pragma solidity ^0.4.19;
// ----------------------------------------------------------------------------
// 'SEDO PoW Token' contract
// Mineable ERC20 / ERC918 Token using Proof Of Work
// Supported Merge Mining with 0xbitcoin and other compatible tokens
// Based on technologies of 0xBitcoin (0xbitcoin.org)
// Many thanks to the Mikers help (http://mike.rs) for pool help
// ********************************************************
// S.E.D.O. web site: http://sedocoin.org
// S.E.D.O. pool address: http://pool.sedocoin.org
// ********************************************************
// Symbol : SEDO
// Name : SEDO PoW Token
// Total supply: 50,000,000.00
// Premine : 1,000,000
// Decimals : 8
// Rewards : 25 (initial)
// ********************************************************
// Safe maths
// ----------------------------------------------------------------------------
library SafeMath {
function add(uint a, uint b) internal pure returns (uint c) {
c = a + b;
require(c >= a);
}
function sub(uint a, uint b) internal pure returns (uint c) {
require(b <= a);
c = a - b;
}
function mul(uint a, uint b) internal pure returns (uint c) {
c = a * b;
require(a == 0 || c / a == b);
}
function div(uint a, uint b) internal pure returns (uint c) {
require(b > 0);
c = a / b;
}
}
library ExtendedMath {
//return the smaller of the two inputs (a or b)
function limitLessThan(uint a, uint b) internal pure returns (uint c) {
if(a > b) return b;
return a;
}
}
// ----------------------------------------------------------------------------
// ERC Token Standard #20 Interface
// https://github.com/ethereum/EIPs/blob/master/EIPS/eip-20-token-standard.md
// ----------------------------------------------------------------------------
contract ERC20Interface {
function totalSupply() public constant returns (uint);
function balanceOf(address tokenOwner) public constant returns (uint balance);
function allowance(address tokenOwner, address spender) public constant returns (uint remaining);
function transfer(address to, uint tokens) public returns (bool success);
function approve(address spender, uint tokens) public returns (bool success);
function transferFrom(address from, address to, uint tokens) public returns (bool success);
event Transfer(address indexed from, address indexed to, uint tokens);
event Approval(address indexed tokenOwner, address indexed spender, uint tokens);
}
// ----------------------------------------------------------------------------
// Contract function to receive approval and execute function in one call
//
// Borrowed from MiniMeToken
// ----------------------------------------------------------------------------
contract ApproveAndCallFallBack {
function receiveApproval(address from, uint256 tokens, address token, bytes data) public;
}
// ----------------------------------------------------------------------------
// Owned contract
// ----------------------------------------------------------------------------
contract Owned {
address public owner;
address public newOwner;
event OwnershipTransferred(address indexed _from, address indexed _to);
function Owned() public {
owner = msg.sender;
}
modifier onlyOwner {
require(msg.sender == owner);
_;
}
function transferOwnership(address _newOwner) public onlyOwner {
newOwner = _newOwner;
}
function acceptOwnership() public {
require(msg.sender == newOwner);
OwnershipTransferred(owner, newOwner);
owner = newOwner;
newOwner = address(0);
}
}
// ----------------------------------------------------------------------------
// EIP-918 Interface
// https://github.com/ethereum/EIPs/blob/master/EIPS/eip-918.md
// ----------------------------------------------------------------------------
contract ERC918Interface {
function totalSupply() public constant returns (uint);
function getMiningDifficulty() public constant returns (uint);
function getMiningTarget() public constant returns (uint);
function getMiningReward() public constant returns (uint);
function balanceOf(address tokenOwner) public constant returns (uint balance);
function mint(uint256 nonce, bytes32 challenge_digest) public returns (bool success);
event Mint(address indexed from, uint reward_amount, uint epochCount, bytes32 newChallengeNumber);
address public lastRewardTo;
uint public lastRewardAmount;
uint public lastRewardEthBlockNumber;
bytes32 public challengeNumber;
}
// ----------------------------------------------------------------------------
// ERC20 Token, with the addition of symbol, name and decimals and an
// initial fixed supply
// ----------------------------------------------------------------------------
contract SedoPoWToken is ERC20Interface, Owned {
using SafeMath for uint;
using ExtendedMath for uint;
string public symbol;
string public name;
uint8 public decimals;
uint public _totalSupply;
uint public latestDifficultyPeriodStarted;
uint public epochCount;//number of 'blocks' mined
uint public _BLOCKS_PER_READJUSTMENT = 1024;
