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quantstamp ico contract
pragma solidity ^0.4.15;
/**
* @title SafeMath
* @dev Math operations with safety checks that throw on error
*/
library SafeMath {
function mul(uint256 a, uint256 b) internal constant returns (uint256) {
uint256 c = a * b;
assert(a == 0 || c / a == b);
return c;
}
function div(uint256 a, uint256 b) internal constant returns (uint256) {
// assert(b > 0); // Solidity automatically throws when dividing by 0
uint256 c = a / b;
// assert(a == b * c + a % b); // There is no case in which this doesn't hold
return c;
}
function sub(uint256 a, uint256 b) internal constant returns (uint256) {
assert(b <= a);
return a - b;
}
function add(uint256 a, uint256 b) internal constant returns (uint256) {
uint256 c = a + b;
assert(c >= a);
return c;
}
}
/**
* @title Ownable
* @dev The Ownable contract has an owner address, and provides basic authorization control
* functions, this simplifies the implementation of "user permissions".
*/
contract Ownable {
address public owner;
event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);
/**
* @dev The Ownable constructor sets the original `owner` of the contract to the sender
* account.
*/
function Ownable() {
owner = msg.sender;
}
/**
* @dev Throws if called by any account other than the owner.
*/
modifier onlyOwner() {
require(msg.sender == owner);
_;
}
/**
* @dev Allows the current owner to transfer control of the contract to a newOwner.
* @param newOwner The address to transfer ownership to.
*/
function transferOwnership(address newOwner) onlyOwner public {
require(newOwner != address(0));
OwnershipTransferred(owner, newOwner);
owner = newOwner;
}
}
/**
* @title Pausable
* @dev Base contract which allows children to implement an emergency stop mechanism.
*/
contract Pausable is Ownable {
event Pause();
event Unpause();
bool public paused = false;
/**
* @dev Modifier to make a function callable only when the contract is not paused.
*/
modifier whenNotPaused() {
require(!paused);
_;
}
/**
* @dev Modifier to make a function callable only when the contract is paused.
*/
modifier whenPaused() {
require(paused);
_;
}
/**
* @dev called by the owner to pause, triggers stopped state
*/
function pause() onlyOwner whenNotPaused public {
paused = true;
Pause();
}
/**
* @dev called by the owner to unpause, returns to normal state
*/
function unpause() onlyOwner whenPaused public {
paused = false;
Unpause();
}
}
/**
* @title ERC20Basic
* @dev Simpler version of ERC20 interface
* @dev see https://github.com/ethereum/EIPs/issues/179
*/
contract ERC20Basic {
uint256 public totalSupply;
function balanceOf(address who) public constant returns (uint256);
function transfer(address to, uint256 value) public returns (bool);
event Transfer(address indexed from, address indexed to, uint256 value);
}
/**
* @title ERC20 interface
* @dev see https://github.com/ethereum/EIPs/issues/20
*/
contract ERC20 is ERC20Basic {
function allowance(address owner, address spender) public constant returns (uint256);
function transferFrom(address from, address to, uint256 value) public returns (bool);
function approve(address spender, uint256 value) public returns (bool);
event Approval(address indexed owner, address indexed spender, uint256 value);
}
/**
* @title Basic token
* @dev Basic version of StandardToken, with no allowances.
*/
contract BasicToken is ERC20Basic {
using SafeMath for uint256;
mapping(address => uint256) balances;
/**
* @dev transfer token for a specified address
* @param _to The address to transfer to.
* @param _value The amount to be transferred.
*/
function transfer(address _to, uint256 _value) public returns (bool) {
require(_to != address(0));
// SafeMath.sub will throw if there is not enough balance.
balances[msg.sender] = balances[msg.sender].sub(_value);
balances[_to] = balances[_to].add(_value);
Transfer(msg.sender, _to, _value);
return true;
}
/**
* @dev Gets the balance of the specified address.
* @param _owner The address to query the the balance of.
* @return An uint256 representing the amount owned by the passed address.
*/
function balanceOf(address _owner) public constant returns (uint256 balance) {
return balances[_owner];
}
}
/**
* @title Standard ERC20 token
*
* @dev Implementation of the basic standard token.
