Back to HomeDeployer Cyrus Adkisson(0xcf684d...ad1bac) Deployment Block 177,905 Deployment Date Sep 2, 2015, 11:58 PM Code Size 2.4 KB Gas at Deploy 687,258
Deployed September 2, 2015 (11 years ago)Block 177,905
A coin flip wager contract endowed with 1 ETH, deployed 2 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
Transactions by Year
20152
Deployment Transaction: 0xdb3a627df1f26e09...8d3955598f496443
Description
The player attaches a wager to betAndFlip and the contract pays double on a win or keeps the stake on a loss, refusing any bet above the uint128 limit or larger than the bankroll can cover at two to one. The outcome comes from hashing block difficulty, the coinbase address, the timestamp and the wager. The source carries a commented out attempt to use a block hash instead, along with the storage slot it would have needed, so the alternative was written down but not switched on. 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
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
Opcodes2,496
Unique Opcodes139
Jump Instructions118
Storage Operations45
Verified Source Available
Source verified through compiler archaeology and exact bytecode matching.
View Verification ProofShow 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;
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) // DISCLAIMER: This is pretty random... but not truly random.
{
return uint256(sha3(block.difficulty, block.coinbase, now, wager));
}
function betAndFlip() public
{
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 - 1);
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);
}
}
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": "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: 6000000000000000000 // start with endowment of 6 ETH
}, function(e, contract) {
if (typeof contract.address != 'undefined') {
console.log(e, contract);
console.log('Contract mined! address: ' + contract.address + ' transactionHash: ' + contract.transactionHash);
}
});
// ********** 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
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