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W3C-compliant Decentralized Identity Registry, Soulbound NFTs, and on-chain reputation

The Identity module (contracts/identity/) implements W3C-compliant Decentralized Identifiers (DIDs), soulbound identity NFTs, and on-chain reputation linked to the Karma governance system.

DID Registry

The DIDRegistry stores DID documents on-chain following the W3C DID Core specification. Each DID is identified by its Ethereum address and can have multiple delegates, attributes, and service endpoints.

import "@luxfi/contracts/identity/DIDRegistry.sol";

DIDRegistry registry = DIDRegistry(REGISTRY_ADDRESS);

// Register a DID attribute (e.g., service endpoint)
registry.setAttribute(
    identity,
    "did/svc/MessagingService",
    "https://messaging.example.com",
    86400  // validity in seconds
);

// Add a delegate (e.g., signing key)
registry.addDelegate(
    identity,
    "sigAuth",
    delegateAddress,
    86400
);

// Revoke a delegate
registry.revokeDelegate(identity, "sigAuth", delegateAddress);

DID Format

Lux DIDs follow the format:

did:lux:0x1234...abcd

The DID document is constructed from on-chain events (attribute changes, delegate additions) and resolved by the DIDResolver.

DID Resolver

Resolves a DID to its full DID document by reading the event log from the registry.

import "@luxfi/contracts/identity/DIDResolver.sol";

DIDResolver resolver = DIDResolver(RESOLVER_ADDRESS);

// Check if identity is valid
bool valid = resolver.isValidDID(identity);

// Get delegate validity
bool isDelegate = registry.validDelegate(
    identity, "sigAuth", delegateAddress
);

Premium DID Registry

Extended DID features including human-readable names, verified status, and Karma integration.

import "@luxfi/contracts/identity/PremiumDIDRegistry.sol";

PremiumDIDRegistry premium = PremiumDIDRegistry(PREMIUM_ADDRESS);

// Register a human-readable DID name
premium.registerName(identity, "alice.lux");

// Verify identity (requires attestation)
premium.verifyIdentity(identity, proof);

Verified DID Benefits

Verified DID holders receive special treatment in the governance system:

Benefit	Description
Karma floor	Minimum 50 K (never fully decays)
Governance access	Required for proposal creation
Premium features	Human-readable DID names

Soulbound Identity

Identity tokens are soulbound (non-transferable) by default. They represent a verified on-chain identity tied to a specific address.

Key properties:

Non-transferable: Cannot be sent to another address
Revocable: The issuer or the holder can revoke
Composable: Other contracts can query identity status
Karma-linked: Verified DIDs get a Karma floor of 50 K

Integration with Governance

The identity system integrates directly with the Karma reputation system:

// KarmaMinter checks DID verification status
function rewardKarma(address recipient, bytes32 eventType, uint256 amount, bytes32 reason)
    external onlyRole(HOOK_ROLE);

// DID_VERIFICATION event: 100 K base, 1-year cooldown
// HUMANITY_PROOF event: 200 K base, 1-year cooldown

Verified DID holders enjoy a permanent Karma floor of 50 K, ensuring they always retain baseline voting power even after extended inactivity.

Events

The registry emits events for all state changes, enabling off-chain indexing:

event DIDAttributeChanged(
    address indexed identity,
    bytes32 name,
    bytes value,
    uint256 validTo,
    uint256 previousChange
);

event DIDDelegateChanged(
    address indexed identity,
    bytes32 delegateType,
    address delegate,
    uint256 validTo,
    uint256 previousChange
);

Identity (DID)