How to verify a crash round with the seed, the nonce and the hash
A seed check needs four values, and one of them must be copied before you bet. This walk-through covers what to save, when to save it, how to compare hashes and what a missing value means.
To verify a crash round is to redo, after the fact, the calculation that produced its stopping value, and to confirm that the operator used the seed it committed to beforehand. Nothing about it needs special software: a SHA256 or SHA512 tool, the values the game shows, and the discipline to copy one of them at the right moment.
The steps follow two first-party descriptions opened on 15 September 2026. Spribe's provably fair page covers its games as a group; Wolfbet's fairness page lays out the seed-and-nonce model for the casino's own games and prints a complete procedure for its dice.
What a check needs, and when each value exists. The hash has to be saved before you bet, because nothing later reproduces it; the server seed only appears after rotation. With all four values the check is one hash and one comparison; with three of them it cannot be done at all.The fourteen sections
The server-seed hash, shown before the round. It is the operator's commitment, and a later comparison is only independent if you hold your own copy from before the stake went in.
The client seed that was active for the round. In Spribe's design the seeds of several players go into one round, and the history window lists them.
The nonce, in designs that use one. On Wolfbet it counts the bets made with the current pair of seeds.
The revealed server seed, available after the round in Spribe's games, or once the seed is retired on Wolfbet.
How to verify a crash round, step by step
Copy the hash before betting. In a Spribe game, open the user menu, choose «Provably Fair Settings» and copy the value labelled «Next server seed SHA256». On Wolfbet, the hash of the generated server seed is issued after registration.
Note your client seed. Change it first if you want a seed of your own choosing; Spribe offers this in the same settings window, and Wolfbet lets you change it whenever you like.
Note the nonce of the bet in a seed-and-nonce design. It starts again when the server seed changes, so write it down next to the hash it belongs to.
Get the server seed revealed. In a Spribe game, click the «provably fair» icon beside the round in its history list. On Wolfbet, create a replacement server seed from the «Session» menu, which exposes the old one.
Hash the revealed seed and compare. Run it through SHA256 and set the output beside the hash from step 1. Every character must match. A hexadecimal string means the same whether printed in capitals or in small letters, so compare without regard to case.
Recompute the combination. For Spribe, join the server seed and the players' seeds, hash the result with SHA512 and compare it with the combined hash in the history window. For Wolfbet's dice, run HMAC-SHA256 with the server seed as key and the client seed, an underscore and the nonce as the message.
Map the hash to the result with the game's own procedure or verifier, and compare with the number the round showed.
Step 5 is the heart of it. If the hashes match, the seed behind the round is the seed promised before the bets. Steps 6 and 7 then confirm that the displayed result really follows from that seed.
Rotation reveals the old server seed and, in the same act, ends any chance to check a round whose values were not saved. Both effects come from one step, so keep the hash, the client seed and the nonce before you rotate.
A worked example, computed from Wolfbet's dice procedure
The values below are invented for the example; this is not a real bet, and dice is not a crash game. It is here because Wolfbet's page prints the full mapping, which lets every step be shown with numbers.
Server seed: a1b2c3d4e5f60718. Its SHA256 hash begins b82efc46c073, the string a player would have copied in step 1.
Client seed: myclientseed. Nonce: 7.
HMAC-SHA256 with the server seed as key and «myclientseed_7» as the message gives a hexadecimal string beginning 5bef6c3997b8.
The first five characters, 5bef6, read as a hexadecimal number, equal 376,566. That is below 1,000,000, so it is used as it stands.
376,566 modulo 10,000 is 6,566; divided by 100, the roll is 65.66.
Had the game shown 65.66 for that bet, the check would be complete. Any difference, even in the second decimal, would mean either a copying error or a result that does not follow from the committed seed. Wolfbet's verification tab offers fields for the client seed, the nonce and the server seed for the same purpose.
Spribe's route from the game history
In a Spribe title such as the plane game from Spribe, the check starts from the round itself. Find it in the history and open the fairness window: it shows four items, namely the server seed, each player seed, the joint SHA512 hash and the result. Two comparisons are open to you: the server seed against the SHA256 value you copied before the round, and the joined seeds against the SHA512 value in the window.
Spribe keeps the function that turns the SHA512 hash into a multiplier inside each game, saying only that the mathematics differs slightly from title to title. That final step therefore rests on the game's own display. How a hash becomes a stopping value in general is traced in the maths behind the stop, and the scheme as a whole is set out on the fairness explainer.
Reproducing Spribe's illustration first
Spribe's page carries a small illustration that makes a good first exercise before a real round. It joins «AB» and «CD» into «ABCD» and prints the SHA512 value of that string, 128 characters opening with 49EC55BD83FC and closing with 5A33D9B. Hash «ABCD» in any SHA512 tool and the same string comes back. The illustration also prints a result of 25.00, but the step from hash to that number belongs to game mathematics Spribe does not publish, which is exactly the limit you meet with a real round.
Keeping a record you can use
A check is only as good as the notes behind it, and a plain text file per session is enough. At the top, write the date, the game and the server-seed hash copied before the first stake. For each round you may want to examine later, add how it appears in the history, the client seed in force, the nonce where the design uses one and the result the screen showed. When the seed is revealed, paste it under the hash it belongs to.
Copy and paste rather than retype. A single wrong character in a 64-character SHA256 string is enough to make an honest round look altered, and a single wrong digit in a nonce points the recomputation at a different bet.
When a value is missing
Without all four values you cannot verify a crash round, and it is worth being plain about why.
No saved hash. The revealed seed can still be hashed, but there is nothing you recorded independently to hold it against.
No nonce. In a seed-and-nonce design one server seed covers many bets; without the counter you cannot tell which result belongs to which bet.
No revealed seed. Until the seed is retired or the round is over, there is nothing to recompute. On Wolfbet that means generating a new server seed first; the seed-rotation page explains what that step changes.
No seed scheme at all. SmartSoft's JetX page credits the multiplier to random generation and gives no seed procedure; with no values to collect, a JetX round offers nothing to recompute.
What a match shows, and what it leaves open
A match shows that a finished round was not altered after the commitment. It never predicts the next round, and it says nothing about the return: Aviator's is 97%, so its house edge of 3% is untouched by any check, as the page on return figures explains. It also says nothing about a casino's identity checks or withdrawal caps, which live in its terms and in the operator fact boxes.
If a check fails, go back over the copying first. A trailing space, a dropped character or a seed from the wrong session changes the whole hash. If the values still disagree after that, keep them, note the round from the history, and put the question to the casino's support with the values attached. The vocabulary of seeds, hashes and nonces is collected in the crash glossary.
Frequently asked questions
Do I have to verify a crash round straight after it ends?
In a Spribe game the history window keeps the round's server seed, players' seeds, combined hash and result, so the check can come later, provided you saved the SHA256 hash beforehand. In a seed-and-nonce design such as Wolfbet's, bets under the current seed only become checkable once you generate a new server seed. What matters is the order: copy the hash first, compare later.
What tools do I need?
A SHA256 and SHA512 tool, available in most programming languages and in many offline utilities, plus an HMAC-SHA256 function for designs that use one, as Wolfbet's dice does. Beyond that, the values: the saved hash, the client seed, the nonce where the design uses one and the revealed server seed. Wolfbet's fairness page also offers its own verification fields for dice bets.
Can checking rounds improve my results?
No. A check confirms that a past round used the seed that was committed; it has no bearing on the next one, and it leaves the return unchanged. Aviator's stated return is 97% whether or not anyone checks a single round. Verification is a way to confirm the game kept its word, not a way to change what it pays.