Aviator Provably Fair: How to Verify a Round Yourself (SHA-512 Walkthrough)

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Author: Victor Hale | Last updated: October 2026

“Provably fair” is the phrase on every Aviator lobby and almost nobody checks what it means. It means this: the crash point of each round is fixed by a cryptographic hash before bets close, the inputs are published after the round, and you can recompute the result yourself. Below is the mechanism step by step, the formula that turns a hash into a multiplier, a worked example from a real round, and a tool that does the arithmetic for any round you paste in.

Provably fair in one table
Server seed	Generated by Spribe before the round; its SHA-256 fingerprint is shown in advance
Client seeds	Three, from the first three players to bet in that round
Combined hash	SHA-512 of server seed + client seed 1 + 2 + 3 (no separators)
Multiplier	From the first 13 hex characters of the hash, 3% edge built in
What you can check	That the hash matches the seeds and that the multiplier matches the hash
What it does not promise	A win. RTP is 97% by design

The in-game panel: what each line means

Open the fairness panel for any finished round (the shield icon next to the multiplier in the history ribbon, or the three-dot menu depending on the lobby). You will see:

• Server Seed — a random string Spribe generated before the round. During the round only its SHA-256 hash was visible (menu → Provably Fair Settings → “Server seed SHA256”); after the round the seed itself is revealed.
• Client Seed 1, 2, 3 — strings generated on the devices of the first three bettors. Their player names are shown next to them. Whatever three seeds the panel lists are the three that went into the hash.
• Combined SHA512 Hash — the hash of all four seeds concatenated.
• Hex — the first 13 characters of that hash.
• Decimal — the Hex value as a number.
• Result — the multiplier of the round.

Everything below the seeds is arithmetic you can repeat.

Step by step: from four seeds to the multiplier

Step 1 — commit. Before bets open, the server seed exists and its SHA-256 fingerprint is published. The seed cannot be changed afterwards without the fingerprint failing to match.

Step 2 — client seeds. The first three bets of the round carry client seeds from the players’ devices. Nobody — not Spribe, not the casino — knows all four inputs before bets are placed, because three of them do not exist yet.

Step 3 — hash. Concatenate: server_seed + client_seed_1 + client_seed_2 + client_seed_3. Hash the string with SHA-512. The output is 128 hexadecimal characters.

Step 4 — take 13 characters. The first 13 hex characters are 52 bits — a number between 0 and 2⁵² − 1. Call it h.

Step 5 — formula. Under the standard reconstruction of Spribe’s formula (verified against published rounds, including the example below):

e = 2^52
x = h / e                       (a number between 0 and 1)
result = max(1.00, floor(0.97 / (1 − x) × 100) / 100)

Equivalent integer form: floor(97 × e / (e − h)) / 100. The 0.97 is the RTP; it is what makes the long-run return 97% and the house edge 3%.

Step 6 — compare. If your SHA-512 matches the panel’s Combined Hash and your result matches the panel’s Result, the round was computed from the seeds shown. That is the entire guarantee — and it is a strong one.

Worked example: a real round we verified ourselves

Round 12011757 in Spribe’s official demo, 5 October 2026, 07:13 UTC+3. We copied the four seeds from the panel and recomputed everything:

Step	Value
Server seed	MWsXhzU7IK77ENt3yPc52kwIhm1YHmhCfWE3rAKU
Client seeds (players 1, 2, 3)	QQ4YP4B6MTLjbpWdZwA1 · L8r29wcToZ1uMryPsZSQ · A2xT4uIuL40751KWYXcR
SHA-512 of the four seeds concatenated	f031b1d726d1f94f8122a435bf859442a02d303c94be173ae6123a21f32e029dcaa8ed70d35e37778e2bb89… — identical to the panel’s Combined Hash
First 13 hex characters	f031b1d726d1f
Decimal	4 225 539 643 698 463
x = h ÷ 2⁵²	0.9382583
0.97 ÷ (1 − x)	15.7106…
Floor to two decimals	15.71× — the panel showed 15.71×

We ran the same check on two more rounds from the same session: round 12011729 (hash prefix 0767bac5a6b56, raw value 0.9989 → clamped to 1.00×, exactly what the panel showed for that instant crash) and round 12011774 (c7f2990f58025 → 4.43×). Three rounds, three exact matches, no rounding tricks.

The commitment also checks out. Before round 12011774 started, the Provably Fair Settings dialog showed the next server seed’s SHA-256 as 13367728ac65bb2c047cfe7a8635ee798c1f9f69085633493b96fe9eec98678d. After the round, the panel revealed the server seed b2poF8w6Kd5UaKm2hMnFeUm8YTxYKekG5IK9vrPa. SHA-256 of that seed is the published fingerprint, character for character. The seed existed, and was locked, before anyone placed a bet.

