Provably fair crash games: what a published hash proves and what it does not

What a matching hash proves

• No swap after the bets. The result came from the seed committed before stakes were placed, so it could not be exchanged once the operator saw what was at risk.
• No tailoring to the table. On seeded titles the stop depends on the seeds only, not on the size of the stakes, the number of players or the moment anyone cashes out.
• Reproducibility. Where the mapping from hash to result is printed, the result can be recomputed from saved values, as the four-value walk-through shows with a worked example.

What it does not prove

• The house edge. A perfectly checkable game can carry any return the studio designs. Aviator's figure is 97% and Turbo Games gives 96% for Crash X and Aero; a matching hash confirms the game followed its own mathematics, not that the mathematics is generous. The edge is explained on the return-figure page.
• The casino's conduct. Identity checks, document deadlines and withdrawal caps sit in each operator's terms. A seed check says nothing about any of them; the operator fact boxes do.
• Games outside the scheme. A casino's seed page covers the games that publish seeds. It cannot reach inside a slot supplied by a third-party studio.
• The next round. Verification shows that a past round was not altered. It never predicts the next one, whose seed is still hidden behind its hash.

One provably fair crash round on a timeline

The scheme is easiest to hold in mind as four moments, each with its own thing for the player to do.

• Before the bets. Only the hash of the server seed is public; the seed is known to the operator alone. This is the moment to copy the hash.
• At the start. Client seeds join the server seed and the combination is hashed. From here the result is settled, so this is the moment to note which seeds went in.
• During the climb. Nothing enters the calculation any more: not the stakes, not the exits, not the number of players. There is nothing to record, only a round to watch.
• After the round. The server seed is disclosed, straight away in a per-round design like Spribe's, or at rotation in a seed-and-nonce design like Wolfbet's. Now the comparison becomes possible.

Miss the first moment and the last one loses most of its meaning, because a revealed seed has to be set against something you held before the bets.

Spribe's scheme, step by step

Spribe's fairness page, written for its games as a group, sets out the process in a handful of steps:

1. Step one belongs to the operator: a server seed made of 16 random symbols.
2. Before a round, the SHA256 value of its server seed can be read by the player: open «Provably Fair Settings» from the user menu and look for «Next server seed SHA256». The same window is where a player replaces their client seed.
3. Each player's side produces a client seed.
4. As the round opens, the client seeds are added to the server seed and the whole is run through SHA512.
5. The outcome is derived from the SHA512 value; Spribe notes that each game's mathematics varies slightly to fit the game.
6. When the round is over, a «provably fair» icon in the game history brings up the seeds, the joint hash and the outcome.

The page's own illustration, «AB» plus «CD» hashed as «ABCD», can be reproduced with any standard SHA512 tool, and the output matches Spribe's string. How the hash becomes a multiplier is covered on the stopping-value page.

Turbo Games: fixed before, checkable after

Turbo Games describes its crash titles in the same terms without printing the steps. For Crash X, released in March 2021, the studio ties each outcome to a cryptographic seed that players may inspect once the round is over. For Aero, released in August 2023, it goes further in wording: a hash of the seed is published before bets are taken, the seed follows at the end, no value is tweaked during the flight, and each round is described as verifiable by seed. Both pages list a return of 96% and a top value of ×999,999.

JetX: an RNG title for contrast

SmartSoft Gaming's JetX page states that the multiplier's height is random and offers no seed procedure. The title has other features on record, among them a return range of 96.2%–98.9%, two independent bets per round and automatic cash-out at a preset, but no published hash a player could compare. For an RNG title the assurance rests on the studio's description rather than on a value you can recompute yourself. The JetX guide covers the rest of the game.

What three casinos say about fairness

Five ranked casinos show crash studios on their provider lists, and three of them publish fairness statements of their own.

Bitsler states in its homepage copy that every game runs on provably fair technology. Read it as a statement about its own games; a third-party slot does not become seed-checkable because a casino says so. Bitsler lists Spribe and SmartSoft and names an in-house crash title, Crash Pro.

Rainbet describes its Originals as built on provably fair logic. For Case Battles and EOS Roulette it names blocks of the EOS blockchain as the randomness source, rather than a seed kept by the casino. Rainbet's provider list shows SmartSoft, whose JetX page describes an RNG.

Wolfbet has the most detailed page of the three. On 15 September 2026 it said that a hash of a freshly generated server seed is handed to the player after registration; that older bets open up for checking once a new server seed is generated from the «Session» menu, which exposes the previous one; that the player's own seed may be swapped whenever they like, starting a fresh chain; and that the nonce climbs with each bet and is reset whenever a new server seed takes over. Its FAQ, as read on 2 September 2026, offers two ways of replacing that seed: for each session, or for each bet ID. For its dice game it prints the complete procedure, built on HMAC-SHA256. Rotation gets its own treatment on the seed-rotation page.

One practical point follows from Spribe's own instructions: for a Spribe title, the check runs inside the game's history window, not through a casino's separate seed page.

Reading a provably fair crash claim

Before relying on the words «provably fair» on any screen, three questions sort a working scheme from a label. Is a hash of the server seed shown before you bet? Is the seed revealed afterwards, with the client seed and any nonce? And is the mapping printed, or at least a verifier offered, so that the result can be recomputed? A seeded title that answers all three gives you something to check; a label that answers none of them is only a word. Definitions of each term sit in the crash glossary.

Frequently asked questions