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Subdomain DAOS

A ENS Subdomain Decentralized Autonomous Organization (SDAO) is a DAO organized around a ENS domain name (e.g sismo.eth), which is owned by the DAO.

SDAO members are all owners of a subdomain (e.g ziki.sismo.eth). You can read about Sismo's specific SDAO here.

This repository publishes a set of smart contracts that can be used to kickstart a SDAO. Please feel free to create issues or to connect with its maintainer: @sismo_eth on twitter or contact at sismo.io

SDAO Contracts

The core contract SDaoRegistrar distributes subdomains to registrants. This contract must be set as the owner of the DAO domain name (e.g domain.eth). It contains the registration logic.

The organisation of the code is heavily inspired from the OpenZeppelin contracts packages. We built modular extensions extending contracts and presets. (see the ERC20 approach).

Extensions are for developers to choose what additional features or restrictions should be applied to their SDaoRegistrar.

A list of presets is also available. They are pre-configured contracts, ready to be deployed. Each of them uses a different set of extensions.

The code of this repository resolves around ENS, it is advised to be familiar with Ethereum Name Service notions.

Core contract: SDaoRegistrar (FCFS)

The contract allows first-come first-served (FCFS) registration of a subdomain, e.g. label.domain.eth through the register method. The ownership of the subdomain is given to the registrant. The newly created subdomain resolves to the registrant.

function register(string memory label)
    _register(_msgSender(), label);

The internal registration method _register is exposed internally for extensions of the SDaoRegistrar. Two hooks can be used: _beforeRegistration and _afterRegistration

function _register(address account, string memory label) internal {
    bytes32 labelHash = keccak256(bytes(label));
    _beforeRegistration(account, labelHash);
    // [...]: subdomain created, subdomain resolves towards accounts, subdomain owner is account
    _afterRegistration(account, labelHash);


    ENS ensAddr, // ENS Registry
    PublicResolver resolver, // Resolver to be used
    bytes32 node,    // nameHash('domain.eth')
    address owner    // owner of the registrar

The node corresponds to the namehash of the domain of the SDAO, e.g. domain.eth.

Interface and Implementation

See contracts/subdomain-dao/ISDaoRegistrar.sol and contracts/subdomain-dao/SDaoRegistrar.sol for the exact interface and implementation.


An extension is an abstract contract which inherits the SDaoRegistrar core contract.

It may add other public methods for registration using the internal registration method or/and implements the beforeRegistration and afterRegistration hooks.

extensions are easy to read: /contracts/subdomain-dao/extensions/*.sol

SDaoRegistrarReserved Extension

function _beforeRegistration(address account, bytes32 labelHash)
    super._beforeRegistration(account, labelHash);

    if (block.timestamp - DAO_BIRTH_DATE <= _reservationDuration) {
      address dotEthSubdomainOwner = ENS_REGISTRY.owner(
        keccak256(abi.encodePacked(ETH_NODE, labelHash))
        dotEthSubdomainOwner == address(0x0) ||
          dotEthSubdomainOwner == _msgSender(),

A reservation period is introduced during which registration of a subdomain subdomain.domain.eth is blocked if the related subdomain.eth is owned by someone else than the registrant. The reservation period can be updated by the owner of the contract.

See contracts/subdomain-dao/extensions/SDaoRegistrarReserved.sol for the implementation.

SDaoRegistrarLimited Extension

function _beforeRegistration(address account, bytes32 labelHash)
    super._beforeRegistration(account, labelHash);

      _counter < _registrationLimit,
function _afterRegistration(address account, bytes32 labelHash)
    super._afterRegistration(account, labelHash);

    _counter += 1;

A counter for the number of registered subdomains and a registration limit number are added. If the counter reaches the registration limit, registration is blocked. The registration limit can be updated by the owner of the contract.

See contracts/subdomain-dao/extensions/SDaoRegistrarLimited.sol for the implementation.

SDaoRegistrarERC721Generator Extension

function _afterRegistration(address account, bytes32 labelHash)
    super._afterRegistration(account, labelHash);

    bytes32 childNode = keccak256(abi.encodePacked(ROOT_NODE, labelHash));
    ERC721_TOKEN.mintTo(account, uint256(childNode));

An ERC721 is minted and the registration is blocked if the balance of the registrant is not zero. See contracts/subdomain-dao/extensions/SDaoRegistrarERC721Generator.sol for the implementation.