//a little number
uint public _MINIMUM_TARGET = 2**16;
uint public _MAXIMUM_TARGET = 2**234;
uint public miningTarget;
bytes32 public challengeNumber; //generate a new one when a new reward is minted
uint public rewardEra;
uint public maxSupplyForEra;
address public lastRewardTo;
uint public lastRewardAmount;
uint public lastRewardEthBlockNumber;
bool locked = false;
mapping(bytes32 => bytes32) solutionForChallenge;
uint public tokensMinted;
address public parentAddress; //address of 0xbtc
uint public miningReward; //initial reward
mapping(address => uint) balances;
mapping(address => uint) merge_mint_ious;
mapping(address => uint) merge_mint_payout_threshold;
mapping(address => mapping(address => uint)) allowed;
event Mint(address indexed from, uint reward_amount, uint epochCount, bytes32 newChallengeNumber);
// ------------------------------------------------------------------------
// Constructor
// ------------------------------------------------------------------------
function SedoPoWToken() public onlyOwner{
symbol = "SEDO";
name = "SEDO PoW Token";
decimals = 8;
_totalSupply = 50000000 * 10**uint(decimals);
if(locked) revert();
locked = true;
tokensMinted = 1000000 * 10**uint(decimals);
miningReward = 25; //initial Mining reward for 1st half of totalSupply (50 000 000 / 2)
rewardEra = 0;
maxSupplyForEra = _totalSupply.div(2);
miningTarget = 2**220; //initial mining target
latestDifficultyPeriodStarted = block.number;
_startNewMiningEpoch();
parentAddress = 0x9D2Cc383E677292ed87f63586086CfF62a009010; //address of parent coin 0xBTC - need to be changed to actual in the mainnet !
//0xB6eD7644C69416d67B522e20bC294A9a9B405B31 - production
balances[owner] = balances[owner].add(tokensMinted);
Transfer(address(this), owner, tokensMinted);
}
// ------------------------------------------------------------------------
// Parent contract changing (it can be useful if parent will make a swap or in some other cases)
// ------------------------------------------------------------------------
function ParentCoinAddress(address parent) public onlyOwner{
parentAddress = parent;
}
// ------------------------------------------------------------------------
// Main mint function
// ------------------------------------------------------------------------
function mint(uint256 nonce, bytes32 challenge_digest) public returns (bool success) {
//the PoW must contain work that includes a recent ethereum block hash (challenge number) and the msg.sender's address to prevent MITM attacks
bytes32 digest = keccak256(challengeNumber, msg.sender, nonce );
//the challenge digest must match the expected
if (digest != challenge_digest) revert();
//the digest must be smaller than the target
if(uint256(digest) > miningTarget) revert();
//only allow one reward for each challenge
bytes32 solution = solutionForChallenge[challengeNumber];
solutionForChallenge[challengeNumber] = digest;
if(solution != 0x0) revert(); //prevent the same answer from awarding twice
uint reward_amount = getMiningReward();
balances[msg.sender] = balances[msg.sender].add(reward_amount);
tokensMinted = tokensMinted.add(reward_amount);
//Cannot mint more tokens than there are
assert(tokensMinted <= maxSupplyForEra);
//set readonly diagnostics data
lastRewardTo = msg.sender;
lastRewardAmount = reward_amount;
lastRewardEthBlockNumber = block.number;
_startNewMiningEpoch();
Mint(msg.sender, reward_amount, epochCount, challengeNumber );
emit Transfer(address(this), msg.sender, reward_amount); //we need add it to show token transfers in the etherscan
return true;
}
// ------------------------------------------------------------------------
// merge mint function
// ------------------------------------------------------------------------
function merge() public returns (bool success) {
// Function for the Merge mining (0xbitcoin as a parent coin)
// original idea by 0xbitcoin developers
// the idea is that the miner uses https://github.com/0xbitcoin/mint-helper/blob/master/contracts/MintHelper.sol
// to call mint() and then mergeMint() in the same transaction
// hard code a reference to the "Parent" ERC918 Contract ( in this case 0xBitcoin)
// Verify that the Parent contract was minted in this block, by the same person calling this contract
// then followthrough with the resulting mint logic
// don't call revert, but return true or false based on success
// this method shouldn't revert because it will be calleed in the same transaction as a "Parent" mint attempt
//ensure that mergeMint() can only be called once per Parent::mint()
//do this by ensuring that the "new" challenge number from Parent::challenge post mint can be called once
//and that this block time is the same as this mint, and the caller is msg.sender
//only allow one reward for each challenge
// do this by calculating what the new challenge will be in _startNewMiningEpoch, and verify that it is not that value