* @dev https://github.com/ethereum/EIPs/issues/20
* @dev Based on code by FirstBlood: https://github.com/Firstbloodio/token/blob/master/smart_contract/FirstBloodToken.sol
*/
contract StandardToken is ERC20, BasicToken {
mapping (address => mapping (address => uint256)) allowed;
/**
* @dev Transfer tokens from one address to another
* @param _from address The address which you want to send tokens from
* @param _to address The address which you want to transfer to
* @param _value uint256 the amount of tokens to be transferred
*/
function transferFrom(address _from, address _to, uint256 _value) public returns (bool) {
require(_to != address(0));
uint256 _allowance = allowed[_from][msg.sender];
// Check is not needed because sub(_allowance, _value) will already throw if this condition is not met
// require (_value <= _allowance);
balances[_from] = balances[_from].sub(_value);
balances[_to] = balances[_to].add(_value);
allowed[_from][msg.sender] = _allowance.sub(_value);
Transfer(_from, _to, _value);
return true;
}
/**
* @dev Approve the passed address to spend the specified amount of tokens on behalf of msg.sender.
*
* Beware that changing an allowance with this method brings the risk that someone may use both the old
* and the new allowance by unfortunate transaction ordering. One possible solution to mitigate this
* race condition is to first reduce the spender's allowance to 0 and set the desired value afterwards:
* https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
* @param _spender The address which will spend the funds.
* @param _value The amount of tokens to be spent.
*/
function approve(address _spender, uint256 _value) public returns (bool) {
allowed[msg.sender][_spender] = _value;
Approval(msg.sender, _spender, _value);
return true;
}
/**
* @dev Function to check the amount of tokens that an owner allowed to a spender.
* @param _owner address The address which owns the funds.
* @param _spender address The address which will spend the funds.
* @return A uint256 specifying the amount of tokens still available for the spender.
*/
function allowance(address _owner, address _spender) public constant returns (uint256 remaining) {
return allowed[_owner][_spender];
}
/**
* approve should be called when allowed[_spender] == 0. To increment
* allowed value is better to use this function to avoid 2 calls (and wait until
* the first transaction is mined)
* From MonolithDAO Token.sol
*/
function increaseApproval (address _spender, uint _addedValue)
returns (bool success) {
allowed[msg.sender][_spender] = allowed[msg.sender][_spender].add(_addedValue);
Approval(msg.sender, _spender, allowed[msg.sender][_spender]);
return true;
}
function decreaseApproval (address _spender, uint _subtractedValue)
returns (bool success) {
uint oldValue = allowed[msg.sender][_spender];
if (_subtractedValue > oldValue) {
allowed[msg.sender][_spender] = 0;
} else {
allowed[msg.sender][_spender] = oldValue.sub(_subtractedValue);
}
Approval(msg.sender, _spender, allowed[msg.sender][_spender]);
return true;
}
}
/**
* @title Burnable Token
* @dev Token that can be irreversibly burned (destroyed).
*/
contract BurnableToken is StandardToken {
event Burn(address indexed burner, uint256 value);
/**
* @dev Burns a specific amount of tokens.
* @param _value The amount of token to be burned.
*/
function burn(uint256 _value) public {
require(_value > 0);
address burner = msg.sender;
balances[burner] = balances[burner].sub(_value);
totalSupply = totalSupply.sub(_value);
Burn(burner, _value);
}
}
// Quantstamp Technologies Inc. (info@quantstamp.com)
/**
* The Quantstamp token (QSP) has a fixed supply and restricts the ability
* to transfer tokens until the owner has called the enableTransfer()
* function.
*
* The owner can associate the token with a token sale contract. In that
* case, the token balance is moved to the token sale contract, which
* in turn can transfer its tokens to contributors to the sale.
*/
contract QuantstampToken is StandardToken, BurnableToken, Ownable {
// Constants
string public constant name = "Quantstamp Token";
string public constant symbol = "QSP";
uint8 public constant decimals = 18;
uint256 public constant INITIAL_SUPPLY = 1000000000 * (10 ** uint256(decimals));
uint256 public constant CROWDSALE_ALLOWANCE = 650000000 * (10 ** uint256(decimals));
uint256 public constant ADMIN_ALLOWANCE = 350000000 * (10 ** uint256(decimals));
// Properties
uint256 public crowdSaleAllowance; // the number of tokens available for crowdsales
uint256 public adminAllowance; // the number of tokens available for the administrator
address public crowdSaleAddr; // the address of a crowdsale currently selling this token
address public adminAddr; // the address of the token admin account
bool public transferEnabled = false; // indicates if transferring tokens is enabled or not
// Modifiers
modifier onlyWhenTransferEnabled() {
if (!transferEnabled) {
require(msg.sender == adminAddr || msg.sender == crowdSaleAddr);
}
_;
}
/**
* The listed addresses are not valid recipients of tokens.
