Blackjack

Provably fair

Verify fairness

The session's seed decides every card. Its hash was committed before the first hand; the seed is revealed when the session ends. Each round's cards come from HMAC-SHA256 keyed by the seed over the round's number and the bettor's own seed.

Seed hash

fec36ed4da6069b164d6c3f24001ee815c41f5bce34ab5c065e50306912e2bff

Seed

05b9988f4eb981d64f68cdea5f532cca14d3b3bf2844ebfd43a4248a54dccabf SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

1e7bed20381cac3610e8750ae510e09f

Commitment

Batch 49,579, Merkle root 58013c2abc701bfa2e252a6aa4d97ba03d3b5eabe18239821651931f23cf1cb1. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 5c1aaac97f1db38807db6684e35d6d3f42fc7a031bd769769536df5317015cc3
2. adb5a3f6dbee02bede8116362ddf8781e77b01903f554c91ab0c00d40b352457
3. 52d60e053c6d5f9f427944178853bd8498340a2948ba3c3ff096ba344c90c620

Checked: the seed hash proves into the root.

To check it yourself, take the session's proof:

1. Hash the seed as above and compare it with the seed hash; prove the seed hash into the root with the Merkle path (keccak256, as for every match).
2. For each round: round seed = HMAC-SHA256(key = seed, "degen.house.round.v1" ‖ 0x00 ‖ u64be(length of the bettor's seed) ‖ bettor's seed ‖ u64be(round)).
3. Key ChaCha20 (RFC 8439, zero nonce) with the round seed and read little-endian 64-bit words; a card is the next word below 2⁶⁴ − 1 − ((2⁶⁴ − 1) mod 52), modulo 52.
4. Replay the round's actions with the game's rules: the cards and the payout must match.

The replay plays every hand rebuilt this way on the server from the same data, and marks any that does not rebuild as recorded.