Feat: GKR-Hashers

[Tabaie]

• Implements full hash functions for Poseidon2 and MiMC.
• Updates the Merkle Damgard hasher to implement the StateStorer interface.

Benchmark: For 27M constraints for 52K permutations on BLS12-377, using degree 17 gates. Attempts to use degree 2 and 4 gates proved counterproductive, resulting in 32M and 31M constraints, respectively.

[Copilot]

Pull Request Overview

This PR adds full hash implementations for Poseidon2 and MiMC, including GKR‐based compressors and parameter management for multiple curves, and updates related tests and benchmarks.

• Introduce Parameters type with GetDefaultParameters to unify Poseidon2 parameters across curves
• Refactor GKR compressor for Poseidon2 and add a new GKR MiMC compressor
• Update hash wrappers/tests to use new APIs and remove hardcoded curve assumptions

Reviewed Changes

Copilot reviewed 21 out of 21 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
std/permutation/poseidon2/poseidon2.go	Export Parameters fields, add GetDefaultParameters, unify constructors
std/permutation/poseidon2/gkr-poseidon2/gkr-poseidon2.go	Refactor NewGkrCompressor, generic gate registration & circuit definition
std/permutation/poseidon2/gkr-poseidon2/gkr-poseidon2_test.go	Update test helper signature, fix loop and assignment logic
std/permutation/gkr-mimc/gkr-mimc.go	New GKR‐MiMC compressor implementation
std/permutation/poseidon2/gkr-poseidon2/... (hash wrappers/tests)	Update Poseidon2 hash wrappers and tests for new APIs
internal/gkr/...	Simplify Println error handling across backends

Comments suppressed due to low confidence (3)

std/permutation/poseidon2/gkr-poseidon2/gkr-poseidon2_test.go:20

• You cannot range over an int. Use for i := 0; i < n; i++ or for i := range ins instead.

for i := range n {

std/hash/poseidon2/poseidon2_test.go:43

• You cannot use range on an int. Change to for i := 0; i < nbInputs; i++.

for i := range nbInputs {

std/permutation/poseidon2/gkr-poseidon2/gkr-poseidon2.go:235

• You cannot use range on an integer. Replace with a standard for i := 0; i < p.NbFullRounds/2; i++ loop.

for i := range p.NbFullRounds / 2 {

[Copilot]

[nitpick] The switch cases that copy RoundKeys for each curve are nearly identical. Consider extracting the loop into a helper to reduce duplication and ease future maintenance.