Agora

Verifiable Off‑Chain Computation via Commit‑Reveal and XCM

System Architecture

Agora is a Polkadot parachain template extended with a verifiable computation marketplace. It enables parachains to outsource off‑chain jobs (API fetches, computations) to a network of staked workers. Results are verified on‑chain using a crypto‑economic commit‑reveal game. Cross‑parachain requests and result delivery use XCM. This instance has been obtained with paraid 5024 on the Paseo test network.

Live Walkthough

Watch Agora Walkthrough

Video Demo

Watch Agora Demo Video

Why Agora

• Cryptoeconomic Verification Without TEEs: Two-phase commit-reveal protocol (⁠ H(salt || result) ⁠) with on-chain hash verification prevents post-commitment manipulation. Byzantine fault tolerance via majority consensus without SGX dependencies.

• Incentive-Aligned Worker Marketplace: Staked workers face dual penalties—economic slashing + persistent reputation decay. Honest majority splits bounties; dishonest actors suffer compounding penalties, making long-term defection irrational.

• XCM-Native Interoperability: Cross-parachain job submission via ⁠ Transact ⁠ instruction, sovereign account fee payment, asynchronous result callbacks through HRMP channels. Native multi-asset bounty support via ⁠ MultiLocation ⁠ addressing without bridge trust assumptions.

• Hybrid Execution Model: OCWs handle I/O-bound tasks (API fetches, crypto ops) off-chain; only commit hashes and reveals touch on-chain storage. Deterministic ⁠ on_initialize ⁠ settlement ensures reproducible consensus, reward distribution, and reputation updates across all nodes—critical for cross-chain result verification.

Use Cases:

⁠•⁠ Oracle data aggregation: Request external API data (price feeds, weather, sports scores) from multiple workers, reach consensus on the correct value, and deliver verified results to DeFi protocols.

•⁠ Decentralized computation: Offload intensive computations (cryptographic operations, data processing, ML inference) to a distributed worker network without relying on a single centralized service.

•⁠ Cross-chain data verification: Enable parachains to request computation from other chains in the Polkadot ecosystem, leveraging specialized compute resources while maintaining trust through majority consensus.

•⁠ API reliability: When a single API endpoint is unreliable, multiple workers can fetch from different sources or endpoints, with the majority result being the canonical answer.

Why Polkadot Architecture is Ideal:

•⁠ ⁠Native cross-chain communication: XCM (Cross-Consensus Message Format) enables seamless job submission and result delivery between parachains without bridges or wrapping. Agora leverages this to create a truly interoperable computation marketplace.

•⁠ ⁠Shared security model: Parachains inherit security from the relay chain validators, eliminating the need for Agora to bootstrap its own validator set. This reduces costs and increases trust for users submitting jobs.

•⁠ ⁠Sovereign execution environment: As a parachain, Agora can customize its runtime specifically for computation marketplace logic (commit-reveal timing, reward distribution, slashing parameters) without constraints from other chains.

•⁠ ⁠Economic interoperability: Polkadot's native asset transfer via XCM allows job creators to pay bounties in their own parachain's token, while workers receive rewards in Agora's native token—all atomic and trustless.

•⁠ ⁠Scalability through specialization: Dedicated parachain slot allows Agora to optimize for high-throughput job processing without competing for block space with other applications. OCWs can process jobs off-chain and only submit commits/reveals on-chain.

•⁠ ⁠Future-proof upgrades: Runtime upgrades enable Agora to evolve its consensus mechanism, add new job types, or adjust economic parameters without hard forks, maintaining backward compatibility.

High‑Level Architecture

• Runtime (runtime/): FRAME‑based runtime with balances, collator pallets, XCM helpers, and the agora pallet. XCM is configured for local testing with permissive filters.
• Node (node/): Collator binary that runs the runtime, exposes RPC, and connects to the relay chain.
• Agora Pallet (pallets/agora/):
  • Job lifecycle: submit -> commit -> reveal -> finalize
  • Staking and bounty holds; rewards/slashing; simple reputation
  • Off‑Chain Worker (OCW) helpers for job execution and commit/reveal guidance
  • XCM client/handler for cross‑parachain job requests and result notifications
• Zombienet configs (zombienet-*.toml): Local networks with relay chain + 2 parachain instances for XCM demos.
• Scripts (JS/): Utilities to fund sovereign accounts, open HRMP channels, and run a cross‑chain job demo.

