The client seed is a value you supply that goes into the round's result calculation together with the server seed. In most games you can enter it yourself; in some it is generated automatically, but it must be changeable.
Why it is needed
Without your input the result would be decided by the casino alone. Even if it is honest, you could not prove it. The client seed makes the result a joint decision of two parties: neither can choose the outcome on its own.
In practice it also protects against a long-term pattern — the casino cannot pick a sequence of server seeds that works against your particular bets, because your seed is unknown to it.
How to use it
Enter something you chose yourself — any text will do. Change it from time to time: a rotation closes the old seed pair, reveals the server seed and lets you complete the check. See the verification steps described under hash.
Warning
If a game does not allow the client seed to be changed, it is not a complete provably fair scheme. The badge may be on the page, but the check cannot be finished — and that is exactly what most players never check.
What your seed actually changes
The result is computed from three parts: the server seed, your seed and the bet number (nonce). The casino showed you the hash of its seed before the game and is bound to it. You can choose your seed after seeing the hash, so the casino cannot pick the server seed to suit your input. That order is what gives your seed its value. If a game lets you change the seed without rotating the seed pair, check the game's description for how the nonce behaves before you draw conclusions about verification.
The myth of the "lucky seed"
With the same server seed, client seed and nonce the result is always the same, but a different seed gives results unrelated to the first. Every seed produces the same distribution, so there is no "lucky" seed and no strategy of picking a seed that changes the house edge. Changing the seed only changes the order of results, not the odds. Any promise that sells "better seeds" is empty.
Example: if 300 bets were made under one seed pair (nonce 0 to 299), after rotation you can recompute each of them and get the same number every time. That is the core of verifiability.
Practical steps
- Save the hash of the server seed before the first bet, then enter your seed. See the term provably fair for the explanation.
- Enter arbitrary text, not a password, a name or anything personal: the seed is displayed on the page during verification.
- Note the time you rotate the seed pair so you know which bets belong to which pair.
- Actually run a check on one round; the step-by-step guide is here. Without verification a seed is pointless, and it applies only to the casino's own originals games.
The seed pair logic is the same as the one described in Wikipedia: Commitment scheme. For the concept of random number generators see the freespin.ee glossary.