Back to HomeDeployer Cyrus Adkisson(0xcf684d...ad1bac) Deployment Block 177,895 Deployment Date Sep 2, 2015, 11:50 PM Code Size 2.4 KB Gas at Deploy 666,784
Deployed September 2, 2015 (11 years ago)Block 177,895
A coin flip wager contract that refuses bets the bankroll cannot cover, endowed with 1 ETH on 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: 0xc6fbc2429651efd4...4bc20e7038181bfa
Description
Deployed the same day as an earlier attempt and differing in one respect: the contract now rejects any wager larger than half its own balance, returning the money rather than accepting a bet it could not pay out at two to one. It also rejects wagers above the uint128 limit. The outcome still comes from hashing block difficulty, the coinbase address, the timestamp and the wager. A kill function was used, so no code remains at the address 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
Opcodes2,418
Unique Opcodes136
Jump Instructions119
Storage Operations46
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;
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
{
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
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 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": 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: '60606040525b33600060006101000a81548173ffffffffffffffffffffffffffffffffffffffff02191690830217905550604060405190810160405280600d81526020017f6e6f2077616765727320796574000000000000000000000000000000000000008152602001506003600050908051906020019082805482825590600052602060002090601f0160209004810192821560b7579182015b8281111560b6578251826000505591602001919060010190609a565b5b50905060de919060c2565b8082111560da576000818150600090555060010160c2565b5090565b505060006002600050819055505b610877806100fb6000396000f30060606040526000357c0100000000000000000000000000000000000000000000000000000000900480630efafd011461006557806325d8dcf21461008657806341c0e1b5146100935780635acce36b146100a0578063cee6f93c146100c157610063565b005b610070600450610723565b6040518082815260200191505060405180910390f35b61009160045061013a565b005b61009e600450610735565b005b6100ab6004506107c9565b6040518082815260200191505060405180910390f35b6100cc6004506106a5565b60405180806020018281038252838181518152602001915080519060200190808383829060006004602084601f0104600302600f01f150905090810190601f16801561012c5780820380516001836020036101000a031916815260200191505b509250505060405180910390f35b600060006fffffffffffffffffffffffffffffffff34111561025457604060405190810160405280600f81526020017f776167657220746f6f206c6172676500000000000000000000000000000000008152602001506003600050908051906020019082805482825590600052602060002090601f016020900481019282156101e0579182015b828111156101df5782518260005055916020019190600101906101c1565b5b50905061020b91906101ed565b8082111561020757600081815060009055506001016101ed565b5090565b505060006002600050819055503373ffffffffffffffffffffffffffffffffffffffff16600034604051809050600060405180830381858888f19350505050506106a15661046c565b3073ffffffffffffffffffffffffffffffffffffffff163160023402111561039a57606060405190810160405280602b81526020017f7761676572206c6172676572207468616e20636f6e747261637427732061626981526020017f6c69747920746f207061790000000000000000000000000000000000000000008152602001506003600050908051906020019082805482825590600052602060002090601f01602090048101928215610326579182015b82811115610325578251826000505591602001919060010190610307565b5b5090506103519190610333565b8082111561034d5760008181506000905550600101610333565b5090565b505060006002600050819055503373ffffffffffffffffffffffffffffffffffffffff16600034604051809050600060405180830381858888f19350505050506106a15661046b565b600034141561046a57604060405190810160405280600e81526020017f776167657220776173207a65726f0000000000000000000000000000000000008152602001506003600050908051906020019082805482825590600052602060002090601f0160209004810192821561042d579182015b8281111561042c57825182600050559160200191906001019061040e565b5b509050610458919061043a565b80821115610454576000818150600090555060010161043a565b5090565b505060006002600050819055506106a1565b5b5b349150610478826107ed565b90506000600282061415610584577fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff826fffffffffffffffffffffffffffffffff1602600260005081905550604060405190810160405280600481526020017f6c6f7373000000000000000000000000000000000000000000000000000000008152602001506003600050908051906020019082805482825590600052602060002090601f0160209004810192821561054e579182015b8281111561054d57825182600050559160200191906001019061052f565b5b509050610579919061055b565b80821115610575576000818150600090555060010161055b565b5090565b50506106a1566106a0565b816fffffffffffffffffffffffffffffffff16600260005081905550604060405190810160405280600381526020017f77696e00000000000000000000000000000000000000000000000000000000008152602001506003600050908051906020019082805482825590600052602060002090601f0160209004810192821561062a579182015b8281111561062957825182600050559160200191906001019061060b565b5b5090506106559190610637565b808211156106515760008181506000905550600101610637565b5090565b50503373ffffffffffffffffffffffffffffffffffffffff166000600284026fffffffffffffffffffffffffffffffff16604051809050600060405180830381858888f19350505050505b5b5050565b60206040519081016040528060008152602001506003600050805480601f0160208091040260200160405190810160405280929190818152602001828054801561071457820191906000526020600020905b8154815290600101906020018083116106f757829003601f168201915b50505050509050610720565b90565b60006002600050549050610732565b90565b600060009054906101000a900473ffffffffffffffffffffffffffffffffffffffff1673ffffffffffffffffffffffffffffffffffffffff163373ffffffffffffffffffffffffffffffffffffffff1614156107c657600060009054906101000a900473ffffffffffffffffffffffffffffffffffffffff1673ffffffffffffffffffffffffffffffffffffffff16ff5b5b565b60003073ffffffffffffffffffffffffffffffffffffffff163190506107ea565b90565b600044414284604051808581526020018473ffffffffffffffffffffffffffffffffffffffff166c01000000000000000000000000028152601401838152602001826fffffffffffffffffffffffffffffffff167001000000000000000000000000000000000281526010019450505050506040518091039020600190049050610872565b91905056',
gas: 1000000,
value: 6000000000000000000 // endow with 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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