How to Verify a Blackjack Hand on 21z
Follow a blackjack hand from seed commitment to reveal and replay. Learn what pending reveal means and what verification can establish.
By 21z · Player guide
Start with the game ID
Open your hand history or the verified hands feed and select the hand you want to inspect. Keep its game ID. The verifier supports a game-ID lookup and manual inputs; select Blackjack as the game type.
A game ID identifies one recorded hand. A seed session can cover multiple hands, so the commitment transaction alone is not enough to distinguish your hand from the other hands in that session.
Understand the commitment and the nonce
Before real betting begins, the house anchors a hash of the secret server seed to Zcash. Your client seed and the hand nonce are used with that server seed to derive the deck. The nonce distinguishes hands that share the same seed session.
You can set a custom client seed before the first hand of the active seed session. After play begins, rotate to a new seed session to set another client seed. Keep the recorded inputs and fairness version together: changing an input means you are checking a different shuffle.
Wait for reveal, then verify
In session mode, finishing a hand does not reveal the secret seed. Finish any active game and use the seed-rotation control. Rotation reveals the previous session’s server seed so its completed hands can be checked.
If the verifier reports pending reveal, return after rotation and run the check again. Pending reveal is not a successful verification or a failed commitment check. Legacy hands use a different reveal lifecycle and can reveal at hand completion.
Read the checks in order
First, check that the revealed server seed hashes to the recorded commitment. Next, inspect the blockchain commitment result for real play. Finally, compare the reproduced cards, actions, outcome, and payout with the recorded hand.
For example, two hands from one session may share a server-seed hash and client seed but have different nonces. Verify each game ID separately. Reusing the first hand’s nonce for the second hand does not reproduce the second hand’s deck.
Know the limits of the result
A successful replay demonstrates consistency between the recorded inputs, the deterministic game logic, and the recorded result. It does not establish a profitable strategy, guarantee future results, or prove the operator can meet every withdrawal.
Demo hands use mock blockchain commitments. Use them to understand the process, but do not interpret a demo result as proof of a transaction on Zcash mainnet. If a real hand fails a check, preserve the game ID and the displayed result so the discrepancy can be investigated.