// this checks happen in the local contract, not in the parent
bytes32 future_challengeNumber = block.blockhash(block.number - 1);
if(challengeNumber == future_challengeNumber){
return false; // ( this is likely the second time that mergeMint() has been called in a transaction, so return false (don't revert))
}
if(ERC918Interface(parentAddress).lastRewardTo() != msg.sender){
return false; // a different address called mint last so return false ( don't revert)
}
if(ERC918Interface(parentAddress).lastRewardEthBlockNumber() != block.number){
return false; // parent::mint() was called in a different block number so return false ( don't revert)
}
//we have verified that _startNewMiningEpoch has not been run more than once this block by verifying that
// the challenge is not the challenge that will be set by _startNewMiningEpoch
//we have verified that this is the same block as a call to Parent::mint() and that the sender
// is the sender that has called mint
//SEDO will have the same challenge numbers as 0xBitcoin, this means that mining for one is literally the same process as mining for the other
// we want to make sure that one can't use a combination of merge and mint to get two blocks of SEDO for each valid nonce, since the same solution
// applies to each coin
// for this reason, we update the solutionForChallenge hashmap with the value of parent::challengeNumber when a solution is merge minted.
// when a miner finds a valid solution, if they call this::mint(), without the next few lines of code they can then subsequently use the mint helper and in one transaction
// call parent::mint() this::merge(). the following code will ensure that this::merge() does not give a block reward, because the challenge number will already be set in the
// solutionForChallenge map
//only allow one reward for each challenge based on parent::challengeNumber
bytes32 parentChallengeNumber = ERC918Interface(parentAddress).challengeNumber();
bytes32 solution = solutionForChallenge[parentChallengeNumber];
if(solution != 0x0) return false; //prevent the same answer from awarding twice
//now that we've checked that the next challenge wasn't reused, apply the current SEDO challenge
//this will prevent the 'previous' challenge from being reused
bytes32 digest = 'merge';
solutionForChallenge[challengeNumber] = digest;
//so now we may safely run the relevant logic to give an award to the sender, and update the contract
uint reward_amount = getMiningReward();
balances[msg.sender] = balances[msg.sender].add(reward_amount);
tokensMinted = tokensMinted.add(reward_amount);
//Cannot mint more tokens than there are
assert(tokensMinted <= maxSupplyForEra);
//set readonly diagnostics data
lastRewardTo = msg.sender;
lastRewardAmount = reward_amount;
lastRewardEthBlockNumber = block.number;
_startNewMiningEpoch();
Mint(msg.sender, reward_amount, epochCount, 0 ); // use 0 to indicate a merge mine
return true;
}
//a new 'block' to be mined
function _startNewMiningEpoch() internal {
//if max supply for the era will be exceeded next reward round then enter the new era before that happens
//40 is the final reward era, almost all tokens minted
//once the final era is reached, more tokens will not be given out because the assert function
if( tokensMinted.add(getMiningReward()) > maxSupplyForEra && rewardEra < 39)
{
rewardEra = rewardEra + 1;
}
//set the next minted supply at which the era will change
// total supply is 5000000000000000 because of 8 decimal places
maxSupplyForEra = _totalSupply - _totalSupply.div( 2**(rewardEra + 1));
epochCount = epochCount.add(1);
//every so often, readjust difficulty. Dont readjust when deploying
if(epochCount % _BLOCKS_PER_READJUSTMENT == 0)
{
_reAdjustDifficulty();
}
//make the latest ethereum block hash a part of the next challenge for PoW to prevent pre-mining future blocks
//do this last since this is a protection mechanism in the mint() function
challengeNumber = block.blockhash(block.number - 1);
}
//https://en.bitcoin.it/wiki/Difficulty#What_is_the_formula_for_difficulty.3F
//as of 2017 the bitcoin difficulty was up to 17 zeroes, it was only 8 in the early days
//readjust the target by 5 percent
function _reAdjustDifficulty() internal {
uint ethBlocksSinceLastDifficultyPeriod = block.number - latestDifficultyPeriodStarted;
uint epochsMined = _BLOCKS_PER_READJUSTMENT; //256
uint targetEthBlocksPerDiffPeriod = epochsMined * 60; //should be 60 times slower than ethereum
//if there were less eth blocks passed in time than expected
if( ethBlocksSinceLastDifficultyPeriod < targetEthBlocksPerDiffPeriod )
{
uint excess_block_pct = (targetEthBlocksPerDiffPeriod.mul(100)).div( ethBlocksSinceLastDifficultyPeriod );
uint excess_block_pct_extra = excess_block_pct.sub(100).limitLessThan(1000);
// If there were 5% more blocks mined than expected then this is 5. If there were 100% more blocks mined than expected then this is 100.
