Cups uses a Provably Fair system to ensure that every round is transparent, independently verifiable, and cannot be altered after betting begins.
Each game result is generated using three values:
Server seed – generated by the server and committed to before the round starts by displaying its SHA-256 hash.
Client seed – your unique client seed.
Nonce – an incrementing number that ensures every round produces a unique result.
Because you receive the hashed server seed before placing your bet, the server cannot change the outcome after the fact without invalidating the previously displayed hash.
The winning cup is determined using the following calculation:
hmac = HMAC_SHA256(serverSeed, clientSeed:nonce)
raw = parseInt(hmac[0..8], 16)
winningCup = raw % numberOfCups
After the server seed is revealed (when the seed pair is rotated), you can verify previous game results in the Verify tab. Simply compare the revealed server seed with its previously displayed hash and repeat the calculation to confirm that the winning cup was generated fairly.
This system ensures that every Cups round is random, transparent, and cannot be manipulated by either the player or the casino after the server seed has been committed.