Fairness

Provably Fair Keno

Keno draws 10 numbers from a pool of 40. Pick your numbers before the draw, and your payout scales with how many you match.

Verify Game Fairness

The algorithm uses selection without replacement - each number is removed from the pool after being drawn, ensuring no duplicates.

The Algorithm

// Step 1: Generate 10 floats (needs 40 bytes = 2 hash rounds)
const floats = [];
for (let round = 0; round < 2; round++) {
    const message = `${clientSeed}:${nonce}:${round}`;
    const hash = HMAC_SHA256(serverSeed, message);

    // Extract floats from this round's hash
    for (let i = 0; i < 8 && floats.length < 10; i++) {
        const bytes = hash.slice(i * 4, i * 4 + 4);
        let float = 0;
        for (let j = 0; j < 4; j++) {
            float += bytes[j] / Math.pow(256, j + 1);
        }
        floats.push(float);
    }
}

// Step 2: Select numbers without replacement
const pool = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40];
const result = [];

for (let i = 0; i < 10; i++) {
    const index = Math.floor(floats[i] * pool.length);
    result.push(pool.splice(index, 1)[0]);
}

How It Works

1. Generate floats - Keno needs 10 random numbers. Since each hash provides 32 bytes and each float uses 4 bytes, a single hash can produce 8 floats. Keno requires 2 hash rounds (rounds 0 and 1) to get all 10 floats.
2. Create the pool - Start with numbers 1 through 40 in an array
3. Selection without replacement - For each of the 10 picks:
   • Multiply the float by the current pool size
   • Floor to get an index
   • Remove and record the number at that index
   • The pool shrinks by 1 each time

This method ensures every number has an equal chance of being selected, and no number can be drawn twice.

Example

Given these inputs:

• Server Seed: c5e7146c5863d7d647c93ffe7d4ec13fffbb7311108fab0c067d97bcc2b32d55
• Client Seed: LuckyClientSeed777
• Nonce: 1

Keno needs 10 floats (40 bytes), requiring 2 hash rounds. The floats extracted:

Selection without replacement:

The 10 selected numbers: 23, 12, 15, 21, 16, 26, 28, 13, 10, 20.

Verify your bets by selecting the "My Bets" tab at the bottom of the page while playing, then click on the bet you want to verify. For older bets, find them in your Bet History.