Hello world,
It’s been over 2 years since we updated our Crash algorithm with salting (
https://bitcointalksearch.org/topic/crash-game-reseeding-event-bcgame-5256606). In our endeavor to constantly improve seed safety and provable fairness of our games, we will shortly be updating our Crash game with a new salted hash. The purpose of this post is for full transparency of this process.
CRASH GAME RESULT FORMULA
const gameResult = (seed, salt) => {
const nBits = 52; // number of most significant bits to use
// 1. HMAC_SHA256(message=seed, key=salt)
const hmac = CryptoJS.HmacSHA256(CryptoJS.enc.Hex.parse(seed), salt);
seed = hmac.toString(CryptoJS.enc.Hex);
// 2. r = 52 most significant bits
seed = seed.slice(0, nBits / 4);
const r = parseInt(seed, 16);
// 3. X = r / 2^52
let X = r / Math.pow(2, nBits); // uniformly distributed in [0; 1)
X = parseFloat(X.toPrecision(9));
// 4. X = 99 / (1-X)
X = 99 / (1 - X);
// 5. return max(trunc(X), 100)
const result = Math.floor(X);
return Math.max(1, result / 100);
};
Prior to being used for calculation, each game hash is salted with the lowercase + hexadecimal string representation of the hash from pre-selected Bitcoin block 758,160. This block has not been mined yet as of this post, proving that we have not deliberately selected a mined block with a hash that could be favorable to the house. Once block 758,160 has been mined, the results will be posted to this thread as a reply. The game this post is referencing is at
https://bc.game/game/crash 