*
* 0x0 - the zero address is not valid
* this - the contract itself should not receive tokens
* owner - the owner has all the initial tokens, but cannot receive any back
* adminAddr - the admin has an allowance of tokens to transfer, but does not receive any
* crowdSaleAddr - the crowdsale has an allowance of tokens to transfer, but does not receive any
*/
modifier validDestination(address _to) {
require(_to != address(0x0));
require(_to != address(this));
require(_to != owner);
require(_to != address(adminAddr));
require(_to != address(crowdSaleAddr));
_;
}
/**
* Constructor - instantiates token supply and allocates balanace of
* to the owner (msg.sender).
*/
function QuantstampToken(address _admin) {
// the owner is a custodian of tokens that can
// give an allowance of tokens for crowdsales
// or to the admin, but cannot itself transfer
// tokens; hence, this requirement
require(msg.sender != _admin);
totalSupply = INITIAL_SUPPLY;
crowdSaleAllowance = CROWDSALE_ALLOWANCE;
adminAllowance = ADMIN_ALLOWANCE;
// mint all tokens
balances[msg.sender] = totalSupply;
Transfer(address(0x0), msg.sender, totalSupply);
adminAddr = _admin;
approve(adminAddr, adminAllowance);
}
/**
* Associates this token with a current crowdsale, giving the crowdsale
* an allowance of tokens from the crowdsale supply. This gives the
* crowdsale the ability to call transferFrom to transfer tokens to
* whomever has purchased them.
*
* Note that if _amountForSale is 0, then it is assumed that the full
* remaining crowdsale supply is made available to the crowdsale.
*
* @param _crowdSaleAddr The address of a crowdsale contract that will sell this token
* @param _amountForSale The supply of tokens provided to the crowdsale
*/
function setCrowdsale(address _crowdSaleAddr, uint256 _amountForSale) external onlyOwner {
require(!transferEnabled);
require(_amountForSale <= crowdSaleAllowance);
// if 0, then full available crowdsale supply is assumed
uint amount = (_amountForSale == 0) ? crowdSaleAllowance : _amountForSale;
// Clear allowance of old, and set allowance of new
approve(crowdSaleAddr, 0);
approve(_crowdSaleAddr, amount);
crowdSaleAddr = _crowdSaleAddr;
}
/**
* Enables the ability of anyone to transfer their tokens. This can
* only be called by the token owner. Once enabled, it is not
* possible to disable transfers.
*/
function enableTransfer() external onlyOwner {
transferEnabled = true;
approve(crowdSaleAddr, 0);
approve(adminAddr, 0);
crowdSaleAllowance = 0;
adminAllowance = 0;
}
/**
* Overrides ERC20 transfer function with modifier that prevents the
* ability to transfer tokens until after transfers have been enabled.
*/
function transfer(address _to, uint256 _value) public onlyWhenTransferEnabled validDestination(_to) returns (bool) {
return super.transfer(_to, _value);
}
/**
* Overrides ERC20 transferFrom function with modifier that prevents the
* ability to transfer tokens until after transfers have been enabled.
*/
function transferFrom(address _from, address _to, uint256 _value) public onlyWhenTransferEnabled validDestination(_to) returns (bool) {
bool result = super.transferFrom(_from, _to, _value);
if (result) {
if (msg.sender == crowdSaleAddr)
crowdSaleAllowance = crowdSaleAllowance.sub(_value);
if (msg.sender == adminAddr)
adminAllowance = adminAllowance.sub(_value);
}
return result;
}
/**
* Overrides the burn function so that it cannot be called until after
* transfers have been enabled.
*
* @param _value The amount of tokens to burn in mini-QSP
*/
function burn(uint256 _value) public {
require(transferEnabled || msg.sender == owner);
require(balances[msg.sender] >= _value);
super.burn(_value);
Transfer(msg.sender, address(0x0), _value);
}
}
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