0x5d2d...0176

Lottery / Gambling

0x5d2d1d87afde...674489800176

FrontierContract #754Exact Bytecode MatchEdit this contract

Deployed September 3, 2015 (11 years ago)Block 177,982

A coin flip wager contract that reads the current block hash and gets zero back, endowed with 1 ETH on 3 September 2015.

Frontier EraVerified Source

Historical Significance

Randomness is the problem gambling contracts exist to expose. Every value available inside the EVM is either known in advance or chosen by the account producing the block, so a payout decided from block data can be steered by whoever mines it. This run of revisions is that lesson being learned in public, one deployment at a time, and the answer the ecosystem eventually reached, an oracle or a commit and reveal, is not available here at all.

Context

Deployed a month after the Frontier launch, when no contract could yet draw randomness from anything but block data.

Key Facts

Deployer

Cyrus Adkisson(0xcf684d...ad1bac)

Deployment Block

177,982

Deployment Date

Sep 3, 2015, 12:29 AM

Code Size

2.5 KB

Gas at Deploy

706,771

Transactions by Year

20152

Deployment Transaction: 0x328a8c4b417f73af...1beff45735309190

Description

This revision stores block.blockhash(block.number) into a state variable on every flip. That call returns zero, because the hash of the block being executed does not exist yet, and the source carries the author's note recording the result and saying he did not know why. The payout still turns on hashing block difficulty, the coinbase address, the timestamp and the wager, so the zero value is recorded rather than used. A kill function was used, so no code remains and the source is matched against the bytecode as archived at deployment. Deployed by Cyrus Adkisson from 0xcf684dfb8304729355b58315e8019b1aa2ad1bac.

Source Verified

Exact bytecode match(2,569 bytes)

Compiler: v0.1.1+

View verification proof

Historian Categories

Lottery / Gambling

Heuristic Analysis

The following characteristics were detected through bytecode analysis and may not be accurate.

Detected Type: Lottery / Gambling

Frontier Era

The initial release of Ethereum. A bare-bones implementation for technical users.

Block span: 0 — 1,149,999

July 30, 2015 — March 14, 2016

Bytecode Overview

Opcodes2,569

Unique Opcodes147

Jump Instructions124

Storage Operations45

Verified Source Available

Source verified through compiler archaeology and exact bytecode matching.

View Verification Proof

Show source code (Solidity)

// Submitted by EthereumHistory (ethereumhistory.com)
contract CoinFlipper {

    address creator;
    uint contract_creation_value;	// original endowment
    int lastgainloss;
    string lastresult;
    uint lastblocknumberused;
    bytes32 lastblockhashused;
//	 uint8 numbetsmade; // this doesn't work


    function CoinFlipper() private 
    {
        creator = msg.sender; 								// msg is a global variable
        lastresult = "no wagers yet";
        lastgainloss = 0;
    }
	
    function getEndowmentBalance() constant returns (uint)
    {
    	return this.balance;
    }
    
    function sha(uint128 wager) constant private returns(uint256)  
    { 
        return uint256(sha3(block.difficulty, block.coinbase, now, wager));  // DISCLAIMER: I don't know if this is random enough.
    }
    
    function betAndFlip() public               
    {
   		//numbetsmade = (numbetsmade + 1); // compiles but doesn't work. 
    	if(msg.value > 340282366920938463463374607431768211455)                 // this number is 2^128 - 1 = uint128 limit
    	{
    		// if too large, return wager
    		lastresult = "wager too large";
    		lastgainloss = 0;
    		msg.sender.send(msg.value);
    		return;
    	}		  
    	else if((msg.value * 2) > this.balance) 			// contract has to have 2*wager funds to be able to pay out. (current balance INCLUDES the wager sent)
    	{
    		lastresult = "wager larger than contract's ability to pay";
    		lastgainloss = 0;
    		msg.sender.send(msg.value);
    		return;
    	}
    	else if (msg.value == 0)
    	{
    		lastresult = "wager was zero";
    		lastgainloss = 0;
    		// nothing wagered, nothing returned
    		return;
    	}
    		
    	uint128 wager = uint128(msg.value);          // limiting to uint128 guarantees that conversion to int256 will stay positive
    	
    	lastblocknumberused = block.number;
    	lastblockhashused = block.blockhash(block.number); // is returning 0x000... right now. Don't know why.
    	
	   	uint hash = sha(wager);
	    if( hash % 2 == 0 )
	   	{
	    	lastgainloss = int(wager) * -1;
	    	lastresult = "loss";
	    	// they lost. Return nothing.
	    	return;
	    }
	    else
	    {
	    	lastgainloss = wager;
	    	lastresult = "win";
	    	msg.sender.send(wager * 2);
	    } 		
    }
    
  //  numbetsmade isn't working. Don't know why 
  //  function getNumBetsMade() constant returns (uint8)
  //  {
  //  	return numbetsmade;
  //  }
    
  	function getLastBlockNumberUsed() constant returns (uint)
    {
        return lastblocknumberused;
    }
    
    function getLastBlockHashUsed() constant returns (bytes32)
    {
    	return lastblockhashused;
    }

    function getResultOfLastFlip() constant returns (string)
    {
    	return lastresult;
    }
    
    function getPlayerGainLossOnLastFlip() constant returns (int)
    {
    	return lastgainloss;
    }
        
    /**********
     Standard kill() function to recover funds 
     **********/
    
    function kill()
    { 
        if (msg.sender == creator)
        {
            suicide(creator);  // kills this contract and sends remaining funds back to creator
        }
    }
}

