HOW TO VERIFY PROVABLY FAIR KENO

The Three Inputs Behind Every Keno Draw

Provably fair Keno uses the same commitment scheme as every other original: three inputs feed a cryptographic function, and the drawn numbers are fixed before you play.

Before the draw, the casino generates a secret server seed and shows you only its SHA-256 hash — a sealed commitment it cannot change later. You supply (or accept and can change) a client seed, and a nonce counts up by one with every draw on the same seed pair. To settle the round, the casino runs HMAC-SHA256 with the server seed as the key and a message built from your client seed and nonce. The output bytes decide which numbers are drawn.

Because the server seed is locked by its hash before the draw and you control the client seed, neither side can change the drawn numbers after the fact without breaking the hash — which you can detect. For the full background on the commit-and-reveal model, see our complete guide to provably fair gambling and the general how-to-verify walkthrough.

How the Hash Seeds the Drawn Numbers

Keno draws a set of distinct numbers from a pool — on a standard Stake-style board, 10 numbers from a pool of 1 to 40. The trick is that the numbers must all be different, so the algorithm draws without replacement, exactly like a hash-seeded shuffle. Here is the derivation used by Stake-style implementations and mirrored by our verifier:

• 1
  Compute the HMAC. The casino calculates HMAC_SHA256(key = serverSeed, message = clientSeed:nonce:0) — 32 bytes of output, extended with :1, :2… if more bytes are needed.
• 2
  Turn bytes into numbers in [0,1). The bytes are read in groups of four, each becoming a fraction via byte1/256 + byte2/256² + byte3/256³ + byte4/256⁴. This produces a stream of random values between 0 and 1.
• 3
  Pick from the remaining pool. Start with the pool [1…40]. For each draw, multiply the next random value by the current pool size and floor it to get an index: index = floor(value × poolSize). Take the number at that index, then remove it from the pool so it cannot be drawn again.
• 4
  Repeat until 10 are drawn. Because each pick shrinks the pool by one, you always get 10 distinct numbers. The set is then usually shown sorted, but the order it was drawn in is what the algorithm produces.

Whether you hit depends on how many of your chosen spots appear in that drawn set, scored against the paytable. Every step is deterministic, so anyone with the same three inputs draws the same numbers.

Worked Example You Can Reproduce

The first digest is HMAC_SHA256("server-seed-demo-2026", "player-007:7:0"):

The first four bytes are a2 c3 57 f1 = 162, 195, 87, 241, giving the first value 162/256 + 195/256² + 87/256³ + 241/256⁴ = 0.6358. With a full pool of 40, the first pick is index floor(0.6358 × 40) = 25 → pool[25] = the number 26, which is then removed before the next pick.

That set of ten numbers was fixed the instant the server seed was committed — the same three inputs can only ever draw 2, 5, 6, 10, 14, 19, 20, 26, 31, 33. (The exact pool size and draw count vary by casino and your chosen risk; the method is identical.)

Where to Find Your Keno Seeds

The hardest part of verification is locating your seeds inside the casino. You must rotate (change) your seed pair first — the casino only reveals the unhashed server seed once it is retired, which is a security requirement so live results stay unpredictable. Then verification covers every draw made under that pair.

What This Proves — and What It Does Not

This is the honest part most Keno pages skip. A successful verification is powerful, but it has clear limits, and pretending otherwise would be dishonest.

Provably fair proves honesty, not generosity. Keno carries a built-in house edge regardless of how transparent the draw is — often one of the larger edges in the casino. Verification confirms the numbers that came out were the numbers the cryptography always pointed to; it does nothing to change your chance of matching spots, and it cannot turn a missed draw into a winning one. It also says nothing about whether the operator is trustworthy: a casino can implement flawless Keno and still stall withdrawals or run unlicensed. That is why we still weigh licensing and payout history in our provably fair casino reviews. For the full breakdown, see is provably fair actually fair?

Verify Other Games Too

Keno shares the same engine as every other original. Once you can verify a draw, the rest follow the same pattern — only the final mapping from hash bytes to result changes:

• •Plinko — the hash bytes become per-row left/right moves down the pegs into a bucket.
• •Limbo — the hash bytes become a single float, then a crash-style multiplier with the house edge baked in.
• •Dice, Crash & Mines — covered step by step in our how to verify provably fair results guide.

Frequently Asked Questions