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ERC-8004 is an Ethereum standard for agent identity. It gives AI agents a verifiable, on-chain identity that is independent of the wallet they use to transact. In b402, this identity layer connects wallets, reputation, and delegation into a single framework.

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Why Agents Need On-Chain Identity

Without identity, an agent is just a private key. There is no way to distinguish a trusted agent from a new one, no way to delegate authority, and no accountability if something goes wrong. ERC-8004 solves this by providing:
  • Reputation: Payment history and behavior are linked to a persistent identity, not a disposable wallet address
  • Delegation: One agent can authorize another to act on its behalf, with verifiable on-chain proof
  • Accountability: Identity owners can be held responsible for their agents’ actions
  • Interoperability: A single identity works across protocols and applications

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How It Works

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Identity NFT

An ERC-8004 identity is an on-chain NFT (non-fungible token) minted to a wallet address. This NFT serves as the agent’s credential. It is non-transferable by default, binding the identity to its original owner. 
Owner Wallet (0xABC...) --[mint]--> Agent Identity NFT (tokenId: 42)
The identity NFT contains metadata about the agent: its name, capabilities, and the wallets it controls.

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Wallet Linking

Both EOA and smart wallets can be linked to an ERC-8004 identity. A single identity can control multiple wallets:
Wallet TypeHow It Links
EOAOwner signs a message linking the EOA to the identity
Smart Wallet (Nexus)The smart wallet’s owner address is linked to the identity
Once linked, every payment made by those wallets contributes to the identity’s on-chain reputation.

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Reputation-Linked Signing

When an agent signs a payment (EIP-712 or UserOp), the identity layer allows verifiers to look up:
  1. Who is this agent? - Resolve the signing wallet to an ERC-8004 identity
  2. What is their history? - Query payment volume, frequency, and success rate
  3. Are they trusted? - Check reputation score derived from on-chain activity
Sellers can use this information to offer tiered pricing, skip verification steps for trusted agents, or reject unknown agents entirely.

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Delegation

ERC-8004 supports delegation, where one identity grants another the authority to act on its behalf: 
Primary Identity (Alice) --[delegate]--> Sub-Agent Identity (Bot-1)
Delegation is useful for:
  • Multi-agent systems: A primary agent delegates payment authority to worker agents
  • Organizational hierarchies: A company identity delegates to department-level agents
  • Temporary access: Time-bound delegation that expires automatically
Delegation is recorded on-chain and can be verified by any party without trusting the delegator.

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Integration with b402

In b402, the identity layer is optional but recommended for agents that need:
  • Persistent reputation across multiple smart wallets
  • Delegation of payment authority to sub-agents
  • Higher trust levels with sellers (potentially lower fees or priority access)
Both the EOA and Smart Wallet payment flows work with or without an ERC-8004 identity. The identity adds a trust layer on top of the existing payment infrastructure.

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