Checking a round
Aviator provably fair, step by step: what the hash proves
Aviator carries a provably fair label built on a commit-and-reveal scheme: a hash is published before betting opens, and the seed behind it can be checked afterwards. This page walks through what that check proves, and what it leaves untouched.
Aviator provably fair is the label Spribe puts on a specific claim: a round's outcome was locked in before anyone had staked on it, and a player can check afterwards that nothing was swapped along the way. It is a narrow claim about sequence and timing rather than a general promise about fairness, and understanding exactly what it covers matters more than the label itself.
Why the claim is narrow on purpose
A provably fair label is often read as a broad reassurance — “this game is fair” — when what Spribe actually publishes is closer to a receipt: a value committed before betting opens, and a way to check that value afterwards. The narrower a claim is, the easier it is to verify, and a commit-and-reveal scheme is narrow by design. It says nothing about return figures, nothing about a casino's own conduct, and nothing about any other game in the same lobby — only about whether one specific round's result existed before money moved. How that same narrow claim plays out across the operators actually compared here is covered on the the ranked list page.
How the Aviator provably fair scheme is built
Before a round opens, Spribe's system generates a server seed made of sixteen random symbols. Rather than publish the seed itself, it publishes a hash of that seed — the output of the SHA256 function run over it — inside a “Provably Fair Settings” panel, visible to the player before a single bet lands. A hash can be checked against a revealed seed afterwards, but it cannot be reversed to expose the seed in advance, which is the entire point of publishing it early: the commitment is locked in before money moves.
Players supply their own client seed as well, and at the moment a round starts the server seed and every client seed in that round are combined and hashed together, this time with SHA512, and the outcome for that round is derived from the resulting hash. Because both halves are fixed before betting opens, and combined in a fixed order once it does, neither side can adjust the outcome after seeing what has been staked. The round mechanics that outcome feeds into are covered separately on how Aviator works.
The order matters as much as the values themselves. A server seed hash goes up first, on its own, before a single client seed exists for that round. Only once betting has closed and every client seed for that round is known does the combination happen — meaning the studio's half was locked in before it could have been shaped by anything a player was about to contribute, and a player's half was added without any way to see what the studio's seed already contained.
The maths behind the commitment
A hash function takes an input of any length and turns it into a fixed-length string, and the same input always produces the same output. What makes a hash useful here is that the reverse direction does not work in practice: seeing the SHA256 hash published before a round gives no practical way to work backward to the seed that produced it. That one-way property is what lets Spribe publish the hash openly without giving away the seed itself, and it is what makes a later mismatch — a seed that does not reproduce the hash it was supposedly bound to — detectable rather than merely suspected.
How Aviator provably fair checks work after a round ends
Every finished round carries a “provably fair” icon in the game history, and following it lets a player pull the server seed, the client seed and the hash used for that specific round. Recomputing the hash from the revealed seed and comparing it against the one published beforehand confirms the seed was not swapped in between — the same check, repeated round by round, is what the label rests on. A player can also change their own client seed between rounds, which changes their half of the combination without touching the studio's committed seed.
Doing this by hand takes a moment: run the revealed server seed through the same SHA256 function used before the round, and compare the result character by character against the hash that was published in the settings panel before betting opened. A match confirms nothing was substituted; any difference at all — even a single character — would mean the published hash did not correspond to the seed later shown, which is precisely the kind of tampering a commit-and-reveal scheme is built to catch. Most players never run the check by hand, but the fact that anyone could is what gives the scheme its weight.
What the check proves
A provably fair check settles one thing precisely: the outcome existed before the bet did. If the server seed had been changed after seeing the size of a bet, the hash published beforehand would no longer match the seed revealed afterwards, and the mismatch would be visible to anyone who checked. That rules out the scenario players worry about most — a result chosen in response to how much money was riding on it.
What the check does not prove
A hash match says nothing about Aviator's 97% return figure, published separately from the fairness scheme, or about how any individual casino running the game behaves once money is involved. It does not cover a casino's own payout conduct, its withdrawal terms, or any game running on a different studio's engine entirely — a fairness label on one title says nothing about a slot or a table game sitting next to it in the same lobby. Because the seed hash is committed before a single client seed is even known, no outside method can see a round's outcome coming before it starts, which is why certain paid claims don't hold up.
RNG titles as a contrast
Not every crash-style title publishes a seed check the way Aviator does. Some run on a random number generator described only in general terms, with no equivalent commit-and-reveal step laid out on the page, which is a different kind of claim from a hash a player can recompute themselves. The presence or absence of a checkable seed is one of the clearer ways to tell what a studio is actually claiming, beyond the fairness label attached to a lobby tile — a comparison covered further on the studio reference page.
A page that says “RNG-based” without laying out a seed, a hash or a verification step is making a narrower claim than it might appear to: it is stating that an outcome was generated randomly, without giving a reader any independent way to confirm that afterwards. That is not the same as a false claim, but it is a claim that rests on trust in the studio's description rather than on anything a player can check for themselves, which is the exact gap a commit-and-reveal scheme is built to close.
A studio's claim and an operator's claim are not the same claim
A casino's own general fairness language, wherever it appears on a lobby page, describes that operator's positioning rather than the mechanism behind any one title running inside it. It cannot cover a game built by a studio that never published a checkable scheme in the first place, and it does not add anything to a scheme a studio already publishes in detail. Reading the studio's own fairness page for a specific title remains the only way to know what, if anything, can actually be verified for that title.
Two claims that sound similar in a lobby's marketing copy can rest on very different foundations underneath — one backed by a hash a player can recompute, the other resting on a general statement with nothing to check it against. Telling the two apart takes reading past the label to whatever mechanism, if any, the studio itself describes on its own page.