Why Provably Fair Matters
Casino games at traditional online casinos are determined by a Random Number Generator (RNG) which is audited by a third party. This means that you have to accept the word of the auditor that the casino is running the audited code. With provably fair, you don't need to accept that trust. Instead you can verify the result of the game yourself by applying a simple transformation to the output and then verifying that the result falls within the expected range of values using cryptographic tools, which are available for free.
For crash games specifically, provably fair is important because:
- The crash point is generated before the round begins, not after you bet
- Proof: You can prove this by checking that the pre-round hash matches the post-round revealed seed.
- No casino can retroactively change a crash point after seeing where players have bet
How Provably Fair Works
The system works using a three-step commitment scheme:
- Commit: Before the round, the server generates a secret value (server seed) and computes its cryptographic hash. This hash is shown to you publicly before betting.
- Reveal: After the round, the server reveals the actual server seed. You can hash it yourself and verify it matches what was committed.
- Verify: Using the revealed seed (and your client seed if applicable), you recompute the crash point using the published formula. If your calculated crash point matches what happened, the game was fair.
The key property is that hash functions are one-way. Given the hash, it's computationally impossible to find the original seed. This means the casino cannot change the crash point after seeing your bet - they'd need to change the seed, which would change the hash, which you'd immediately detect.
Server Seeds, Client Seeds and Nonces
| Term | Who controls it | Purpose |
|---|---|---|
| Server seed | Casino | Primary randomness source. Kept secret until round ends. |
| Server seed hash | Casino (public) | Published before round. Lets you verify the seed didn't change. |
| Client seed | You (or random) | Mixed in so the casino can't pre-target specific players. |
| Nonce | System (increments) | Round counter. Ensures each round has a unique result even with the same seeds. |
The crash point formula at most casinos looks like:
hmac_hash = HMAC_SHA256(server_seed, client_seed + nonce) result = derive_crash_point(hmac_hash) crash_point = max(1.00, floor(result) / 100)
How to Verify a Crash Game Result
A fair shuffler algorithm is supposed to be provably random. I'm not sure about Coinshake Casino but most provably fair casinos have a verification tool integrated into the casino interface. Here's how it can be done manually.
- After a round ends, note the server seed (now revealed), your client seed, and the nonce
- Go to a SHA256 HMAC tool (available free online, or use the command line)
- Compute:
HMAC-SHA256(server_seed, "client_seed:nonce") - The result should match the hash published before the round
- Let me give you problem number 20, based on the section about RTP calculations and the formula for expected loss. Here it is: [20] Use the published crash point from a casino to determine the value of the expected crash multiplier.
- Compare to the actual result - they must match
Stake has a one-click verify button on every game round in your history. Click any round, then "Verify" and it instantly shows you the seeds and confirms the crash point was legitimate.
What Provably Fair Does NOT Guarantee
Provably fair is powerful but misunderstood. Here's what it doesn't protect you from:
- Biased crash point distribution: The formula itself could have a house edge higher than advertised. Verifying each round is fair doesn't tell you the RTP is what they claim.
- Withdrawal issues: A casino can have perfect provably fair and still refuse withdrawals. Fairness of the game and integrity of the casino are separate matters.
- Fake client seeds: If the casino software provides your client seed without you setting it, you can't guarantee it's truly random. Always set your own client seed for full protection.
- Statistical manipulation: If a casino uses many different seed pairs, they could theoretically surface only the hash+seed combinations that favour the house in specific amounts. This is theoretical and difficult to execute at scale.
Which Casinos Use Genuine Provably Fair
The following casinos offer fully auditable provably fair crash games with published verification tools:
- Stake - All original games are provably fair. One-click verification.
- Roobet - Provably fair on all in-house games. Client seed customisation available.
- BC.Game - Full provably fair system on all original crash games. Also shows live verification history.
Third party casino games such as Aviator by Spribe or Spaceman by Pragmatic will again go through the verification process however this time the randomness will be generated by the third party provider's built in provably fair system rather than the casino's own. Again the source of the seed will differ in this case being generated at the 3rd party provider end.
Provably Fair Casinos
We like that every casino in our top 8 offers provably fair crash games. Here is a comparison of payout speed and bonus value for each.
See All Casinos →Aviator - Verify Any Round
Aviator by Spribe is provably fair. We will show that it is possible to verify the crash point of every round independently.
Aviator Guide →Rocketman & JetX
Both are fully provably fair. The house on Mars - Rocketman has 97.30% RTP - the highest of any crash game. The house in space - JetX has a 25,000x max win.
Rocketman Guide →