Protocol overview

Protocol overview

The draft composes ERC-721 or ERC-1155 metadata with Sign-In with Ethereum. It standardizes the missing interoperability boundary without defining storage, encryption, delegation persistence, or an onchain discovery registry.

Flow

1. Public token metadata advertises a safe preview and an absolute HTTPS private_media_uri.
2. An unauthenticated request returns 401 Unauthorized and a same-origin SIWE challenge URI.
3. The challenge binds one domain, chain, token, account, signer, and exact protected resource.
4. The resource server verifies the signature, atomically consumes the nonce, and rechecks current ownership, balance, approval, or explicit delegation.
5. The authorized response returns private metadata whose image can replace the public preview.

Clients that do not implement the draft continue rendering ordinary public metadata.

For exact URI rules, challenge fields, resource binding, verification order, and response behavior, read the official ERC-8291 draft (open PR #1801).