Líf, a smart token for travel companies

Ethereum tokens have become very popular in the past months, They allow companies to issue assets for their platform and create markets where users can easily transfer value between themselves.

Since we started working on Winding Tree we knew that we needed to create a token to make our decentralized platform a reality. Not only because we need to transfer value, you can do that with Ethereum, but also to transfer data and execute functions between trusted contracts on our platform. This is why we decided to not only use a common ERC20 token but to also add a few more methods that allow us (and future developers) to build their own booking solutions using our token, called Líf.

Right know you can only transfer value on ERC20 tokens, what Líf tokens also need is the possibility to transfer more than just value, information too.

This is how the interface of the ERC20 looks:

pragma solidity ^0.4.11;

/**
 * @title ERC20 interface
 * @dev see https://github.com/ethereum/EIPs/issues/20
 */
contract ERC20 {
  uint256 public totalSupply;
  function balanceOf(address who) constant returns (uint256);
  function allowance(address owner, address spender) constant returns (uint256);
  function transferFrom(address from, address to, uint256 value);
  function approve(address spender, uint256 value);
  function transfer(address to, uint256 value);
  event Transfer(address indexed from, address indexed to, uint256 value);
  event Approval(address indexed owner, address indexed spender, uint256 value);
}

Líf tokens will have three additional methods, through which the token holder is be able to send value + data, log information, and/or execute a function on those transfers. This brings extra value and use cases to the token, allowing companies to design more complex and tailored applications on our platform.

Here is how the interface of our token would look:

pragma solidity ^0.4.11;

import 'zeppelin-solidity/contracts/token/ERC20.sol';

/**
 * @title Lif token interface
 */
contract LifInterface is ERC20 {
  uint public maxSupply;
  function approveData(address spender, uint value, bytes data, bool doCall);
  function transferData(address to, uint value, bytes data, bool doCall);
  function transferDataFrom(address from, address to, uint value, bytes data, bool doCall);
  event TransferData(address indexed from, address indexed to, uint256 value, bytes data);
  event ApprovalData(address indexed from, address indexed spender, uint256 value, bytes data);
}

This is what we are building on WT, a token that is ERC20 compatible with transfer, transferFrom and approve methods that will also receive a bytes parameter and execute a function in them, and not only execute functions, but also store data.

With the addition of these methods we allow for:

• Execution of booking on payment transaction, pay and register the booking on the same transaction.
• Send encrypted data between token holders.
• Log information on the blockchain, proof of existence.
• Distribute votes on our DAO every booking done.

We are currently working on these features and more, using zeppelin-solidity as a security framework. Security implementation is our highest priority when adding additional functions. Some of the functions include: approveData, transferData and transferDataFrom cannot have the token address as a receiver for example, because it would allow the access to internal function on it.

We believe that this is the next generation of token smart-contracts, and we intent to be the first to bring them to the Ethereum network.

On Medium