Key takeaways
- The game creates a secret server seed and publishes its hash before the round, like a sealed envelope.
- Seeds from players are mixed in, so the casino alone can't choose the result.
- After the round, the server seed is revealed. If its hash matches, the result wasn't changed.
- Provably fair proves the round wasn't tampered with. It does not remove the house edge.
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The problem provably fair solves
In an online game, the casino's server decides the result. Without some proof, you'd have to trust that it didn't look at your big bet and crash the round at 1.01x. Provably fair systems replace that trust with maths you can check.
How it works, step by step
- The server picks a secret seedA long random string, e.g.
9f2c…e71a. It will decide the crash point. - It publishes the hash firstThe game shows the SHA-256 hash of that seed before betting closes. A hash is like a fingerprint: it's easy to compute from the seed, impossible to reverse, and any change to the seed gives a completely different hash.
- Players add their seedsIn Aviator, the client seeds of the first three players to bet are mixed in, so even the casino can't fully control the input.
- The crash point is calculatedThe combined seeds are hashed again (SHA-512 in Aviator), and the crash multiplier is read from that result with a fixed formula.
- The server seed is revealedAfter the round, anyone can hash the revealed seed and compare it with the hash shown at the start. A match proves the seed, and therefore the result, was fixed in advance.
The sealed-envelope analogy
Imagine the casino writes the crash point on a card, seals it in a tamper-proof envelope and pins it to the wall before anyone bets. After the round, the envelope is opened. If the card says 1.84x and the round crashed at 1.84x, nobody could have changed it mid-round. The hash is that envelope.
Try a hash yourself
Type anything below and watch its SHA-256 hash. Change a single letter and the whole hash changes. That's why a published hash can't be "adjusted" later.
SHA-256 hash…
How to verify an Aviator round
- In the game, open the history (the clock icon or the bar of past multipliers).
- Tap a round, then the green shield / fairness icon.
- You'll see the server seed, the player seeds and the combined hash.
- Copy the revealed server seed into any SHA-256 tool (like the one above) and check that it matches the hash shown before the round.
- Spribe also links to an online calculator that turns the combined hash into the crash multiplier.
What provably fair does not prove
- It doesn't remove the house edge. The formula that turns hashes into multipliers includes the 3% edge.
- It doesn't make the casino trustworthy about payouts. Withdrawals, limits and account handling depend on the operator. Choose licensed sites.
- It doesn't let anyone predict the next round. Quite the opposite: it's precisely why predictors are scams.
Frequently asked questions
Does provably fair mean I will win?
No. It proves the result wasn't changed after you bet. The game still has a house edge (3% for Aviator), which is built into how crash points are distributed.
Can a provably fair game be hacked to predict results?
No. The server seed is secret until after the round, and working backwards from a SHA-256 hash to the seed is impossible with any existing technology. That's why predictor apps can't work.
Is JetX provably fair?
JetX uses an independently certified RNG rather than a player-verifiable seed system. It's tested, but you can't verify individual rounds yourself the way you can in Aviator.
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