Title: Gluwacoin Standard
Author: Tae Lim Oh <[email protected]>
Type: Standard
Created: 2020-09-19
A standard interface for interoperable stablecoin tokens.
The following standard allows for the implementation of a standard API for interoperable stablecoin tokens compliant with the ERC20 token standard. This standard provides every standard ERC20 token method and, additionally, six custom methods for circulation control, ETHless transfer, and non-custodial exchange.
A standard interface to add any ERC-20 token to the Gluwa ecosystem to be re-used by other applications: from ETHless transfer and non-custodial exchange.
NOTE: Callers MUST handle false from returns (bool success).
Callers MUST NOT assume that false is never returned!
Creates amount tokens to the caller.
function mint(uint256 amount)Destroys amount tokens from the caller.
function burn(uint256 amount)Etherless Transfer Functions
Gluwacoin standard supports Etherless transfer for Gluwacoin users. Instead of paying gas to transfer Gluwacoin, a user pays a transfer fee in Gluwacoin to the contract owner.
A standard ERC20 function but with _fee, _nonce, and _sig as extra parameters.
_fee is a transfer fee amount in Gluwacoin, which the sender will pay for the transaction.
_sig is a signature created by signing the transfer information with the sender’s private key.
Anyone can initiate the transfer for the sender by calling the Etherless Transfer function
with the transfer information and the signature.
The caller will have to pay the gas for calling the function.
Transfers _value amount of tokens to address _to, and MUST fire the Transfer event.
The function SHOULD throw if the _from account balance does not have enough tokens to spend.
Note Transfers of 0 values MUST be treated as normal transfers and fire the Transfer event.
function transfer(address _from, address _to, uint256 _value, uint256 _fee, uint256 _nonce, bytes memory _sig) public returns (bool success)Non-custodial Exchange Function
Gluwacoin supports functions for non-custodial exchange use cases. Instead of trusting a 3rd party to hold Gluwacoins for an exchange, a user can request the 3rd party to lock Gluwacoins at the user’s account instead. The locked Gluwacoins are called a reserve and can only be released to the pre-designated receiver or unlocked back to the sender. Note that the exchange can happen not only between Gluwacoins but also with other cryptocurrencies. If a cryptocurrency supports features equivalent to the Gluwacoin non-custodial exchange functions, it is compatible. For instance, Bitcoin is compatible with Gluwacoin non-custodial exchange when utilizing a 2-to-3 multi-sig wallet.
Creates a reserve in _from address.
The amount of the reserve is _amount and each reserve has _nonce which is unique together with _from.
Assigns receiver's address _to and the validator's address _executor.
_expiryBlockNum specifies when the _from address can reclaim the reserve in case the reserve is unused.
_sig is a signature created by signing the transfer information with the _from address' private key.
function reserve(address _from, address _to, address _executor, uint256 _amount, uint256 _fee, uint256 _nonce, uint256 _expiryBlockNum, bytes memory _sig) public returns (bool success)Releases a fund reserved in _sender address.
The reserve is specified by _nonce.
The released fund is transferred to _to address.
Reserved for the _executor.
Note _to and _executor are pre-determined when the reserve was created.
function execute(address _sender, uint256 _nonce) public returns (bool success)Returns a fund reserved in _sender address.
The reserve is specified by _nonce.
The fund is transferred to _from address.
Reserved for the _from and _executor.
While _executor can call the function any time, _from can only call after _expiryBlockNum.
Note _from, _executor, and _expiryBlockNum are pre-determined when the reserve was created.
function reclaim(address _sender, uint256 _nonce) public returns (bool success)Returns the name of the token - e.g. "MyToken".
OPTIONAL - This method can be used to improve usability, but interfaces and other contracts MUST NOT expect these values to be present.
function name() constant returns (string name)Returns the symbol of the token. E.g. "HIX".
OPTIONAL - This method can be used to improve usability, but interfaces and other contracts MUST NOT expect these values to be present.
function symbol() constant returns (string symbol)Returns the number of decimals the token uses - e.g. 8, means to divide the token amount by 100000000 to get its user representation.
OPTIONAL - This method can be used to improve usability, but interfaces and other contracts MUST NOT expect these values to be present.
function decimals() constant returns (uint8 decimals)Returns the total token supply.
function totalSupply() constant returns (uint256 totalSupply)Returns the account balance of another account with address _owner.
function balanceOf(address _owner) constant returns (uint256 balance)Transfers _value amount of tokens to address _to, and MUST fire the Transfer event.
The function SHOULD throw if the _from account balance does not have enough tokens to spend.
Note Transfers of 0 values MUST be treated as normal transfers and fire the Transfer event.
function transfer(address _to, uint256 _value) returns (bool success)Transfers _value amount of tokens from address _from to address _to, and MUST fire the Transfer event.
The transferFrom method is used for a withdraw workflow, allowing contracts to transfer tokens on your behalf.
This can be used for example to allow a contract to transfer tokens on your behalf and/or to charge fees in sub-currencies.
The function SHOULD throw unless the _from account has deliberately authorized the sender of the message via some mechanism.
Note Transfers of 0 values MUST be treated as normal transfers and fire the Transfer event.
function transferFrom(address _from, address _to, uint256 _value) returns (bool success)Allows _spender to withdraw from your account multiple times, up to the _value amount. If this function is called again it overwrites the current allowance with _value.
NOTE: To prevent attack vectors like the one described here and discussed here,
clients SHOULD make sure to create user interfaces in such a way that they set the allowance first to 0 before setting it to another value for the same spender.
THOUGH The contract itself shouldn't enforce it, to allow backwards compatibility with contracts deployed before
function approve(address _spender, uint256 _value) returns (bool success)Returns the amount which _spender is still allowed to withdraw from _owner.
function allowance(address _owner, address _spender) constant returns (uint256 remaining)MUST trigger on any successful call to mint(address _to, uint256 _value).
event Mint(address indexed _mintTo, uint256 _value)
MUST trigger on any successful call to burn(address _to, uint256 _value).
event Burnt(uint256 _value)MUST trigger when tokens are transferred, including zero value transfers.
A token contract which creates new tokens SHOULD trigger a Transfer event with the _from address set to 0x0 when tokens are created.
event Transfer(address indexed _from, address indexed _to, uint256 _value)MUST trigger on any successful call to approve(address _spender, uint256 _value).
event Approval(address indexed _owner, address indexed _spender, uint256 _value)Gluwa provides standard implementations of Gluwacoin. You can implement it differently to have different trade-offs: from gas saving to improved security.
Historical links related to this standard:
- Orginial proposal from Vitalik Buterin: https://github.com/ethereum/wiki/wiki/Standardized_Contract_APIs/499c882f3ec123537fc2fccd57eaa29e6032fe4a
- Reddit discussion: https://www.reddit.com/r/ethereum/comments/3n8fkn/lets_talk_about_the_coin_standard/
- Original Issue #20: ethereum/EIPs#20
- Original whitepaper from Tae Oh: https://gluwacoin.com/whitepaper
- Original implementation from Gluwa, Inc.: https://github.com/Gluwa/Gluwacoin
Copyright and related rights waived via CC0.