Duel Casino Review

2025

1// Code written in JavaScript
2
3// User input values
4const drandSeed = '';
5const serverSeed = '';
6
7// Converts a hex string (e.g. "deadbeef") into a Uint8Array of bytes
8function hexToBytes(hex) {
9  const bytes = new Uint8Array(hex.length / 2);
10  for (let i = 0; i < bytes.length; i++) {
11    bytes[i] = parseInt(hex.slice(i * 2, i * 2 + 2), 16);
12  }
13  return bytes;
14}
15
16// Converts a hex-encoded public seed into a UTF-8 string
17function hexToUtf8String(publicSeed) {
18  const bytes = hexToBytes(publicSeed);
19  return new TextDecoder('utf-8').decode(bytes);
20}
21
22// Converts a Uint8Array of bytes back into a hex string (e.g. [222, 173, 190, 239] → "deadbeef")
23function bytesToHex(bytes) {
24  return Array.from(bytes)
25    .map((b) => b.toString(16).padStart(2, '0'))
26    .join('');
27}
28
29// Concatenates multiple Uint8Arrays into a single Uint8Array
30function concatBytes(arrays) {
31  const totalLength = arrays.reduce((sum, a) => sum + a.length, 0);
32  const result = new Uint8Array(totalLength);
33  let offset = 0;
34  arrays.forEach((a) => {
35    result.set(a, offset);
36    offset += a.length;
37  });
38  return result;
39}
40
41// Computes a HMAC-SHA256 using the Web Crypto API
42// keyHex: hex-encoded key (e.g. server seed)
43// message: Uint8Array to be signed
44async function generateHMAC_SHA256(keyHex, message) {
45  const keyBytes = hexToBytes(keyHex);
46
47  // Import raw key for HMAC use
48  const cryptoKey = await crypto.subtle.importKey(
49    'raw',
50    keyBytes,
51    { name: 'HMAC', hash: 'SHA-256' },
52    false,
53    ['sign'],
54  );
55
56  // Generate HMAC signature
57  const signature = await crypto.subtle.sign('HMAC', cryptoKey, message);
58  return bytesToHex(new Uint8Array(signature)); // Return signature as hex
59}
60
61// The actual fairness verification function
62const validateCrashResult = async (serverSeed, drandSeed) => {
63// Prepare input message for HMAC: public seed + nonce
64  const NONCE = 0;
65  const randomness = hexToUtf8String(drandSeed);
66  const message = new TextEncoder().encode(`${randomness}:${NONCE}`);
67
68  // Compute HMAC hash
69  const hash = await generateHMAC_SHA256(serverSeed, message);
70
71  // Use first 4 bytes of hash for entropy
72  const value = parseInt(hash.slice(0, 8), 16);
73
74  const MAX = 2 ** 32;
75  const houseEdge = 0.001;
76  const result = (MAX / (value + 1)) * (1 - houseEdge);
77
78  return Math.max(1.0, result);
79};
80
81// Run the validateCrashResult function if input values are provided
82if (serverSeed && serverSeed.trim() !== '' && drandSeed && drandSeed.trim() !== '') {
83  validateCrashResult(serverSeed, drandSeed).then(result => {
84    console.log("Crash result:", result + "x");
85  });
86} else {
87  console.log("Please fill in the drandSeed and serverSeed values.");
88}