Trustless Monero-Starknet Atomic Swaps Using DLEQ Proofs

šŸ“œ Development Proposals
1

Weā€™ve built a prototype atomic swap bridge that enables trustless XMR ā†” STRK/ETH exchanges on Starknet L2. This brings privacy-preserving currency to Starknetā€™s DeFi ecosystem without custodians, bridges, or KYC.

What This Enables for Starknet

  • Trustless swaps between XMR and Starknet assets using cryptographic binding via DLEQ proofs
  • Ultra-low gas costs: ~$0.01-0.05 per swap verification (~270k-440k gas)
  • Privacy-respecting gateway to DeFi for Monero users
  • No bridges or custodians - pure cryptographic security

Cairo Implementation Highlights

The implementation leverages Starknetā€™s Cairo VM capabilities:

  1. DLEQ Proof Verification: On-chain verification using Garaga v1.0.1 MSM library for elliptic curve operations
  2. BLAKE2s Challenge Computation: Gas-optimized at ~500k gas for full verification
  3. Production-Grade Libraries: OpenZeppelin Cairo Contracts v2.0.0 for security primitives
  4. Ed25519 Point Operations: Efficient scalar multiplication and point compression/decompression

Protocol Flow

  1. Alice generates secret scalar t and creates adaptor signature
  2. Alice deploys AtomicLock contract on Starknet with:
    • Hashlock H = SHA-256(t)
    • Adaptor point T = tĀ·G (Ed25519)
    • DLEQ proof proving āˆƒt: SHA-256(t) = H āˆ§ tĀ·G = T
  3. Bob verifies DLEQ proof on-chain, unlocks contract by revealing t
  4. Alice detects secret reveal via Unlocked event, completes Monero transaction

Current Development Status

Completed:

  • BLAKE2s challenge compatibility between Rust and Cairo
  • DLEQ proof generation (Rust) and verification (Cairo)
  • Test suite with 139 production-grade test vectors
  • CI/CD workflow with automated testing
  • Informal security audit of critical paths

in Progress:

  • Web interface for testnet experimentation
  • Sepolia testnet deployment
  • Race condition mitigations (two-phase unlock, watchtower service)

Technical Resources

GitHub: GitHub - omarespejel/monero-starknet-atomic-swap: Cross-chain atomic swap: Monero adaptor signatures + Starknet Cairo contracts with ED25519 MSM verification and DLEQ proofs

Known Limitations

This is alpha software under active development:

  • Protocol-level race condition exists
  • Monero integration uses simplified adaptor signatures, not full CLSAG
  • External security audit pending
  • Recommended for small amounts only (under $100 equivalent) until v0.8.0 mitigations

Iā€™m available to discuss Cairo implementation details, Starknet/Cairo technical specifics, and collaboration opportunities

Updates will be posted here as development progresses. Community feedback is essential for building robust infrastructure

Disclaimer: This is experimental software under active development. Do not use with real funds without security audit

2

Hey,

idk if normal but the repo isnā€™t public (or wrong link).
Would like to have a look :slight_smile:

G

3

Hey @gaetbout! The repo is open now, just had some visibility issues initially. You can check it out here: GitHub - omarespejel/monero-starknet-atomic-swap: Cross-chain atomic swap: Monero adaptor signatures + Starknet Cairo contracts with ED25519 MSM verification and DLEQ proofs

Feel free to take a look and let me know if you have any questions or feedback!

4

Looks great. I think XMR to STRK could bring some great privacy options to Starknet. Currently obtaining and selling XMR can be troublesome, especially with a lot of CEXā€™s no longer trading it.

Is there a road map to when this could possibly be a reality?