ERC-8004 — Trustless Agents

ERC-8004 defines three on-chain registries for autonomous AI agents: Identity, Reputation, and Validation. Tenzro implements ERC-8004 for Ethereum-family chains and provides native DID-based equivalents for the Tenzro ledger, with deterministic agentId = keccak256(DID).

The Three Registries

IdentityRegistry

Maps agentId (uint256) to an operator address, a DID, and an agent card URI. Anyone can register an agent they control. Operator updates require signature by the current operator.

Methods: register(did, operator, agentCardUri), getAgent(did), updateAgent(agentId, ...)

ReputationRegistry

Stores signed feedback records per target agent. Each feedback is a tuple of (target_agent, score ∈ [-128,127], reason_uri, issuer_sig). Aggregated reputation is computed off-chain and can be verified on-chain.

Methods: submitFeedback(targetDid, score, uri)

ValidationRegistry

Coordinates on-chain validation requests. An agent can be challenged to prove a claim (e.g., "I executed task X with result hash Y"). Validators stake TNZO and attest to the outcome.

Methods: requestValidation(subjectDid, dataHash, uri), attest(requestId, valid)

agentId Derivation

// Deterministic mapping: agentId = keccak256(DID)
tenzro_erc8004DeriveAgentId({ "did": "did:tenzro:machine:abc123..." })
  -> {
    did: "did:tenzro:machine:abc123...",
    agent_id: "0x9f3a8b2c..."
  }

This makes the agentId stable across chains — the same DID always maps to the same agentId whether registered on Ethereum, Base, or Tenzro ledger.

Calldata Encoding Helpers

Tenzro provides RPC helpers to encode calldata for the standard ERC-8004 registry functions. These can be used to construct transactions for any EVM chain with a deployed registry:

// Register an agent in the IdentityRegistry
tenzro_erc8004EncodeRegister({
  did: "did:tenzro:machine:...",
  operator: "0x...",
  agent_card_uri: "https://example.com/.well-known/agent.json"
})
  -> { calldata: "0x...", selector: "0x..." }

// Query an agent
tenzro_erc8004EncodeGetAgent({ did: "did:tenzro:machine:..." })

// Submit reputation feedback
tenzro_erc8004EncodeFeedback({
  target_did: "did:tenzro:machine:...",
  score: 100,        // int8
  uri: "ipfs://..."
})

// Request validation
tenzro_erc8004EncodeRequestValidation({
  subject_did: "did:tenzro:machine:...",
  data_hash: "0x...",
  uri: "ipfs://..."
})

CLI

tenzro erc8004 derive-id --did did:tenzro:machine:...
tenzro erc8004 encode-register --did ... --operator 0x... --uri https://...
tenzro erc8004 encode-feedback --target-did ... --score 100 --uri ipfs://...
tenzro erc8004 encode-validation --subject-did ... --data-hash 0x... --uri ipfs://...

Relationship to TDIP

TDIP and ERC-8004 are complementary:

TDIP provides the DID, delegation scope, and verifiable credentials infrastructure native to Tenzro ledger.
ERC-8004 projects those identities onto EVM chains for interoperability with the broader Ethereum agent ecosystem.
The Agent Card URI in IdentityRegistry typically points to a Google A2A-compatible agent descriptor.

Ecosystem Integration

The ERC-8004 calldata encoders work with any EVM chain where the registries are deployed — Ethereum mainnet, Base, Arbitrum, Optimism, and more. The Ethereum MCP server exposes eth_register_agent_8004 and eth_lookup_agent_8004 for direct ERC-8004 interactions.

→ Tutorial: Register an agent on ERC-8004