Gateway

The Gateway contract is designed to interact with the Factory (the factory uses a Ownable mechanics to allow deployments of ONCHAINIDs). For a local usage or a custom implementation, the Factory can be used alone, but some companies managing many identities across multiples chains may want to use the Factory and the Gateway to have ONCHAINIDs deployed with identical addresses.

Note that this could be implemented using Oracles and decentralized networks. However, we think fully decentralized and user-owned identities should be deployed as standalone contracts without a Factory and/or Gateway.

Why a Gateway?

The Factory allows to deploy ONCHAINIDs using the same addresses across multiple chains. However, we cannot allow anyone to deploy an ONCHAINID using that factory (otherwise a user would be able to use salts that should be reserved for other identities).

The Gateway contract is designed to allow users to deploy ONCHAINIDs using their wallet address as a salt, meaning they can deploy their own ONCHAINID on any chain and have the same address. If a user loses access to their wallet, they would never be able to deploy their ONCHAINID again with the same address on other chains. We therefore allow a user to deploy their ONCHAINID using a custom salt (e.g. their lost wallet address) so that they can still have the same address for their ONCHAINID. As a protection mechanism, we require the user to provide a message signed by a Gateway trusted address.

Some implementation of the protocol also base identities on a master chain. Other chains have Gateways that require signatures to deploy any ONCHAINIDs.

How to use the Gateway?

danger

Allowing a user to deploy an ONCHAINID using a custom salt is a security risk. The Gateway Operator should always make sure to properly verify the identity of the user before signing the approval message. When using approval signed by third parties, they should validate the signer performs these verification.

Once a user obtains their approval signature, they can deploy their ONCHAINID on any chain that have a Gateway trusting the signer.

deployIdentityWithSalt(address identityOwner, string memory salt, uint256 signatureExpiry, bytes calldata signature);

await gateway.deployIdentityWithSalt(
  managementKeyAddress,
  'customSalt',
  signatureExpiry,
  signature,
);

To deploy an identity using the wallet a the salt, use the deployIdentityForWallet(address identityOwner) method.

To deploy an identity using a custom salt and a specific list of management keys (other that the identity owner address), use the function deployIdentityWithSaltAndManagementKeys(address identityOwner, string memory salt, bytes32[] calldata managementKeys, uint256 signatureExpiry, bytes calldata signature) method. Note that the identityOwner address won't be added as a management key, only the keys specified in the managementKeys array will.

Specifications

Approval signature message content

The approval is a signature of the following message:

import "@openzeppelin/contracts/utils/cryptography/ECDSA.sol";

using ECDSA for bytes32;

keccak256(
    abi.encode(
        "Authorize ONCHAINID deployment",
        managementKeyAddress,
        salt,
        signatureExpiry,
    )
).toEthSignedMessageHash();

toEthSignedMessageHash is a function from OpenZeppelin's ECDSA library, it prefixes the message.

const digest = ethers.utils.keccak256(
    ethers.utils.defaultAbiCoder.encode(
        ['string', 'address', 'string', 'uint256'],
        [
          'Authorize ONCHAINID deployment',
          managementKeyAddress,
          'saltToUse',
          BigNumber.from(new Date().getTime()).div(1000).add(365 * 24 * 60 * 60), // expiry solidity timestamp (in seconds)
        ],
    ),
);
const signature = await carolWallet.signMessage(
    ethers.utils.arrayify(
        digest,
    ),
);

Setting the expiry to 0 will make the signature valid until explicitly revoked.

For signatures used by the deployIdentityWithSaltAndManagementKeys method, the content is extendend with the list of management keys to use:

import "@openzeppelin/contracts/utils/cryptography/ECDSA.sol";

using ECDSA for bytes32;

keccak256(
    abi.encode(
        "Authorize ONCHAINID deployment",
        identityOwner,
        salt,
        managementKeys,
        signatureExpiry,
    )
).toEthSignedMessageHash();

const digest = ethers.utils.keccak256(
    ethers.utils.defaultAbiCoder.encode(
        ['string', 'address', 'string', 'bytes32[]', 'uint256'],
        [
          'Authorize ONCHAINID deployment',
          managementKeyAddress,
          'saltToUse',
          [
            ethers.utils.defaultAbiCoder.encode(['address'], [key1]),
            ethers.utils.defaultAbiCoder.encode(['address'], [key2]),
          ],
          BigNumber.from(new Date().getTime()).div(1000).add(365 * 24 * 60 * 60), // expiry solidity timestamp (in seconds)
        ],
    ),
);
const signature = await carolWallet.signMessage(
    ethers.utils.arrayify(
        digest,
    ),
);