App Workflow

Repository Layout

• node/ – Collator service (AURA consensus, networking, RPC)
• runtime/ – Runtime types, pallet composition, XCM config (runtime/src/configs/xcm_config.rs)
• pallets/agora/ – Verifiable computation pallet
  • lib.rs – Storage, events, errors, extrinsics, hooks
  • functions.rs – Consensus, rewards/slashing, lifecycle processing
  • ocw.rs – Off‑chain worker execution helpers (simulated HTTP/compute), commit/reveal guidance
  • xcm_job_client.rs – Build/send XCM job requests, receive results
  • xcm_handler.rs – Handle incoming XCM job submissions, send results back
  • types.rs – Job, worker, commit/reveal, OCW types
• zombienet-xcm.toml – Relay + two parachains (IDs 1000, 2000) with XCM tracing enabled
• JS/setup-hrmp.js – HRMP channel setup, sovereign funding, and agora.requestRemoteJob demo

Build

Prereqs: Rust toolchain (nightly as per rust-toolchain.toml), wasm32 target, Node.js (for scripts), and a polkadot relay binary.

# From repo root
 cargo build --release -p parachain-template-node --bin parachain-template-node

# Optional: install the collator binary somewhere on PATH
sudo cp target/release/parachain-template-node /usr/local/bin/

# Ensure a polkadot relay node is available on PATH (or provide absolute path in Zombienet)
sudo cp polkadot /usr/local/bin/polkadot

Run: Local Multi‑Chain Network (Zombienet)

This repo includes zombienet-xcm.toml to boot a relay chain (rococo‑local) and two parachain instances for XCM testing.

# Example with zombienet (ensure you have it installed)
zombienet -p native spawn zombienet-xcm.toml

Key ports (from zombienet-xcm.toml):

• Relay RPC/ws: 9944/9988
• Para 1000 RPC/ws: 9946/9990
• Para 2000 RPC/ws: 9947/9991

HRMP + XCM Demo

Use the provided Node.js script to fund sovereign accounts, open HRMP channels, and dispatch a cross‑chain job request.

pnpm i || npm i
node JS/setup-hrmp.js

The script performs:

• Funds sovereign accounts (relay and cross‑parachain)
• Opens HRMP channels 1000 ↔ 2000 using XCM Transact
• Debug.js to verify the status of the parachains.

Agora Pallet – On‑Chain API

Extrinsics (selected):

• agora.submitJob(job_type_id, input_data, bounty, reputation) – Submit a local job with a bounty hold
• agora.registerWorker(stake) / agora.unregisterWorker() – Worker enrollment with staking
• agora.commitResult(job_id, salt, result_hash) – Commit phase
• agora.revealResult(job_id, result) – Reveal phase; pallet verifies salted hash
• agora.finalizeJob(job_id) – Finalizes by consensus (auto‑finalization also runs in on_initialize)
• agora.requestRemoteJob(dest_para_id, input_data, bounty, reputation) – Send cross‑para job via XCM

Events include job submission, commits/reveals, finalization, rewards/slashing, and XCM‑related notifications.

Storage highlights:

• Jobs, Workers, Commits, Reveals, Results, PendingJobs, RemoteJobInfo, NextJobId, JobNonce.

Consensus and rewards:

• Majority of reveals determine the canonical result.
• Honest workers split the bounty; dishonest workers lose reputation and have stake reduced.

Off‑Chain Worker (OCW)

• Scans for pending jobs and simulates execution for:
  • API requests: returns simulated payloads (upgradeable to real HTTP with proper signing/validation)
  • Computation jobs: hash/math/crypto/json toy tasks
• Generates salted commits and logs ready‑to‑submit commitResult/revealResult transactions.
• Automation of signed extrinsic submission can be enabled in future work.

Configuration and Parameters

Runtime (runtime/src/lib.rs) sets:

• Block time: 6s; weight/fee mapping
• Agora constants: MinWorkerStake, MinJobBounty, commit/reveal durations, limits
• XCM router: Parent UMP + XCMP; permissive Barrier and Everything filters for local testing

Harden for production:

• Restrict XCM execute/send filters; require paid execution with proper fee trading
• Tighten LocationToAccountId conversions and origins
• Replace simulated OCW HTTP with a secure, signed, and verifiable approach