//make it harder
miningTarget = miningTarget.sub(miningTarget.div(2000).mul(excess_block_pct_extra)); //by up to 50 %
}else{
uint shortage_block_pct = (ethBlocksSinceLastDifficultyPeriod.mul(100)).div( targetEthBlocksPerDiffPeriod );
uint shortage_block_pct_extra = shortage_block_pct.sub(100).limitLessThan(1000); //always between 0 and 1000
//make it easier
miningTarget = miningTarget.add(miningTarget.div(2000).mul(shortage_block_pct_extra)); //by up to 50 %
}
latestDifficultyPeriodStarted = block.number;
if(miningTarget < _MINIMUM_TARGET) //very difficult
{
miningTarget = _MINIMUM_TARGET;
}
if(miningTarget > _MAXIMUM_TARGET) //very easy
{
miningTarget = _MAXIMUM_TARGET;
}
}
//this is a recent ethereum block hash, used to prevent pre-mining future blocks
function getChallengeNumber() public constant returns (bytes32) {
return challengeNumber;
}
//the number of zeroes the digest of the PoW solution requires. Auto adjusts
function getMiningDifficulty() public constant returns (uint) {
return _MAXIMUM_TARGET.div(miningTarget);
}
function getMiningTarget() public constant returns (uint) {
return miningTarget;
}
//50m coins total
//reward begins at miningReward and is cut in half every reward era (as tokens are mined)
function getMiningReward() public constant returns (uint) {
//once we get half way thru the coins, only get 25 per block
//every reward era, the reward amount halves.
return (miningReward * 10**uint(decimals) ).div( 2**rewardEra ) ;
}
//help debug mining software
function getMintDigest(uint256 nonce, bytes32 challenge_digest, bytes32 challenge_number) public view returns (bytes32 digesttest) {
bytes32 digest = keccak256(challenge_number,msg.sender,nonce);
return digest;
}
//help debug mining software
function checkMintSolution(uint256 nonce, bytes32 challenge_digest, bytes32 challenge_number, uint testTarget) public view returns (bool success) {
bytes32 digest = keccak256(challenge_number,msg.sender,nonce);
if(uint256(digest) > testTarget) revert();
return (digest == challenge_digest);
}
// ------------------------------------------------------------------------
// Total supply
// ------------------------------------------------------------------------
function totalSupply() public constant returns (uint) {
return _totalSupply - balances[address(0)];
}
// ------------------------------------------------------------------------
// Get the token balance for account `tokenOwner`
// ------------------------------------------------------------------------
function balanceOf(address tokenOwner) public constant returns (uint balance) {
return balances[tokenOwner];
}
// ------------------------------------------------------------------------
// Transfer the balance from token owner's account to `to` account
// - Owner's account must have sufficient balance to transfer
// - 0 value transfers are allowed
// ------------------------------------------------------------------------
function transfer(address to, uint tokens) public returns (bool success) {
balances[msg.sender] = balances[msg.sender].sub(tokens);
balances[to] = balances[to].add(tokens);
Transfer(msg.sender, to, tokens);
return true;
}
// ------------------------------------------------------------------------
// Token owner can approve for `spender` to transferFrom(...) `tokens`
// from the token owner's account
//
// https://github.com/ethereum/EIPs/blob/master/EIPS/eip-20-token-standard.md
// recommends that there are no checks for the approval double-spend attack
// as this should be implemented in user interfaces
// ------------------------------------------------------------------------
function approve(address spender, uint tokens) public returns (bool success) {
allowed[msg.sender][spender] = tokens;
Approval(msg.sender, spender, tokens);
return true;
}
// ------------------------------------------------------------------------
// Transfer `tokens` from the `from` account to the `to` account
//
// The calling account must already have sufficient tokens approve(...)-d
// for spending from the `from` account and
// - From account must have sufficient balance to transfer
// - Spender must have sufficient allowance to transfer
// - 0 value transfers are allowed
// ------------------------------------------------------------------------
function transferFrom(address from, address to, uint tokens) public returns (bool success) {
balances[from] = balances[from].sub(tokens);
allowed[from][msg.sender] = allowed[from][msg.sender].sub(tokens);
