ERC-8004 Overview

ERC-8004 is a Trustless Agents standard that provides on-chain identity, reputation, and validation infrastructure for AI agents. It enables agents to establish verifiable identities, build reputation through interactions, and receive third-party assessments.

Why ERC-8004?

As AI agents become more autonomous and handle real value, users need ways to:

• Verify agent identity - Know which agent they're interacting with
• Assess trustworthiness - See an agent's track record before delegating tasks
• Enable accountability - Trace actions back to specific agent identities
• Build reputation - Allow good agents to differentiate from bad actors

ERC-8004 solves these problems with three interconnected on-chain registries.

The Three Registries

Identity Registry

The IdentityRegistry is an ERC-721 contract where each NFT represents an agent identity. Agent owners can attach arbitrary key-value metadata to their agent tokens.

+-----------------------------------------+
|           IdentityRegistry              |
+-----------------------------------------+
|  Agent #1 (NFT)                         |
|  |-- agentName: "TradingBot"            |
|  |-- agentType: "defi-trader"           |
|  |-- model: "claude-opus-4-5"           |
|  +-- status: "active"                   |
+-----------------------------------------+
|  Agent #2 (NFT)                         |
|  |-- agentName: "CustomerService"       |
|  |-- agentType: "support"               |
|  +-- capabilities: "refund,inquiry"     |
+-----------------------------------------+

Key features:

• ERC-721 compliant - agents can be transferred, traded, or held in multisigs
• Arbitrary metadata - store any key-value pairs on-chain
• Token URI support - link to off-chain agent specifications (IPFS, Arweave)

Reputation Registry

The ReputationRegistry tracks feedback from users who interact with agents. It uses cryptographic authorization to prevent spam while allowing legitimate feedback.

+-----------------------------------------+
|          ReputationRegistry             |
+-----------------------------------------+
|  Agent #1 Feedback                      |
|  |-- Client A: Score 85, tags: speed    |
|  |-- Client B: Score 92, tags: accuracy |
|  +-- Client C: Score 78, tags: cost     |
|                                         |
|  Summary: 3 reviews, avg 85             |
+-----------------------------------------+

Key features:

• Authorized feedback - Agent owners pre-authorize who can submit feedback
• Score range - 0-100 numeric scores for quantitative comparison
• Tag-based filtering - Filter feedback by category (reliability, speed, cost)
• Revocation - Clients can revoke their own feedback
• Responses - Any party can append responses to feedback

Validation Registry

The ValidationRegistry enables third-party validators (auditors, zkML verifiers, stakers) to assess agents and publish scored evaluations.

+-----------------------------------------+
|         ValidationRegistry              |
+-----------------------------------------+
|  Agent #1 Validations                   |
|  |-- Validator X: Score 95 (security)   |
|  |-- Validator Y: Score 88 (performance)|
|  +-- Validator Z: Score 92 (compliance) |
|                                         |
|  Summary: 3 validations, avg 92         |
+-----------------------------------------+

Key features:

• Request/Response flow - Agent owners request validation from specific validators
• Immutable requests - Request hashes cannot be overwritten (prevents hijacking)
• Progressive validation - Multiple responses possible per request
• Tag-based categorization - Filter by validation type

How the Registries Connect

                    +--------------------+
                    |  IdentityRegistry  |
                    |   (Agent NFTs)     |
                    +---------+----------+
                              |
                    +---------+---------+
                    |                   |
                    v                   v
         +------------------+  +------------------+
         |ReputationRegistry|  |ValidationRegistry|
         | (User Feedback)  |  | (Expert Audits)  |
         +------------------+  +------------------+

Both ReputationRegistry and ValidationRegistry require a reference to IdentityRegistry at deployment. They verify that agent IDs exist in the identity registry before accepting feedback or validation requests.

Security Model

ERC-8004 includes several security measures:

Comparison to Existing Standards

Use Cases

Trading Agent Reputation

A DeFi trading agent builds reputation over time. Users who delegate funds can check the agent's track record before trusting it with their assets.

Service Provider Discovery

Businesses deploy customer service agents with on-chain identities. Other agents can discover and verify service providers before routing requests.

Multi-Agent Collaboration

In multi-agent systems, agents can verify each other's identities and check reputation before collaborating on complex tasks.

Validator Networks

Specialized validators (security auditors, performance testers, compliance checkers) can assess agents and publish their findings on-chain.

Implementation

The Cairo implementation follows Starknet best practices:

• OpenZeppelin components - ERC-721, SRC5, ReentrancyGuard
• Poseidon hashing - For metadata key storage and request hashes
• ByteArray strings - Native Cairo string handling for metadata values
• SNIP-12 TypedData - For feedback authorization signatures

Contract Addresses

See the Deployment Guide for contract addresses and deployment instructions.

Next Steps

• Identity Registry - Full API reference for agent registration
• Reputation Registry - Full API reference for the feedback system
• Validation Registry - Full API reference for validator assessments
• Deployment Guide - Deploy your own ERC-8004 contracts