Server Seed

Every provably fair roll is computed from three inputs: the server seed, your client seed, and the nonce. The server seed is the only input you cannot see during play, and it carries the bulk of the entropy, usually 256 bits generated by a cryptographic random number generator.

Because the roll function is deterministic, the moment a seed pair is locked, every future roll in that pair already exists mathematically. The server seed is what makes those rolls unpredictable to you; the hash commitment is what makes them unchangeable by the house.

SHA-256 is a one-way function: easy to compute forward, computationally infeasible to invert. Publishing the hash therefore reveals nothing useful about the seed while pinning the casino to it. Finding a second seed with the same hash (a collision) would require on the order of 2^128 attempts, far beyond any realistic computing power.

A worked shape of the flow: the site generates seed a7f3...c91b, shows you its hash 4be2...77d0, and you record that hash. Weeks later, after rotation, the site reveals a7f3...c91b. You hash it yourself; if the output is not exactly 4be2...77d0, the site swapped seeds and you have proof. This commit-then-reveal structure is the backbone of the whole provably fair scheme.

The hidden seed is not a trust compromise; it is what keeps the game a game. With the server seed in hand, anyone could evaluate HMAC-SHA256(server seed, client seed:nonce) for the upcoming nonce and know the result in advance. Secrecy during play and provability afterward are the two halves of the design.

This is also why you should treat a site that ever displays an unhashed active seed, or reuses a revealed seed, as broken. Once revealed, a seed is burned: honest sites generate a fresh one and show you the new hash immediately. When you audit past bets, do it on retired seeds with our provably fair dice verifier.

Rotation is player-triggered in the fairness settings of any legitimate dice site. The sequence: the active server seed is unsealed, a new seed is generated and its hash displayed, your nonce counter restarts at 0, and your bet history now shows the revealed seed against the rolls it produced.

Two checks follow every rotation: hash the revealed seed against the original commitment, then recompute a sample of rolls. A common mistake is never rotating at all, which leaves every bet unverifiable in practice since the active seed stays sealed. Verification discipline is a good filter when choosing where to play; the best bitcoin dice sites make rotation and old-seed lookup a one-click affair.