Yugo Cabrio and Changmin Cho completed Milestone #1 of the UltraHonk Verifier for Soroban project, delivering a pure Rust implementation of the UltraHonk proof verifier that enables Noir/Barretenberg proofs to be verified on Stellar Soroban. After discovering incompatibility with the Taceo-labs extraction approach, they implemented the verifier from scratch in Rust with full CI/CD integration.
The UltraHonk Verifier for Soroban Milestone #1 report documents the development of a Rust-based verifier for Noir proofs targeting Stellar Soroban. The team initially attempted to extract and adapt an existing Taceo-labs Rust verifier but discovered it was incompatible with modern Barretenberg proof output, forcing a pivot to a from-scratch implementation. Over five weeks, they built a complete verifier in pure Rust covering BN254 field operations, Fiat-Shamir transcripts, sumcheck, and batch opening protocols. The deliverable includes a public MIT-licensed repository with comprehensive CI/CD that automatically builds sample Noir circuits and runs verification tests. Milestone #2 will focus on removing standard library dependencies for Soroban compatibility and deploying the verifier as a Soroban smart contract.