Commit-reveal is a genuinely strong guarantee, and it is routinely oversold. Here is precisely what it establishes, what it leaves open, and why a serious platform needs two more layers of evidence besides.
Every online casino asks players to trust that the outcome was not chosen after they bet. Historically the only answer was institutional: a licence, a certificate, an auditor's name in the footer. That works, but it is trust by reference — the player is trusting a chain of organisations rather than checking anything.
Provably fair replaces one link in that chain with mathematics. It lets a player verify, without trusting the operator or the game studio, that the result they received was fixed before they committed money.
The mechanism is a cryptographic commitment. Before the round, the server generates a secret server seed and publishes its SHA-256 hash. A hash is one-way: the player learns nothing about the seed, but the server can no longer change it without the hash failing to match later.
The player contributes a client seed — often just a value their browser generates. This is the part people miss, and it is the part that matters: because the outcome depends on both seeds, the server cannot pick a server seed that produces a specific result, since it does not control the client's half.
A nonce, a per-round counter, is combined with both seeds so a single seed pair yields a distinct verifiable outcome for every round rather than repeating.
After the round, the server reveals the seed. The player hashes it, checks it matches the commitment published beforehand, and recomputes the outcome from the two seeds and the nonce. If both checks pass, the result was determined before the bet and was not altered.
Commit-reveal establishes exactly one thing, and establishes it strongly: the outcome of this specific round was fixed before you bet, and was not changed afterwards. No trust in the operator is required to check it.
That is a real guarantee and it eliminates the single most damaging category of cheating — the server looking at the bet and then deciding the result.
It does not prove the game's RTP. A game can be perfectly provably fair and still pay 80%. Commit-reveal verifies that the outcome came from the declared seeds; it says nothing about the distribution those seeds are being fed into. That is a property of the math model, and it needs separate evidence.
It does not prove the RNG is sound. If the seed generation is weak or predictable, every round can be individually verifiable and collectively exploitable.
It does not prove the game you played is the game that was certified. That requires tying each round to a specific game build and persisting it.
Anyone presenting provable fairness as a complete fairness story is either confused or hoping you are.
Fairness in a regulated context needs all three of the following, and they answer genuinely different questions.
NIST SP 800-90A Rev. 1 HMAC-DRBG with SHA-512 at 256-bit security strength, multi-source entropy, and continuous statistical self-tests based on NIST SP 800-22. Answers: are the numbers actually unpredictable?
Every RTP variant verified across 10,000,000 fixed-seed Monte Carlo rounds, landing within ±0.5% of the theoretical model, with the written model shipped alongside the output. Answers: does the game pay what it claims?
SHA-256 commitment before the bet, seed revealed after, verifiable by the player on a public page. Answers: was this specific round decided before I played?
No — the two are unrelated. Provable fairness verifies that a specific round's outcome was fixed before the bet. RTP is a property of the math model and requires separate evidence, normally a written model plus simulation output.
Not by altering a committed outcome — that breaks the hash check. The remaining risks lie elsewhere: weak seed generation, or a game build that differs from the certified one. Those are addressed by RNG standards and by tying rounds to versions.
Because it removes the server's ability to choose an outcome. If only the server contributed entropy, it could generate many candidate seeds and commit to whichever produced a favourable result.
Yes — SHA-256 commit-reveal runs on every real-money round across all five titles, with a public verification page.
Book a technical demo — we will walk through the math models, the simulation output and the certification dossier directly.