CoinFlipper

Utility

0x6c8dda9f172d...58b08d5ef84e

FrontierContract #81Exact Bytecode MatchEdit this contract

Deployed August 8, 2015 (11 years ago)Block 55,508

A coin flip on the block timestamp that pays double or keeps the stake

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 in August 2015, in the first month of the Frontier chain. The same account verified another contract of its own with the identical interface, which is where the name comes from.

Key Facts

Deployer

0xc70ba2...af62e9

Deployment Block

55,508

Deployment Date

Aug 8, 2015, 10:11 PM

Code Size

197.0 B

Gas at Deploy

69,947

Deployment Transaction: 0xbf7a49b48da8c14f...e438b8d2e141d578

Description

Send it more than twice its own balance and it flips: the low bit of the block timestamp is written to storage as the result, and if that bit is set the sender is paid back twice what they sent, otherwise the contract keeps everything. Anything less than twice the balance is refused outright, which caps the payout at what the contract can cover. A donate function exists solely to fund it, and the flip result stays readable afterwards. The randomness is the timestamp, which the miner producing the block chooses.

Source Verified

Exact bytecode match(197 bytes)

Compiler: v0.1.1+

View verification proof

Heuristic Analysis

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

Detected Type: Utility

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

Opcodes197

Unique Opcodes57

Jump Instructions13

Storage Operations3

Verified Source Available

Source verified through compiler archaeology and exact bytecode matching.

Verified on Etherscan

View Verification Proof

Show source code (Solidity)

// Submitted by EthereumHistory (ethereumhistory.com)
contract CoinFlipper {
    uint8 public flip;
    function donate() {
    }
    function() {
        var v = msg.value;
        var b = address(this).balance;
        if (v < 2 * b) {
            return;
        }
        flip = uint8(block.timestamp % 2);
        if (flip == 0) {
        } else {
            msg.sender.send(2 * v);
        }
    }
}