/*

var coinflipperContract = web3.eth.contract([{
    "constant": true,
    "inputs": [],
    "name": "getPlayerGainLossOnLastFlip",
    "outputs": [{
        "name": "",
        "type": "int256"
    }],
    "type": "function"
}, {
    "constant": false,
    "inputs": [],
    "name": "betAndFlip",
    "outputs": [],
    "type": "function"
}, {
    "constant": true,
    "inputs": [],
    "name": "getLastBlockNumberUsed",
    "outputs": [{
        "name": "",
        "type": "uint256"
    }],
    "type": "function"
}, {
    "constant": false,
    "inputs": [],
    "name": "kill",
    "outputs": [],
    "type": "function"
}, {
    "constant": true,
    "inputs": [],
    "name": "getEndowmentBalance",
    "outputs": [{
        "name": "",
        "type": "uint256"
    }],
    "type": "function"
}, {
    "constant": true,
    "inputs": [],
    "name": "getLastBlockHashUsed",
    "outputs": [{
        "name": "",
        "type": "bytes32"
    }],
    "type": "function"
}, {
    "constant": true,
    "inputs": [],
    "name": "getResultOfLastFlip",
    "outputs": [{
        "name": "",
        "type": "string"
    }],
    "type": "function"
}, {
    "inputs": [],
    "type": "constructor"
}]);

var coinflipper = coinflipperContract.new({
    from: web3.eth.accounts[0],
    data: '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',
    gas: 1000000,
    value: 1000000000000000000
}, function(e, contract) {
    if (typeof contract.address != 'undefined') {
        console.log(e, contract);
        console.log('Contract mined! address: ' + contract.address + ' transactionHash: ' + contract.transactionHash);
    }
});

0x18487f6fa9c9d809940b0d6d2626f33f0c729e4c

// ********** after deployment

> coinflipper.getEndowmentBalance();
6000000000000000000
> coinflipper.betAndFlip.sendTransaction({from:eth.coinbase, value: 1000000000000000000}); // 1 ETH. Let's see what happens
"0xc78a24881c7f70d25a817dcfcdce3347ca0cd265b7ba30a60df61e5639482bcf"
> coinflipper.getResultOfLastFlip();
"no wagers yet"
> coinflipper.getResultOfLastFlip(); // has the tx been mined yet?
"no wagers yet"
> coinflipper.getResultOfLastFlip(); // has the tx been mined yet?
"no wagers yet"
> coinflipper.getResultOfLastFlip(); // has the tx been mined yet? I'm waiting...
"no wagers yet"
> coinflipper.getResultOfLastFlip(); // has the tx been mined yet? I'm waiting...
"win"
> coinflipper.getPlayerGainLossOnLastFlip();
1000000000000000000
> web3.fromWei(coinflipper.getPlayerGainLossOnLastFlip());
1
> coinflipper.getEndowmentBalance();
5000000000000000000
> coinflipper.betAndFlip.sendTransaction({from:eth.coinbase, value: 3000000000000000000}); // 3 ETH. Let's see what happens
"0xcae272652649e07c343674d15b40a086c559408d9c66d8022de3f54932bf3d9f"
> coinflipper.getResultOfLastFlip(); // has the tx been mined yet? I'm waiting...
"loss"
> coinflipper.getEndowmentBalance();
8000000000000000000
> web3.fromWei(coinflipper.getPlayerGainLossOnLastFlip());
-3
> web3.eth.getBalance(eth.coinbase);
1806931309200681965
> web3.fromWei(web3.eth.getBalance(eth.coinbase));
1.806931309200681965
> coinflipper.betAndFlip.sendTransaction({from:eth.coinbase, value: 1500000000000000000}); // 1.5 ETH. Let's see what happens
"0xc99add577b3180ca58b1a8219f2cd282f6b77edb63e1e384b05abc434753b1a1"
> coinflipper.getResultOfLastFlip(); // has the tx been mined yet? I'm waiting...
"win"
> web3.fromWei(web3.eth.getBalance(eth.coinbase));
3.304471659200681965
> web3.fromWei(web3.eth.getBalance(eth.coinbase));
> coinflipper.kill.sendTransaction({from:eth.coinbase});
"0xed9f9e49cca76965ba32acce2b2f0b17ada467e52d55b803c26cc7132ba108fa"
  
  
 // ************** after separate deployment with smaller endowment to test payout safety limit
 
  Contract mined! address: 0xb0824b45f4a4c1ee4df356378d555c7f4366fa4c transactionHash: 0x065580a137654a816abdeb27e690e6c96f59dce92a9e8064f6f8c3c49cf0b681

> coinflipper.getEndowmentBalance();   // 1 eth
1000000000000000000
> coinflipper.betAndFlip.sendTransaction({from:eth.coinbase, value: 3000000000000000000}); // 3 ETH, more than endowment can handle. Let's see what happens
"0x66b5ae12f215d1bcf1a1656f79ccedc69612dc891f35dce5dbd6ead8854f0cb1"
> coinflipper.getResultOfLastFlip(); // has the tx been mined yet? I'm waiting...
"no wagers yet"
> coinflipper.getResultOfLastFlip(); // has the tx been mined yet? I'm waiting...
"no wagers yet"
> coinflipper.getResultOfLastFlip(); // has the tx been mined yet? I'm waiting...
"no wagers yet"
> coinflipper.getResultOfLastFlip(); // has the tx been mined yet? I'm waiting...
"wager larger than contract's ability to pay"
> coinflipper.getEndowmentBalance();
1000000000000000000
> coinflipper.betAndFlip.sendTransaction({from:eth.coinbase, value: 500000000000000000}); // .5 ETH.
"0x16ef5f3f0778b1252dcfd3b55f09ab97382f23d8ad7489f1f1b45d88eb7588f5"
> coinflipper.getResultOfLastFlip(); // has the tx been mined yet? I'm waiting...
"loss"
  
  
  
 */

External Links

Etherscan Verified Source (if any)

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