Add ERC: Decentralized Identity Verification (DID)

erc-64.md

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+---
+eip: xx
+title: Decentralized Identity Verification (DID) Standard
+description: A standard for decentralized identity verification on the Ethereum blockchain.
+author: Anushka Yadav <64anushka@gmail.com>
+discussions-to: https://ethereum-magicians.org/t/discussion-on-decentralized-identity-verification-did-standard/20392
+status: Draft
+type: Standards Track
+category: ERC
+created: 2024-07-02
+---
+
+## Abstract
+
+This proposal introduces a standard for decentralized identity verification (DID) on the Ethereum blockchain. The standard aims to provide a secure, privacy-preserving method for identity verification that can be used by decentralized applications (dApps).
+
+## Motivation
+
+Centralized identity verification methods are often cumbersome, prone to data breaches, and do not give users control over their identity data. A decentralized identity verification standard will allow users to maintain control over their identity information while ensuring security and privacy.
+
+## Specification
+
+The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 and RFC 8174.
+
+### Interface
+
+```solidity
+pragma solidity ^0.8.0;
+
+interface IDecentralizedIdentity {
+    // Struct to represent an identity
+    struct Identity {
+        address userAddress; // Ethereum address of the user
+        bytes32 identityHash; // Hash of the identity data
+        bytes32[2] verificationHashes; // Hashes used for verifying identity
+        bool isVerified; // Indicates if the identity is verified
+        uint256 timestamp; // Timestamp of identity creation
+    }
+
+    // Event emitted when a new identity is created
+    event IdentityCreated(address indexed userAddress, bytes32 identityHash, uint256 timestamp);
+
+    // Event emitted when an identity is verified
+    event IdentityVerified(address indexed userAddress, bytes32[2] verificationHashes, uint256 timestamp);
+
+    // Event emitted when an identity is revoked
+    event IdentityRevoked(address indexed userAddress, uint256 timestamp);
+
+    // Function to create a new decentralized identity for the caller.
+    // Parameters:
+    // - identityHash: Hash of the identity data.
+    function createIdentity(bytes32 identityHash) external;
+
+    // Function to verify the decentralized identity for the caller.
+    // Parameters:
+    // - verificationHashes: Hashes used for verifying the identity.
+    function verifyIdentity(bytes32[2] calldata verificationHashes) external;
+
+    // Function to revoke the decentralized identity for the caller.
+    function revokeIdentity() external;
+
+    // Function to retrieve the decentralized identity for a given user address
+    // Parameters:
+    // - userAddress Ethereum address of the user.
+    // Returns:
+    // identity The decentralized identity struct.
+    function getIdentity(address userAddress) external view returns (Identity memory);
+}
+
+```
+
+## Rationale
+
+The design leverages cryptographic hashes to represent identity information, ensuring that sensitive data is not stored directly on the blockchain. The use of verification hashes allows for flexible identity verification mechanisms, and the inclusion of events ensures transparency and traceability.
+
+## Reference Implementation
+
+```solidity
+pragma solidity ^0.8.0;
+
+import "./IDecentralizedIdentity.sol";
+
+contract DecentralizedIdentity is IDecentralizedIdentity {
+    // Mapping to store identities by user address
+    mapping(address => Identity) private identities;
+
+    // Function to create a new decentralized identity for the caller.
+    // Parameters:
+    // - identityHash Hash of the identity data.
+    function createIdentity(bytes32 identityHash) external override {
+        // Ensure identity does not already exist
+        require(identities[msg.sender].userAddress == address(0), "Identity already exists");
+
+        // Create the identity for the caller
+        identities[msg.sender] = Identity({
+            userAddress: msg.sender,
+            identityHash: identityHash,
+            verificationHashes: [bytes32(0), bytes32(0)], // Initialize with empty hashes
+            isVerified: false,
+            timestamp: block.timestamp
+        });
+
+        // Emit event for the creation of a new identity
+        emit IdentityCreated(msg.sender, identityHash, block.timestamp);
+    }
+
+    // Function to verify the decentralized identity for the caller.
+    // Parameters:
+    // - verificationHashes: Hashes used for verifying the identity.
+    function verifyIdentity(bytes32[2] calldata verificationHashes) external override {
+        // Ensure identity exists
+        require(identities[msg.sender].userAddress != address(0), "Identity does not exist");
+
+        // Update verification hashes and mark identity as verified
+        identities[msg.sender].verificationHashes = verificationHashes;
+        identities[msg.sender].isVerified = true;
+
+        // Emit event for the verification of identity
+        emit IdentityVerified(msg.sender, verificationHashes, block.timestamp);
+    }
+
+    // Function to revoke the decentralized identity for the caller.
+    function revokeIdentity() external override {
+        // Ensure identity exists
+        require(identities[msg.sender].userAddress != address(0), "Identity does not exist");
+
+        // Mark identity as not verified
+        identities[msg.sender].isVerified = false;
+
+        // Emit event for the revocation of identity
+        emit IdentityRevoked(msg.sender, block.timestamp);
+    }
+
+    // Function to retrieve the decentralized identity for a given user address
+    // Parameters:
+    // - userAddress Ethereum address of the user.
+    // Returns:
+    // identity The decentralized identity struct.
+    function getIdentity(address userAddress) external view override returns (Identity memory) {
+        return identities[userAddress];
+    }
+}
+```
+
+## Security Considerations
+
+**Secure Hashing**: Ensure that identity and verification hashes are generated using a secure hashing algorithm to prevent collisions and ensure the integrity of the identity data.
+
+**User Control**: Users have control over their identity data, which reduces the risk of unauthorized access and ensures privacy.
+
+## Copyright
+
+Copyright and related rights waived via [CC0](../LICENSE.md).