poseidon2-r1cs-bls12-381

R1CS Poseidon2 compress gadget over BLS12-381 Fr.

This crate matches:

• poseidon2-evm-bls12-381
• gnark-crypto fr/poseidon2 with (t=2, rF=8, rP=56) and feed-forward output

It is compress-only and keeps constants in source.

API

• compress(left, right) -> Scalar: native reference computation.
• gadget::compress_allocated(cs, left, right) -> AllocatedNum<Scalar>: R1CS gadget.

This crate is gadget-centric. A test-only circuit wrapper lives in tests/compress_vectors.rs to run vector conformance checks.

Test vectors

Vector fixtures are committed in-repo at tests/vectors.json.

Run tests:

cargo test