Overview

The goal of this grant is to build out a Webb mixer using Harmony's EVM and bulletproof precompiles.

https://github.com/webb-tools/anon

Deliverables

• A Webb EVM Mixer repo to be delivered and usable in Harmony ecosystem.
  • Merkle trees using Poseidon hash function
• Bulletproof precompiles for verifying bulletproof R1CS proofs on-chain.
• Poseidon hash precompiles for hashing elements using Poseidon over Curve25519.
  • Over bytes32 elements.
• Webb Mixer UI support for Harmony where users can use the mixer with a Harmony RPC.

Webb EVM Mixer (1-2 months)

• Cryptocurrency mixer contracts with Poseidon hash precompile support over bytes32
  • Hashes will be computed over scalar field of Curve25519
• Extend verifier contracts with Bulletproofs verification precompile support.
  • Use dalek-cryptography bulletproofs R1CS.
• Incremental construction of merkle trees on-chain using Poseidon hash.
• Support for relay-able transactions.

Precompiles (1 month)

• Bulletproof proof verification precompile written in Rust w/ Golang bindings.
• Poseidon hash precompile using Curve25519 written in Rust w/ Golang bindings.