Verify a round with the hash tool

Paste the four seeds exactly as shown in the panel (no spaces added, no characters dropped). Optionally paste the Combined Hash to compare. The tool computes SHA-512 in your browser — nothing is sent anywhere. The “Load the worked example” button fills in round 12011757 so you can watch the hash reproduce before you try your own round.

If the hash matches but the multiplier differs by 0.01, check that the panel's result was floored, not rounded; the game truncates. If the hash does not match, the most common causes are a copied space, a missing character, or seeds pasted in the wrong order — the order is server seed, then client seeds 1, 2, 3 as listed.

What the formula tells you about the odds

Because x is uniform between 0 and 1, the probability that a round reaches a multiplier m is simply 0.97 ÷ m:

Multiplier	Chance the round reaches it
1.20×	80.8%
1.50×	64.7%
2.00×	48.5%
5.00×	19.4%
10.0×	9.7%
100×	0.97%
1 000×	0.1%

And the instant crash: the formula floors to 1.00× whenever 0.97 ÷ (1 − x) is below 1.01, which happens for roughly 4% of rounds. Those are the rounds where the plane leaves before any cash-out can fire. Every strategy on the strategy page is built on this table.

What provably fair guarantees — and what it does not

It guarantees:

• The crash point was fixed before bets closed and could not be changed afterwards.
• The result follows from inputs you can see, by arithmetic you can repeat.
• Nobody, including the operator, knew the multiplier before the first three bets existed. This is also why predictors and signal channels cannot work.

It does not guarantee:

• That you win. The 0.97 in the formula is the house edge; fairness here means "as advertised", not "favourable".
• That the casino pays. Withdrawals, verification and limits are the operator's business, governed by its licence, not by the game's math.
• That a lobby is genuine. A fake "Aviator" on a scam site can show a panel that does not verify. If the hash tool says no, the game is not Spribe's.

Common misunderstandings

• "The casino sets the crash point." It cannot. It does not hold the server seed and it does not control the client seeds.
• "The server seed is reused, so patterns exist." A new seed is committed every round; the fingerprint changes each time.
• "If I bet first, my client seed gives me an edge." Your seed is one of four inputs to a hash. Changing it changes the output unpredictably, in no direction you can choose.
• "Provably fair means 100% RTP." It means the published 97% is enforced by the formula, not that the edge is zero.

Where to play Aviator with a verifiable panel

The provably fair panel is part of Spribe's build and appears at every licensed operator carrying the game. Choose the casino for its cashier and limits; the fairness is the same everywhere.

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Frequently asked questions about Aviator provably fair

Can I verify a round without playing?

Yes. Open any finished round in the panel of a demo or live lobby, copy the seeds and paste them into the tool above. No account is needed to read the panel in demo mode.

Which hash function does Aviator use?

SHA-256 to publish the server seed's fingerprint before the round, SHA-512 to combine the four seeds into the round hash.

Is the formula official?

Spribe publishes the mechanism (seeds, hash, panel) but not a line of code. The formula here is the community reconstruction that reproduces published rounds, including the example above. If you find a round it fails on, send us the seeds.

What if fewer than three players bet?

The panel always lists three client seeds for a finished round. Use the three it shows, in the order shown; verification works the same way.

Does provably fair mean I cannot lose?

No. It means the 97% RTP is enforced by math you can check. Over time you lose 3% of turnover regardless of strategy.

Why does my computed multiplier differ by 0.01?

The game floors (truncates) to two decimals rather than rounding. Use floor in your own calculation, as the tool does.

Can a predictor use the server seed hash?

No. SHA-256 cannot be reversed to recover the seed, and the three client seeds do not exist until bets are placed.

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Play responsibly. 18+. Gambling should be entertainment, not income. If it stops being fun, seek help at BeGambleAware.org or GamCare.

Sources and method

The Aviator provably fair panel and the in-game "What is Provably Fair" text (Spribe build, official demo, 5 October 2026): Spribe states that the round result is generated from four participants — the operator's server seed, whose SHA-256 is published before the round, and the client seeds of the first three bettors — merged and hashed with SHA-512. Rounds 12011729, 12011757 and 12011774 were recomputed by us on 5 October 2026, including the SHA-256 commitment check; the multiplier formula is the community reconstruction (first documented by gamblingcalc.com), which reproduced all three rounds exactly. The verification tool runs SHA-512 locally in the browser via the Web Crypto API. Screenshots on this page were taken by us in the official demo.

Keep reading

• Aviator predictor apps and hacks: why none can work
• Aviator strategy: what changes your risk and what does not
• Aviator demo and session simulator
• Spribe — the studio behind Aviator