User Privacy

User Privacy Protection

• Hidden Addresses: Protocol interaction is based on mapping wallet addresses to UserIds. Wallet addresses will not be exposed in event logs, using UserId instead to reduce on-chain associativity.

• SIWE Permission Verification: Reading important data requires a wallet signature SIWE token, and the contract does not provide address parameter access functions.

• Relay Proxy Meta Transactions: The mainnet will fully adopt the ERC2771 standard for relay proxy meta transactions + relay contract Forwarder interaction, without direct interaction with the contract, and on-chain behavior is not visible.

• Privacy Payments: Supports payments via privacy tokens and Zcash masked addresses authorized by EIP-712 signatures, hiding user payment information. Please see the privacy-token section.

UserManager Contract

abstract contract IdentitySalt {
    error EmptyIdentitySalt();
    // Master secret for key derivation
    bytes32 private _identitySalt;

    constructor(bytes memory pers_) {
        // Initialize the cryptographically secure master secret for identity derivation
        if (_identitySalt == bytes32(0)) {
            _identitySalt = bytes32(Sapphire.randomBytes(32, pers_));
        }
    }

    /**
     * @dev Core logic: convert address to irreversible privacy hash using Sapphire KDF
     */
    function _getUserId(address user_) internal view returns (bytes32) {
        if (user_ == address(0)) return bytes32(0);

        if (_identitySalt == bytes32(0)) revert EmptyIdentitySalt();

        // Convert address to bytes32 to use as salt/context for derivation
        bytes32 contextSalt = bytes32(uint256(uint160(user_)));

        // Use Sapphire's native HKDF-based symmetric key derivation
        // This is more secure than simple keccak256 hashing
        return
            Sapphire.deriveSymmetricKey(
                Sapphire.Curve25519PublicKey.wrap(contextSalt),
                Sapphire.Curve25519SecretKey.wrap(_identitySalt)
            );
    }

    /**
     * @dev Base on SIWE contract
     * @param siweToken_ SIWE token
     * @return user_id User ID
    */
    function myUserId(bytes memory siweToken_) public view returns (bytes32) {
        address sender = msg.sender;
        if (sender == address(0)) {
            // Use SiweContext get sender
            sender = _msgSenderSiwe(SIWE_AUTH, siweToken_);
        }
        _checkInBlacklist(sender);

        return _getUserId(sender);
    }
}

Testnet Strategy: The testnet retains direct interaction for ease of debugging and verification; for the mainnet, it is recommended to use proxy interaction to enhance privacy.