Provably Fair Crash Verifier

🔢 How to check a round in 3 steps

Pick the game, paste the round’s hash and type the multiplier the game showed. Then press “Check this round” and the tool tells you if they match.

1. Pick the game you played: Aviator, Stake Crash, BC.Game Crash or bustabit.
2. Open that round in the game’s history and copy its hash. For Aviator, open your bet history, tap the green shield next to the round and copy the Combined SHA512 Hash. Paste it into the box, or press the Paste button.
3. Type the multiplier the game showed. You can skip this, but then the tool cannot say if it matches.

You never need to touch the salt. The tool fills it in and keeps it under “Advanced”. For BC.Game, it tries both the new salt and the older one, used before game 9,614,372, by itself.

It is fine to copy extra text around the hash. The tool pulls the hash out. If you paste a hash from a different game, it warns you.

Have the four Aviator seeds instead? Press the link under the box and paste them. You can paste all four into the first box in one go and the tool splits them. This also checks the Combined SHA512 Hash was made from those seeds.

Not sure what to paste? Press “Try an example” to see how it works first.

Want to check the maths? Press “Show the working” to see every sum, from the hash to the final multiplier. The verification guide shows where to find the hash, salt and seeds on each site.

Below the steps is one more check. For Stake Crash, BC.Game Crash and bustabit, the tool runs SHA-256 on your game hash. The answer should be the same as the previous game’s hash. For Aviator, if you pasted the four seeds, the tool runs SHA-256 on the server seed. The answer should be the same as the “Server seed SHA256” that Aviator shows before the round starts.

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✈️ How Aviator turns seeds into a multiplier

Aviator by Spribe makes each round from four seeds: the server seed and the client seeds of the first three players to bet, joined together and hashed with SHA-512.

Lots of people search for an Aviator SHA-256 formula. The round hash is not SHA-256. It is SHA-512. SHA-256 is only used for the server seed check described above.

How the tool turns the SHA-512 hash into an Aviator multiplier:

• ✅ Join the server seed and the three client seeds, in that order, with nothing between them.
• ✅ Run SHA-512 on that text.
• ✅ Take the first 13 characters and read them as a number.
• ✅ Divide that number by 2^52 to get r, between 0 and 1.
• ✅ Work out 0.97 / (1 - r), cut it to two decimals, and never go below 1.00x.

Worked example: Aviator round 12011757 from Spribe’s demo. The game showed 15.71x. The seeds were:

Server seed: MWsXhzU7IK77ENt3yPc52kwIhm1YHmhCfWE3rAKU
Client seed 1: QQ4YP4B6MTLjbpWdZwA1
Client seed 2: L8r29wcToZ1uMryPsZSQ
Client seed 3: A2xT4uIuL40751KWYXcR

With this 97% version, about 48.5% of Aviator rounds reach 2x and about 4% end at 1.00x. See the Aviator game page for how the game plays, and our page on Aviator rigging claims for what the numbers do and do not show.

📊 How Stake Crash works out the crash point

Stake Crash works out each crash point with HMAC-SHA256, using the game hash as the key and a fixed salt as the message, then reads only the first 8 characters of the result.

The source is Stake’s seeding post of 8 July 2019, which set out a chain of 10,000,000 SHA-256 hashes. The salt is the hash of Bitcoin block 584,500:

0000000000000000001b34dc6a1e86083f95500b096231436e9b25cbdd0075c4

The sum for Stake Crash goes like this:

• ✅ Take the first 8 characters of the HMAC. That is 32 bits.
• ✅ Read them as a number n, out of 2^32.
• ✅ Crash point = 2^32 / (n + 1) x 0.99.
• ✅ Never below 1.00x. The 0.99 is the 1% edge.
• ✅ Stake’s post does not say how it rounds. The tool cuts down to two decimals, as bustabit and BC.Game do.

Worked example, using the final hash from Stake’s 2019 seeding post:

78a9757d3be42b74a3f70239078ad9317125fe9ee630d5bdada46de963e56752

With a 1% edge, about 49.5% of rounds reach 2x and about 2% end at 1.00x. That holds for Stake Crash, BC.Game Crash and bustabit.

🧮 How BC.Game and bustabit work out the crash point

BC.Game Crash and bustabit both use HMAC-SHA256 with the salt as the key and the game hash, read as bytes, as the message, then take the first 13 characters of the result. That is 52 bits.

So Stake and BC.Game do not share a formula. Stake uses the game hash as the key and reads 8 characters. BC.Game uses the salt as the key and reads 13.

BC.Game Crash follows BC.Game’s own verify script on GitHub:

• ✅ r = n / 2^52, rounded to 9 significant figures.
• ✅ Work out 99 / (1 - r) and cut it down to a whole number.
• ✅ Divide by 100. Never below 1.00x.
• ✅ Since game 9,614,372, which started a new 20,000,000-round chain in September 2026, the salt is the hash of Bitcoin block 967,100. Games before that use the previous salt. The tool tries both salts by itself. The very oldest games used no salt, and this tool does not cover them.

bustabit follows the formula in bustabit’s 2018 seeding post. The steps are the same as BC.Game, with no 9-figure rounding of r. The salt is the Bitcoin block hash bustabit chose when version 2 launched in 2018:

0000000000000000004d6ec16dafe9d8370958664c1dc422f452892264c59526

Worked example with this bustabit sample hash:

5d07719b61b0abb6f1c3b17b1d69c838278f87f9b5e75077026e5fedf96c2eb2

🎯 What the tool cannot tell you

The provably fair verifier cannot tell you that the hash or seeds you pasted are the ones the site really used, so always copy them from the game’s own history panel, not from a screenshot or another website.

A match proves the round’s result came from that hash and that salt. A matching chain check proves the hash was set before your bet. Neither proves the salt was picked without knowing the chain. That is why Stake Crash took its salt from Bitcoin block 584,500, which had not been mined when Stake published its chain. bustabit did the same earlier, in 2015 and again in 2018. Provably fair explained covers why that order matters.

The Aviator check uses the 97% step Spribe does not publish. It matches real rounds, but it is not Spribe’s own written formula. JetX, Spaceman and other studio games use their own systems, and this tool does not check them. The provably fair ranking lists which other crash games can be checked.

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❓ Frequently asked questions

What if the multiplier does not match?

If the multiplier does not match, first check you picked the right game. Then check the hash belongs to that round, not the one before or after. Check you typed the crash point, not your cash out. You do not need to change the salt. If it still does not match, press “Copy a link to this check” and send the link to the site’s support. It opens the same check for them.

Is the Aviator hash SHA-256 or SHA-512?

The Aviator round hash is SHA-512. It is made from the server seed and three client seeds joined together. SHA-256 is only used to show the server seed’s check number before the round, labelled “Server seed SHA256”.

How do I turn an Aviator hash into a multiplier?

Take the first 13 characters of the SHA-512 hash and read them as a number. Divide by 2^52 to get r. Work out 0.97 / (1 - r), cut it to two decimals, and use 1.00x if it comes out lower. In round 12011757 that gives 15.71x, which matches the game.

Can I put this calculator on my own site?

Yes. Open the “Embed this tool on your site” box at the bottom of the tool and press “Copy code”. It loads crashedge.com/embed/provably-fair-verifier/ on your page.

Why is nothing sent to a server?

The check only needs the hash or seeds, the salt and a hashing function, and every modern browser can run SHA-256 and SHA-512 itself. So nobody else sees what you check or can change the result, and it works offline once the page has loaded.