SDaoRegistrarERC1155Generator Extension

function _afterRegistration(address account, bytes32 labelHash)
    super._afterRegistration(account, labelHash);

    (uint256 id, bytes memory data) = _getToken(account, labelHash);

    ERC1155_MINTER.mint(account, id, 1, data);

An ERC1155 token is minted for the registrant after each registration. The ERC1155 token ID and data are left free to be implemented by the developer. The registration is blocked if the balance of the registrant is not zero, based on a balanceOf method to be implemented by the developer. See contracts/subdomain-dao/extensions/SDaoRegistrarERC1155Generator.sol for the implementation.

SDaoRegistrarCodeAccessible Extension

function registerWithAccessCode(
    string memory label,
    address recipient,
    bytes memory accessCode
  ) external override {
    // [...]

      digest.recover(accessCode) == _codeSigner,
    // [...]

A new public method of registration registerWithAccessCode is added. It allows to register a subdomain if a valid access code is given.

An access code is a signed message according to the EIP712 specification. The message contains domain specific information set at the deployment of the contract and the data of the message. The data contains the recipient address, which will receive the subdomain, and a number called group ID.

The message must be signed by a specific code signer address in order to be valid. The code signer value is managed by the owner of the contract. The group ID is retrieved using an internal method that needs to be implemented in the final contract.

An access code can only be consumed once.

See contracts/subdomain-dao/extensions/SDaoRegistrarCodeAccessible.sol for the implementation.

SDaoRegistrarClaimable Extension

function claim(string memory label, address account) public override {
    bytes32 labelHash = keccak256(bytes(label));
    address bookingAddress = ENS_LABEL_BOOKER.getBooking(labelHash);
      bookingAddress != address(0),
      bookingAddress == _msgSender() || owner() == _msgSender(),

    _register(account, label);


An address of an ENS Label Booker is added. The latter manages a mapping of booking formed by a link between a subdomain and a booking address.

A new public method of registration claim is added. It allows to register a subdomain if the sender of the message is the booking address associated to the subdomain.

The FCFS served registration is blocked if the subdomain is already booked.

See contracts/subdomain-dao/extensions/SDaoRegistrarClaimable.sol and contracts/ens-label-booker/ENSLabelBooker.sol for the implementation of the extension and the Label Booker contracts.


A preset is an SDAO Registrar contract extended with a set of extensions. It may be considered as ready to use contracts or examples of the extensions usage.

  • Limited Reserved ERC1155 Preset
    • hardhat task deploy-sdao-preset-erc1155)
    • implements SDaoRegistrarLimited, SDaoRegistrarReserved and SDaoRegistrarERC1155Generator extensions.
  • Limited Reserved ERC721 Preset
    • hardhat task: deploy-sdao-preset-erc721
    • implements SDaoRegistrarLimited, SDaoRegistrarReserved and SDaoRegistrarERC721Generator extensions.
  • Code Accessible Preset
    • hardhat task: deploy-sdao-preset-code-accessible
    • implements SDaoRegistrarCodeAccessible extension
  • Claimable Preset
    • hardhat task: deploy-sdao-preset-claimable
    • implements SDaoRegistrarClaimable extension

See contracts/subdomain-dao/presets/*.sol for the implementations.

Hardhat scripts

Note: Most of the scripts are used for development purposes. Deployment scripts for the various presets are available but it is strongly advised to understand them before using them.


const deployedENS: DeployedEns = await HRE.run('deploy-ens-full', {sDao: true, log: true});
// with 
export type DeployedEns = {
  ensDeployer: ENSDeployer;
  registry: ENSRegistry;
  registrar: EthRegistrar;
  reverseRegistrar: ReverseRegistrar;
  publicResolver: PublicResolver;

Deploys a suite of ENS contracts. The deployed .eth Registrar is simplified in order to allow direct registration instead of the usual two steps registration process.

The boolean flag sDao allows to additionally deploy a SDAO Registrar.

See tasks/deploy-ens-full.ts for the script and the full list of parameters.


Deploys a Label Booker contract.

The name of the targeted domain is given as parameter, i.e. <name>.eth.

See tasks/deploy-label-booker.ts for the script and the full list of parameters.


NPM scripts

npm install

Install the dependencies.

npm compile

Compile the smart contracts and generate the associated TypeScript types.

npm test

Launch all the tests.

Individual scripts are available for each test suite.

The contracts/test-utils repository contains various helpful contracts for the tests, in particular the ENSDeployer that can be used in order to redeploy a suite of ENS contracts with a modified Registrar.


The code of this repository is released under the MIT License.

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