did:nft

The NFT DID Method (did:nft) enables any non-fungible token to function as a decentralized identifier, where the NFT's owner becomes the DID controller. This method creates a bridge between the world of blockchain-based NFTs and decentralized identity systems, leveraging the Ceramic Network for resolution and the Chain Agnostic Improvement Proposals for cross-chain compatibility.

The method works by converting NFT ownership into DID control, allowing any NFT across different blockchains to become a functional digital identifier. When an NFT changes ownership through a blockchain transaction, the DID controller automatically updates to reflect the new owner. This creates a dynamic identity system where control of digital resources can be transferred alongside NFT ownership.

Key features include:

• Cross-chain compatibility through CAIP-19 Asset ID standards
• Automatic controller updates based on NFT ownership
• Integration with the Ceramic Network for DID resolution
• Support for multiple NFT standards (initially ERC721)
• Blockchain-agnostic design

Technical Implementation:

1. DID Generation and Structure

• Format: did:nft:<CAIP-19-Asset-ID>
• Asset ID format replaces / with _ for DID spec compliance
• Example: did:nft:eip155:1_erc721:0x06012c8cf97BEaD5deAe237070F9587f8E7A266d_771769

2. Resolution Process

3. Extract Asset ID from the identifier

4. Look up NFT owner on the respective blockchain

5. Convert owner address to CAIP-10 Account ID

6. Query Ceramic Network for associated DID using caip10-link

7. Construct DID Document with:

   • Controller property (if found)
   • Verification methods
   • Metadata (creation and update timestamps)

8. Security and Key Management

• Inherits security properties from:
  • Underlying blockchain networks
  • Ceramic Network protocol
• Supports version control through blockchain timestamps
• Implements BlockchainVerificationMethod2021

4. Unique Characteristics

• Dynamic ownership transfer through NFT transactions
• Cross-chain interoperability through CAIP standards
• Extensible metadata support
• Versioning capabilities through blockchain timestamps

5. Technology Stack

• Blockchain Layer:
  • Support for multiple chains through CAIP standards
  • Initially focused on ERC721 tokens
• Resolution Layer:
  • Ceramic Network for DID resolution
  • caip10-link document type
• Standards:
  • CAIP-19 for Asset identification
  • CAIP-10 for Account identification
  • W3C DID Core specification compliance