centre-tokens

Fiat tokens on the CENTRE network.

Setup

Tests need node v8.0.0 or higher, as they depend on async/await functionality. Interacting with eth is very async-y so await makes it much easier to write tests. Depends on truffle and testrpc for testing.

install truffle: npm install -g truffle

install ganache-cli: npm install -g ganache-cli

install project npm dependencies: npm install

Testing

All tests are run with: npm run truffle-test

or run a specific file of tests with: npm run truffle-test -- [file]

to generate test coverage on all tests run: npm test

Contracts

The implementation uses 2 separate contracts - a proxy contract (FiatTokenProxy.sol)and an implementation contract(FiatToken.sol). This allows upgrading the contract, as a new implementation contact can be deployed and the Proxy updated to point to it.

FiatToken

The FiatToken offers a number of capabilities, which briefly are described below. There are more detailed design docs in the doc folder.

ERC20 compatible

The FiatToken implements the ERC20 interface.

Pausable

The entire contract can be frozen, in case a serious bug is found or there is a serious key compromise. No transfers can take place while the contract is paused. Access to the pause functionality is controlled by the pauser address.

Upgradable

A new implementation contract can be deployed, and the proxy contract will forward calls to the new contract. Access to the upgrade functionality is guarded by a proxyOwner address. Only the proxyOwner address can change the proxyOwner address.

Blacklist

The contract can blacklist certain addresses which will prevent those addresses from transferring or receiving tokens. Access to the blacklist functionality is controlled by the blacklister address.

Minting/Burning

Tokens can be minted or burned on demand. The contract supports having multiple minters simultaneously. There is a masterMinter address which controls the list of minters and how much each is allowed to mint. The mint allowance is similar to the ERC20 allowance - as each minter mints new tokens their allowance decreases. When it gets too low they will need the allowance increased again by the masterMinter.

Ownable

The contract has an Owner, who can change the owner, pauser, blacklister, or masterMinter addresses. The owner can not change the proxyOwner address.

OpenZeppelin

Contracts from OpenZeppelin version 1.10 are used where possible, with some modifications. These contracts are located in contracts/thirdparty/openzepplin. Ownable and Pausable have been modified. The other contacts are unmodified.

Ownable has been modified to:

1. Remove the renounceOwnership function and OwnershipdRenounced event.

Pausable has been modified to:

1. Add the pauser role, which controlls pause/unpause
2. Remove whenPaused/whenNotPaused modifiers on unpause/pause methods
3. Remove whenPaused as is is no longer used