Ethereum Access Token

Implementation of EIP-712 for signed access token verification.

Tokens authorise a user to perform specific on-chain interactions as determined by the token issuer.

Tokens are in the form:

{
  "expiry": <unix_seconds-uint256>,
  "functionCall": {
    "functionSignature": <solidity_function_sig_hex-string>,
    "target": <contract_address_of_tx_target-string>,
    "caller": <user_address_of_tx_caller-string>,
    "parameters": <hexadecimal_representation_of_parameters-string>
  }
}

Tokens are signed according to EIP-712 using signTypedData and are verified on-chain through the Auth.sol contract verify function.

Parameters are abi-encoded similarly to how solidity does it. This is to ensure that we are signing the data that we expect to see during the transaction. Due to the entrypoint transaction containing signature-relevant parts, these parameters will be excluding all parts relating to the signature and expiry of the AuthToken. Example:

If the function to be called is the following:

function transfer(address recipient, uint256 amount) public;

then the version that requires authorisation is the following:

function transfer(uint8 v, bytes32 r, bytes32 s, uint256 expiry, address recipient, uint256 amount) public requiresAuth;

and parameters to the function are the original address recipient and uint256 amount which will be encoded as follows: abi.encodeWithSignature('transfer(address,uint256)', recipient, amount)

Usage

Pre Requisites

Before running any command, you need to create a .env file and set a BIP-39 compatible mnemonic as an environment variable. Follow the example in .env.example. If you don't already have a mnemonic, use this website to generate one.

Then, proceed with installing dependencies:

yarn install

Compile

Compile the smart contracts with Hardhat:

$ yarn compile

TypeChain

Compile the smart contracts and generate TypeChain artifacts:

$ yarn typechain

Lint Solidity

Lint the Solidity code:

$ yarn lint:sol

Lint TypeScript

Lint the TypeScript code:

$ yarn lint:ts

Test

Run the Mocha tests:

$ yarn test

Coverage

Generate the code coverage report:

$ yarn coverage

Report Gas

See the gas usage per unit test and average gas per method call:

$ REPORT_GAS=true yarn test

Clean

Delete the smart contract artifacts, the coverage reports and the Hardhat cache:

$ yarn clean

Deploy

Deploy the contracts to Hardhat Network:

$ yarn deploy --greeting "Bonjour, le monde!"

Syntax Highlighting

If you use VSCode, you can enjoy syntax highlighting for your Solidity code via the vscode-solidity extension. The recommended approach to set the compiler version is to add the following fields to your VSCode user settings:

{
  "solidity.compileUsingRemoteVersion": "v0.8.4+commit.c7e474f2",
  "solidity.defaultCompiler": "remote"
}

Where of course v0.8.4+commit.c7e474f2 can be replaced with any other version.