balances[to] = balances[to].add(tokens);
Transfer(from, to, tokens);
return true;
}
// ------------------------------------------------------------------------
// Returns the amount of tokens approved by the owner that can be
// transferred to the spender's account
// ------------------------------------------------------------------------
function allowance(address tokenOwner, address spender) public constant returns (uint remaining) {
return allowed[tokenOwner][spender];
}
// ------------------------------------------------------------------------
// Token owner can approve for `spender` to transferFrom(...) `tokens`
// from the token owner's account. The `spender` contract function
// `receiveApproval(...)` is then executed
// ------------------------------------------------------------------------
function approveAndCall(address spender, uint tokens, bytes data) public returns (bool success) {
allowed[msg.sender][spender] = tokens;
Approval(msg.sender, spender, tokens);
ApproveAndCallFallBack(spender).receiveApproval(msg.sender, tokens, this, data);
return true;
}
// ------------------------------------------------------------------------
// Don't accept ETH
// ------------------------------------------------------------------------
function () public payable {
revert();
}
// ------------------------------------------------------------------------
// Owner can transfer out any accidentally sent ERC20 tokens
// ------------------------------------------------------------------------
function transferAnyERC20Token(address tokenAddress, uint tokens) public onlyOwner returns (bool success) {
return ERC20Interface(tokenAddress).transfer(owner, tokens);
}
}
{
"compilationTarget": {
"SedoPoWToken.sol": "SedoPoWToken"
},
"evmVersion": "byzantium",
"libraries": {},
"optimizer": {
"enabled": true,
"runs": 200
},
"remappings": []
}
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2"},{"name":"challenge_number","type":"bytes32"}],"name":"getMintDigest","outputs":[{"name":"digesttest","type":"bytes32"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"to","type":"address"},{"name":"tokens","type":"uint256"}],"name":"transfer","outputs":[{"name":"success","type":"bool"}],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[],"name":"_BLOCKS_PER_READJUSTMENT","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"lastRewardAmount","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"spender","type":"address"},{"name":"tokens","type":"uint256"},{"name":"data","type":"bytes"}],"name":"approveAndCall","outputs":[{"name":"success","type":"bool"}],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[],"name":"latestDifficultyPeriodStarted","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"newOwner","outputs":[{"name":"","type":"address"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"tokenAddress","type":"address"},{"name":"tokens","type":"uint256"}],"name":"transferAnyERC20Token","outputs":[{"name":"success","type":"bool"}],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[],"name":"_MINIMUM_TARGET","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[{"name":"tokenOwner","type":"address"},{"name":"spender","type":"address"}],"name":"allowance","outputs":[{"name":"remaining","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"_newOwner","type":"address"}],"name":"transferOwnership","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"inputs":[],"payable":false,"stateMutability":"nonpayable","type":"constructor"},{"payable":true,"stateMutability":"payable","type":"fallback"},{"anonymous":false,"inputs":[{"indexed":true,"name":"from","type":"address"},{"indexed":false,"name":"reward_amount","type":"uint256"},{"indexed":false,"name":"epochCount","type":"uint256"},{"indexed":false,"name":"newChallengeNumber","type":"bytes32"}],"name":"Mint","type":"event"},{"anonymous":false,"inputs":[{"indexed":true,"name":"_from","type":"address"},{"indexed":true,"name":"_to","type":"address"}],"name":"OwnershipTransferred","type":"event"},{"anonymous":false,"inputs":[{"indexed":true,"name":"from","type":"address"},{"indexed":true,"name":"to","type":"address"},{"indexed":false,"name":"tokens","type":"uint256"}],"name":"Transfer","type":"event"},{"anonymous":false,"inputs":[{"indexed":true,"name":"tokenOwner","type":"address"},{"indexed":true,"name":"spender","type":"address"},{"indexed":false,"name":"tokens","type":"uint256"}],"name":"Approval","type":"event"}]