What Does Provably Fair Mean?
Provably fair means you can mathematically verify that a game outcome was determined fairly, without trusting the casino. Before each round, the server commits to a hashed seed. After the round, the full seed is revealed so you can recalculate the result yourself. If the recalculated result matches what you saw, the game was fair.
How Rookie Implements It
Rookie uses HMAC-SHA256(server_seed, client_seed:nonce) to generate random values for every game. You control the client seed (change it anytime), and the nonce increments with each bet. The server seed hash is shown to you before play, and the raw server seed is revealed when you rotate it — proving that every past bet was generated from the committed seed.
The Verification Process
Visit the Fairness page on Rookie to verify any past round. Enter the server seed, client seed, nonce, and game parameters. The page will recalculate the result using the same HMAC-SHA256 algorithm and show you the step-by-step derivation. If the result matches, the round was provably fair.
Why This Matters
Traditional online casinos use opaque random number generators audited by third parties. You have to trust both the casino and the auditor. Provably fair eliminates that trust requirement entirely — the math is public, repeatable, and verifiable by anyone. It's the gold standard for fair online gaming.