JSFiddle - React, Tailwind, and code Playground
HTML
<form onsubmit="return false;">
<label for="gameHash">Game's Hash: (be sure to use a valid hash to get the real values)</label><br>
<input type="text" name="gameHash" id="gameHash" /><br>
<br>
<label for="gameAmount">Amount of game to show from this hash:</label><br>
<input type="number" min="1" step="1" name="gameAmount" id="gameAmount" value="100"/><br>
<button onclick="refreshTable();">Refresh Table</button>
</form>
<table id="hashTable">
<thead>
<tr>
<th>Game's hash</th>
<th>Crash</th>
</tr>
</thead>
<tbody id="tbody">
</tbody>
</table>
<script src="https://cdnjs.cloudflare.com/ajax/libs/crypto-js/3.1.2/components/core.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/crypto-js/3.1.2/components/sha256.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/crypto-js/3.1.2/components/hmac.js"></script>
CSS
table {
margin-top: 30px;
border-collapse: collapse;
}
table, th, td {
border: 1px solid rgba(0,0,0,0.3);
}
th, td{
padding: 5px;
}
JavaScript
function refreshTable(){
var hash = document.getElementById("gameHash").value;
var lastHash = "";
var amount = document.getElementById("gameAmount").value;
var tableBody = document.getElementById("tbody");
tableBody.innerHTML = "";
for(var i=0; i<amount; i++){
var gameHash = (lastHash!=""?genGameHash(lastHash):hash);
var gameCrash = crashPointFromHash((lastHash!=""?genGameHash(lastHash):hash));
var clr = gameCrash > 1.97 ? 'green': (gameCrash < 1.97 ? 'red' : 'blue');
tableBody.innerHTML += "<tr><td>"+gameHash+"</td><td style='background:" + clr + "'>"+gameCrash+"</td></tr>";
lastHash = gameHash;
}
}
function divisible(hash, mod) {
// 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;
}
function genGameHash(serverSeed) {
return CryptoJS.SHA256(serverSeed).toString()
};
function hmac(key, v) {
var hmacHasher = CryptoJS.algo.HMAC.create(CryptoJS.algo.SHA256, key);
return hmacHasher.finalize(v).toString();
}
function crashPointFromHash(serverSeed) {
// see: provably fair seeding event
var hash = hmac(serverSeed, '000000000000000007a9a31ff7f07463d91af6b5454241d5faf282e5e0fe1b3a');
// 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))/100).toFixed(2);
};