NearDIDRegistry

A smart contract implemented in Rust for the NEAR Protocol that functions as a decentralized identifier (DID) registry. It allows ownership management, delegation, attribute assignment, and nonce tracking for DIDs represented by base58-encoded Ed25519 public keys.

🔐 Cryptographic Foundation

• Signature Algorithm: Ed25519 (used externally for signing/verifying JWTs)

• Key Encoding:

  • Base58 encoding for public keys in did:near:<base58> format
  • Base64url encoding in JWT proofs

• Hashing and Storage: Data keys are tuples of strings and Vec<u8>, stored using LookupMap from near_sdk

🧠 Core Concepts

• Each identity is a String (base58 public key or NEAR account).
• Delegates and attributes are valid for a given duration (in seconds).
• Only the current owner of an identity can modify its state.

📦 Contract Storage

Field	Description
owners	Maps identity to current owner (also a String)
delegates	Maps (identity, type, delegate) to expiration
attributes	Maps (identity, name, value) to expiration
changed	Maps identity to block height of last change
nonce	Monotonic counter for off-chain use (signatures)

---

⚙️ Public Methods

identity_owner(identity: String) -> String

Returns the current owner of a DID. Defaults to self-owned if not registered.

change_owner(identity: String, new_owner: String)

Changes the owner of a DID. Only callable by current owner.

add_delegate(identity: String, delegate_type: String, delegate: String, validity_secs: u64)

Registers a delegate for a DID, valid for the given duration.

revoke_delegate(identity: String, delegate_type: String, delegate: String)

Revokes a delegate by setting expiration to 0.

valid_delegate(identity: String, delegate_type: String, delegate: String) -> bool

Returns true if the delegate is still valid.

set_attribute(identity: String, name: String, value: Vec<u8>, validity_secs: u64)

Assigns an attribute (e.g. public key, service endpoint) to a DID.

revoke_attribute(identity: String, name: String, value: Vec<u8>)

Revokes an attribute by setting its expiration to 0.

valid_attribute(identity: String, name: String, value: Vec<u8>) -> bool

Returns true if the attribute is still valid.

get_nonce(identity: String) -> u64

Returns the current nonce of the identity.

increment_nonce(identity: String)

Increments the nonce by 1. Useful for signed interactions.

get_changed(identity: String) -> u64

Returns the block height of the last change made to the identity.

---

🧪 Example cURL Calls (via RPC)

Replace your-contract.testnet and identity accordingly.

🔍 View owner

curl -X POST https://rpc.testnet.near.org \
  -H 'Content-Type: application/json' \
  -d '{
    "jsonrpc": "2.0",
    "id": "dontcare",
    "method": "query",
    "params": {
      "request_type": "call_function",
      "finality": "final",
      "account_id": "your-contract.testnet",
      "method_name": "identity_owner",
      "args_base64": "eyJpZGVudGl0eSI6ICJkaWQ6bmVhcjpDaGVjaw=="  
    }
  }'

args_base64 is the base64-encoded JSON: { "identity": "did:near:Check" }

🔐 Change owner (via Near CLI)

near call your-contract.testnet change_owner '{"identity": "did:near:Check", "new_owner": "did:near:NewKey"}' --accountId your-account.testnet

➕ Add delegate

near call your-contract.testnet add_delegate '{"identity": "did:near:Check", "delegate_type": "veriKey", "delegate": "did:near:OtherKey", "validity_secs": 3600}' --accountId your-account.testnet

🗑️ Revoke attribute

near call your-contract.testnet revoke_attribute '{"identity": "did:near:Check", "name": "did/pub/Ed25519/veriKey/base64", "value": "a2V5VmFsdWU="}' --accountId your-account.testnet

value should be base64-encoded.

---

✅ Example DID Document (based on registry)

{
  "@context": "https://w3id.org/did/v1",
  "id": "did:near:CF5Ri...",
  "verificationMethod": [
    {
      "id": "did:near:CF5Ri...#owner",
      "type": "Ed25519VerificationKey2018",
      "controller": "did:near:CF5Ri...",
      "publicKeyBase58": "CF5RiJYh4EVmEt8UAD..."
    }
  ],
  "authentication": ["did:near:CF5Ri...#owner"],
  "assertionMethod": ["did:near:CF5Ri...#owner"]
}

---

🧠 Notes

• Designed for interoperability with did-jwt, JwtProof2020, and NEAR-based wallets.
• Suitable for creating lightweight DID registries using only Ed25519 keys.
• Compatible with did:near:<base58PublicKey> and optionally example.testnet as identity.