Disclaimer: I was hired by steemcrash.com to make this seeding event and therefore set up the provably fair on the game. I will not be part of the team that will manage this site.
This will reuse the idea posted by Ryan and used for Bustabit.
The reference code (javascript) is as follows:
The method to create the hash chain is simply sha256:
The method to convert a game hash, mix it with the picked client seed to a money pot multiplier:
The chain could be generated with code such as:
Using our chosen starting serverSeed, the hash terminating the chain is e68e26b9ae2090dde4be1e00af21c6d4ad271e76caa699ab8ff52f34033cb730. That is to say, the first game's hash played under the new provably fair scheme, when hashed will be e68e26b9ae2090dde4be1e00af21c6d4ad271e76caa699ab8ff52f34033cb730
This will reuse the idea posted by Ryan and used for Bustabit.
- A chain of 10 million sha256 hashes was generated, starting with a Server Secret that has been repeatedly fed the output of sha256 hash back into itself 10 million times.
The final hash in the chain is: e68e26b9ae2090dde4be1e00af21c6d4ad271e76caa699ab8ff52f34033cb730, by publicizing it here we are preventing any ability to pick an alternate sha256 chain. - SteemCrashwill play through that chain of hashes, in reverse order, and use the hashes to determine the crash point.
- To avoid criticism that the Server Secret used in step 1 was carefully chosen to generate lots of "bad" crash points, each hash in the chain will be salted with a client seed, which we have no control of.
The client seed will be the block hash of a Bitcoin block that hasn't yet been mined: block 484300.
The reference code (javascript) is as follows:
The method to create the hash chain is simply sha256:
Code:
function genGameHash(serverSeed) {
return crypto.createHash('sha256').update(serverSeed).digest('hex');
}
return crypto.createHash('sha256').update(serverSeed).digest('hex');
}
The method to convert a game hash, mix it with the picked client seed to a money pot multiplier:
Code:
function crashPointFromHash(serverSeed, clientSeed) {
function divisible(hash, mod) {
// We will read in 4 hex at a time, but the first chunk might be a bit smaller
// So ABCDEFGHIJ should be chunked like AB CDEF GHIJ
var val = 0;
var o = hash.length % 4;
for (var i = o > 0 ? o - 4 : 0; i < hash.length; i += 4) {
val = ((val << 16) + parseInt(hash.substring(i, i+4), 16)) % mod;
}
return val === 0;
}
var hash = crypto.createHmac('sha256', serverSeed).update(clientSeed).digest('hex');
/* In 1 of 101 games the game crashes instantly. */
if (divisible(hash, 101))
return 0;
/* Use the most significant 52-bit from the hash
to calculate the crash point */
var h = parseInt(hash.slice(0,52/4),16);
var e = Math.pow(2,52);
return Math.floor((100 * e - h) / (e - h));
}
function divisible(hash, mod) {
// We will read in 4 hex at a time, but the first chunk might be a bit smaller
// So ABCDEFGHIJ should be chunked like AB CDEF GHIJ
var val = 0;
var o = hash.length % 4;
for (var i = o > 0 ? o - 4 : 0; i < hash.length; i += 4) {
val = ((val << 16) + parseInt(hash.substring(i, i+4), 16)) % mod;
}
return val === 0;
}
var hash = crypto.createHmac('sha256', serverSeed).update(clientSeed).digest('hex');
/* In 1 of 101 games the game crashes instantly. */
if (divisible(hash, 101))
return 0;
/* Use the most significant 52-bit from the hash
to calculate the crash point */
var h = parseInt(hash.slice(0,52/4),16);
var e = Math.pow(2,52);
return Math.floor((100 * e - h) / (e - h));
}
The chain could be generated with code such as:
Code:
var serverSecret = 'If you knew this, you could steal all my money';
var clientSeed = '0000examplehash';
var gamesToGenerate = 1e7;
var serverSeed = serverSecret;
for (var game = gamesToGenerate; game > 0; --game) {
serverSeed = genGameHash(serverSeed);
console.log('Game ' + game + ' has a crash point of ' + (crashPointFromHash(serverSeed, clientSeed) / 100).toFixed(2) +'x', '\t\tHash: ' + serverSeed);
}
var terminatingHash = genGameHash(serverSeed);
console.log('The final hash is: ', terminatingHash);
var clientSeed = '0000examplehash';
var gamesToGenerate = 1e7;
var serverSeed = serverSecret;
for (var game = gamesToGenerate; game > 0; --game) {
serverSeed = genGameHash(serverSeed);
console.log('Game ' + game + ' has a crash point of ' + (crashPointFromHash(serverSeed, clientSeed) / 100).toFixed(2) +'x', '\t\tHash: ' + serverSeed);
}
var terminatingHash = genGameHash(serverSeed);
console.log('The final hash is: ', terminatingHash);
Using our chosen starting serverSeed, the hash terminating the chain is e68e26b9ae2090dde4be1e00af21c6d4ad271e76caa699ab8ff52f34033cb730. That is to say, the first game's hash played under the new provably fair scheme, when hashed will be e68e26b9ae2090dde4be1e00af21c6d4ad271e76caa699ab8ff52f34033cb730