Nonce
A bet counter that goes up by one every time you bet on the same seed pair, so each bet gets its own result.
The nonce is just your bet counter in a provably fair setup. As long as the server seed and client seed don't change, it starts at 0 (some casinos start at 1) and goes up by one each time you bet.
What it's for
Without it, the same pair of seeds would give you the exact same result every bet. The nonce makes every bet different while the whole sequence stays locked to the seeds, so you can rebuild any bet you placed later on.
What to look out for
- Every bet should push the nonce up by exactly one. No skips, no repeats. A gap can mean bets got dropped or replayed, and our audits check for that.
- Figure out if the site starts at 0 or 1. Being off by one is enough to make every check fail.
Real-life example
You roll dice four times and your history shows nonces 0, 1, 2 and 3. To check roll number three, you run HMAC-SHA256 with the server seed as the key and "client seed:2:0" as the message, turn the bytes into a float, then the float into your roll.