did:key

DID:key is a lightweight, non-registry based Decentralized Identifier method that generates DIDs directly from cryptographic public keys. Unlike blockchain-based DID methods, it requires no external infrastructure or registries, making it ideal for ephemeral and single-use identity scenarios.

The method creates a deterministic mapping between public keys and DID Documents, where each DID is derived from the public key using Multibase and Multicodec encoding. This approach provides a simple way to represent cryptographic keys as DIDs while maintaining the core benefits of the DID architecture.

Key characteristics:

• No external dependencies or blockchain requirements
• Supports multiple cryptographic key types including Ed25519, X25519, Secp256k1, P-256, P-384, P-521, RSA, and BLS12381
• Immutable by design - no update or deactivate operations
• Ideal for ephemeral use cases and scenarios with hardware-isolated keys
• Includes built-in support for both signature verification and key agreement

The method is particularly suited for:

• Short-lived authentication scenarios
• Single-use verification keys
• Hardware-protected key material
• Lightweight identity systems
• Testing and development environments

Technical Details:

1. DID Generation and Structure:

• Format: did:key:<multibase-encoded-public-key>
• Public key is encoded using multicodec and base58-btc encoding
• Includes key type identifier and raw key bytes

2. Resolution Process:

• Purely deterministic - no external lookups needed
• Decodes the key material from the DID string
• Expands into a complete DID Document with verification methods

3. Key Management:

• Supports multiple key types with different prefixes
• Automatic derivation of encryption keys from signing keys
• No key rotation capability by design

4. Security Features:

• Hardware isolation recommended for long-term use
• Built-in support for signature verification
• Integrated key agreement capabilities

5. Technology Stack:

• Multibase encoding framework
• Multicodec for key type identification
• Standard cryptographic primitives
• JSON-LD contexts for semantic interoperability

The method implements the core W3C DID specification while prioritizing simplicity and minimal infrastructure requirements.