hint schemes like Plinko and RMS24 achieve sublinear online server time but require clients to stream entire databases during hint generation. Delegating this to a server via FHE or MPC could reduce both computational and bandwidth burden on clients, though this remains prohibitively expensive with current constructions.
Concretely Efficient DEPIR
Doubly Efficient PIR (DEPIR) combines client-stateless simplicity with asymptotically sublinear server-side cost. However, constants in existing asymptotic bounds place current constructions orders of magnitude behind practical PIR schemes on real databases. Achieving concrete efficiency would dramatically simplify the PIR landscape: a single client-stateless scheme with sublinear per-query cost could serve all data slices.