Skip to main content

Porting the RISC Zero Groth16 Verifier from Solidity to Rust for Stellar

Overview​

This guide outlines the process of porting the RISC Zero Groth16 Verifier from Solidity to Rust and compiling it into WebAssembly (WASM) for use in the Stellar Soroban environment. The goal is to enable on-chain verification of zero-knowledge proofs (ZK proofs) on Stellar's decentralized and cost-efficient infrastructure.

Justification​

1. WebAssembly Compatibility​

Stellar’s Soroban platform relies on WASM for executing smart contracts. Rust’s first-class support for WASM ensures seamless compilation of the verifier, making it deployable and executable in Stellar’s runtime environment.

2. Flexibility and Ecosystem Support​

Rust’s ecosystem provides access to robust cryptographic libraries, such as Arkworks, enabling efficient handling of pairing-based operations critical for Groth16 verification. This flexibility is crucial for adapting and optimizing the verifier for Stellar’s requirements.

3. Cost Efficiency on Stellar​

Stellar’s focus on low-cost transactions makes Rust-compiled WASM an ideal choice. The optimized code reduces computational overhead and ensures affordable on-chain proof verification.

High-Level Steps​

1. Understand the Solidity Verifier Contract​

  • Identify key functions, such as:
    • verifyProof: Verifies Groth16 proofs using cryptographic primitives.
    • Data structures for proofs, verification keys, and elliptic curve (EC) operations.

2. Porting Core Logic to Rust​

  • Translate the core cryptographic operations from Solidity to Rust, leveraging libraries like Arkworks for pairing checks and proof validation.
  • Separate cryptographic operations (e.g., pairing checks) from Solidity-specific constructs like msg.sender and storage patterns.
  • Ensure that the design adheres to WASM compatibility requirements, avoiding unsupported system calls or complex dependencies.

3. Testing and Validation​

  • Conduct unit and integration tests to validate the verifier’s accuracy and performance against known Groth16 proofs.
  • Simulate execution in WASM environments to identify and resolve compatibility issues.

4. Optimization for WASM​

  • Minimize the size of the compiled WASM module to meet Stellar’s on-chain storage constraints.
  • Use tools like wasm-opt to reduce code size and enhance execution efficiency.

5. Deployment and Integration with Soroban​

  • Deploy the compiled WASM module to Stellar’s Testnet environment for initial testing.
  • Develop a wrapper Soroban smart contract to interface with the verifier, exposing its functionality to the Stellar ecosystem.

Expected Impact​

  1. Interoperability: Enables seamless integration of Risc Zero's generalized zero-knowledge proof verification within Stellar’s decentralized financial applications.
  2. Enhanced Efficiency: Faster and more reliable on-chain verification of Groth16 proofs.
  3. Security: Leverages Rust’s memory safety guarantees and cryptographic libraries for robust and secure implementation.