Provably fair is a system that lets you check, after the fact, that a game result was fixed before you placed your bet and was not changed afterwards. The casino commits to a hidden server seed by showing its hash, you add your own client seed, and a counter called the nonce numbers each bet; once the seed is revealed, anyone can recompute the result. It proves a round was not altered. It does not prove the game pays well.
The three ingredients: server seed, client seed, nonce
- Server seed: a long random string generated by the casino. Before you play, you only see its SHA-256 hash, a fingerprint that cannot be reversed and that changes completely if a single character of the seed changes.
- Client seed: a string on your side. Most in-house games let you edit it whenever you like. Since the casino cannot know it in advance, it cannot prepare outcomes around it.
- Nonce: a number that starts at 0 or 1 and rises by one with each bet made on the same seed pair. It is why bet 57 and bet 58 give different results from identical seeds.
The result comes from a keyed hash, usually HMAC-SHA256, computed from the server seed and the string client seed:nonce. The output is a hexadecimal string, which the game converts into a number, then into a dice roll, a crash multiplier or a Plinko path. The conversion formula is part of what the operator publishes.
Verifying a dice roll in five steps
- Before betting, copy the hashed server seed shown in the game’s fairness panel.
- Replace the default client seed with any string of your choice.
- Play, then note the nonce and the result of the bet you want to check.
- Rotate the seed pair. The casino now reveals the previous server seed in plain text.
- Hash the revealed seed with any SHA-256 tool and compare it with the hash from step 1. If they match, run HMAC-SHA256 with that seed, your client seed and the nonce, then apply the published conversion. The number must equal your roll.
Many players stop at the hash comparison. That only proves the seed was not swapped mid-session. The full recomputation is what proves the roll itself. Both checks take minutes, and you only need to run them once to know the mechanism is genuine.
How crash games use a hash chain
A crash round is shared by everyone at the table, so one player’s client seed cannot drive it. Crash originals usually rely on a chain instead. The operator generates a long sequence of hashes in advance, each one obtained by hashing the next, and plays them in reverse order. When a round’s hash is revealed, hashing it gives the hash of the previous round, which you can compare with what was shown. The multiplier is derived from the round hash by a formula with the house edge built in. Since the whole chain existed before the first round, the casino cannot hand a low multiplier to a round where heavy bets came in.
Aviator and the first three bettors
Aviator, Spribe’s crash game, combines the operator’s server seed with the client seeds of the first three players to bet in each round. Those four inputs fix the result, and the round details display all of them, so no single party, the casino included, controls the multiplier alone. Spribe appears in the provider lists of Vavada, Drip and Lex. That matters for readers in France: BC.Game does not open accounts there, while Vavada accepts French residents and carries Spribe titles.
What provably fair does not prove
- The house edge. A provably fair dice game set at a 1% edge still keeps 1% of turnover over time. Verification shows the round was not rigged, not that the odds favour you.
- Third-party slots. Pragmatic Play, Evolution or Hacksaw titles run on the providers’ certified RNGs. At BC.Game, Wild.io and BitStarz, only the in-house originals carry seeds you can check.
- The cashier. A verified round says nothing about withdrawal speed, limits or KYC. Those come from the terms and the licence.
For the slots that sit outside provably fair, fairness is checked another way. The game should come from the provider’s own servers, with its certified RTP displayed in the info panel; iWild shows RTP per game. Independent spot checks help too: casino.guru’s Gamecheck found no fake games in samples taken at Vavada, Katsubet and Drip. A slot whose RTP cannot be found anywhere is the one to skip.
BC.Game shows that split clearly. Its originals (Crash, Plinko, Limbo, Dice, Tower Legend) publish verifiable seeds. Its licence comes from Anjouan, obtained around late 2024 after the brand’s former Curaçao entities went through bankruptcy and Curaçao moved to revoke the licence. The hash answers the first question, the licence file the second; our full BC.Game review covers both, and the regulator side is unpacked in Curaçao vs Anjouan licences.
Where to play provably fair originals
| Casino | In-house provably fair games | Licence | Crypto payout | France |
|---|---|---|---|---|
| BC.Game | Crash, Plinko, Limbo, Dice, Tower Legend | Anjouan ALSI-202410011-FI1 | Instant to ~1 h | Not accepted |
| Wild.io | About 20 Wild Originals (crash, Plinko, Mines, Keno) | Anjouan ALSI-202504044-FI2 | ~10 min | Not accepted |
| BitStarz | About 18 Originals (Crash, Plinko, Dice) | Curaçao OGL/2024/165/0185 | ~10 min | Not accepted |
| iWild | Dice, Plinko, Keno, Mini Roulette, HiLo | Curaçao OGL/2024/758/0228 | Up to 72 h | Not accepted |
| Vavada | No originals; Spribe titles | Curaçao OGL/2024/252/0153 | Within 24 h | Accepted |
BC.Game also runs its originals and a sportsbook on one wallet, opens accounts in XOF and XAF, and none of the 14 French-speaking African countries we track appears in its exclusion lists. For a reader in Abidjan, Douala or Dakar who wants verifiable crash and dice, it is the most complete option in this table; our guide for African players lists the others. Wild.io is the alternative with automatic payouts in about ten minutes, set out in the Wild.io review. BitStarz, online since 2014, holds the only Curaçao licence of the three, and the BitStarz review weighs it against the two Anjouan brands.
Check one round, then play
Set a custom client seed before your first bet, keep the hashed server seed, and verify one round after rotating. After that, the decision rests on the cashier and the bonus. BC.Game pays four monthly deposit bonuses from 180% to 360%, starting at a $5 deposit, credited as locked rakeback rather than wagered bonus money; the mechanics are on the BC.Game deposit bonuses page, and the comparison with cashback is in rakeback vs cashback. Fund in BTC or USDT with the network you know, using our Bitcoin casino payments guide if you start from scratch. Then open your account through the BC.Game review and run your first verification on a minimum stake.
Tom compares international online casinos on the details that decide a cash-out: wagering maths, withdrawal caps and delays, accepted countries and the cashier. His reviews score each brand against its own terms, licence and payment limits, and name the exact point where those documents leave a gap.
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