Bancor Protocol™ is a standard for the creation of Smart Tokens™, cryptocurrencies with built-in convertibility directly through their smart contracts. Bancor utilizes an innovative token "Connector" method to enable formulaic price-calculation and continuous liquidity to/from all tokens in the Bancor Network™, without needing to match two parties in an exchange. Smart Tokens™ interconnect to form token liquidity networks, allowing user-generated cryptocurrencies to thrive. For more information, visit the website and read the Bancor Protocol™ Whitepaper.

The Bancor protocol represents the first technological solution for the classic problem in economics known as the “Double Coincidence of Wants”, in the domain of asset exchange. For barter, the coincidence of wants problem was solved through money. For money, exchanges still rely on labor, via bid/ask orders and trade between external agents, to make markets and supply liquidity.

Through the use of smart-contracts, Smart Tokens can be created that hold one or more other tokens as connectors. Tokens may represent existing national currencies or other types of assets. By using a connector token model and algorithmically-calculated conversion rates, the Bancor Protocol creates a new type of ecosystem for asset exchange, with no central control. This decentralized hierarchical monetary system lays the foundation for an autonomous decentralized global exchange with numerous and substantial advantages.

Bancor is a work in progress. Make sure you understand the risks before using it.

Bancor protocol is implemented using multiple contracts. The main ones are SmartToken and BancorConverter. BancorConverter implements the token converter standard and is responsible for converting between a token and its connectors. SmartToken represents a converter aware ERC-20 compliant token.

Those will allow creating a Bancor compliant token while keeping dependencies at a minimum. In addition, it allows an owning contract to extend its functionality by giving the owner full control.

First and foremost, a Smart Token is also an ERC-20 compliant token. As such, it implements both the standard token methods and the standard token events.

Note that these methods can only be executed by the token owner.

issue

function issue(address _to, uint256 _amount)

Increases the token supply and sends the new tokens to an account.


destroy

function destroy(address _from, uint256 _amount)

Removes tokens from an account and decreases the token supply.


disableTransfers

function disableTransfers(bool _disable)

Disables transfer/transferFrom functionality.

NewSmartToken

event NewSmartToken(address _token)

Triggered when a smart token is deployed.


Issuance

event Issuance(uint256 _amount)

Triggered when the total supply is increased.


Destruction

event Destruction(uint256 _amount)

Triggered when the total supply is decreased.

The following section describes standard functions a bancor converter can implement.

Those will allow dapps and wallets to buy and sell the token.

The most important here is convert.

First and foremost, a Bancor Converter is also an EIP-228 compliant converter. As such, it implements both the standard converter methods and the standard converter events.

connectorTokenCount

function connectorTokenCount() public constant returns (uint16 count)

Gets the number of connector tokens defined for the token.


connectorTokens

function connectorTokens() public constant returns (address[] connectorTokens)

Gets an array of the connector token contract addresses.


connectors

function connectors(address _connectorToken) public constant

Gets the connector token details.


convert

function convert(address _fromToken, address _toToken, uint256 _amount, uint256 _minReturn)

converts a specific amount of _fromToken to _toToken The conversion will only take place if it returns a value greater or equal to _minReturn.

Conversion

event Conversion(address indexed _fromToken, address indexed _toToken, address indexed _trader, uint256 _amount, uint256 _return, uint256 _currentPriceN, uint256 _currentPriceD);

Triggered when a conversion between one of the convertible tokens takes place.

Tests are included and can be run using truffle.

• Node.js v7.6.0+
• truffle v3.2.2+
• testrpc v3.0.5+

To run the test, execute the following commands from the project's root folder -

• npm run testrpc
• npm test

• Yudi Levi
• Ilana Pinhas
• Barak Manos
• Martin Holst Swende

Bancor Protocol is open source and distributed under the Apache License v2.0