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How Provably Fair Actually Works (And How to Verify It Yourself)
Server seeds, client seeds and nonces explained in plain English, plus a step-by-step guide to checking any roll yourself.
Top Case Sites Team·· 1 min read
Every reputable case site and crypto casino advertises provably fair games. But what does that actually mean, and how can you check it yourself?
The three ingredients
- Server seed: a secret random value created by the site. Before you play, the site shows you its hash (a fingerprint), so it can't change the seed later.
- Client seed: a value you control (or one the site generates for you), so the site can't pick an outcome in advance.
- Nonce: a counter that goes up by one with every bet.
The result of each roll is calculated from all three, usually with HMAC-SHA256.
How to verify a roll
- Rotate (reveal) your server seed in the site's fairness settings.
- Hash the revealed seed with SHA-256 and check it matches the hash you were shown earlier.
- Plug the server seed, client seed and nonce into the site's verifier, or an independent one, and confirm the result matches.
Our giveaways are provably fair too
Every Top Case Sites giveaway publishes its server seed hash when it starts. The winner is drawn from that seed plus a public Bitcoin block hash that nobody knows in advance, and anyone can re-run the draw in their browser.
