​
Welcome

This guide will get you up to speed on all the concepts you need to know to develop your first confidential dapp. Throughout this guide, we will be using several examples, the most common one being a confidential token. A confidential token behaves similarly to a regular ERC20 token, but the balances of the holders, and transfer amounts are hidden from the public.

Here is the full code of a simple confidential token contract:

// SPDX-License-Identifier: MIT
pragma solidity ^0.8;

import {euint256, ebool, e} from "@inco/lightning/Lib.sol";

contract SimpleConfidentialToken {
    using e for *;

    mapping(address => euint256) public balanceOf;

    constructor() {
        balanceOf[msg.sender] = uint256(1000 * 1e9).asEuint256();
    }

    function transfer(
        address to,
        bytes memory valueInput
    ) external returns (ebool) {
        euint256 value = valueInput.newEuint256(msg.sender);
        return _transfer(to, value);
    }

    function transfer(
        address to,
        euint256 value
    ) public returns (ebool success) {
        require(
            msg.sender.isAllowed(value),
            "SimpleConfidentialToken: unauthorized value handle access"
        );

        return _transfer(to, value);
    }

    function _transfer(
        address to,
        euint256 value
    ) external returns (ebool success) {
        success = balanceOf[msg.sender].ge(value);
        euint256 transferredValue = success.select(
            value,
            uint256(0).asEuint256()
        );

        euint256 senderNewBalance = balanceOf[msg.sender].sub(transferredValue);
        euint256 receiverNewBalance = balanceOf[to].add(transferredValue);

        balanceOf[msg.sender] = senderNewBalance;
        balanceOf[to] = receiverNewBalance;

        senderNewBalance.allow(msg.sender);
        receiverNewBalance.allow(to);
        senderNewBalance.allowThis();
        receiverNewBalance.allowThis();
    }
}

Continue this guide to understand how this code works and its concepts.

Was this page helpful?