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

a04385b74694c35ebc9e353bba5810bdc64057be10791c986900653c6952e0b2

Seed

86f6255f5ddbabd135bf230e8fd76f3f424d3c3e01f700d85896ab08527ca961 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

e5939bfdab93ef9135c3caa40ad7bbb6

Commitment

Batch 72,629, Merkle root bd16988d33866ba7ba596cc5886125f791393ba6c3b689a748eff0af5a6cf84b. Recorded by Degen Protocol; on-chain publication is not available yet. See this batch and its Merkle tree

Merkle path

1. d3bcec15349c8ccafa368e131ad585d3616186c7643913072f4013f7fa185e7b
2. 517a54b564ec75b7d67d82ebdf9789d553633bcc09be6000fb5db8f7e74778aa
3. ba1f404fe5ee9a1a98604c6a4c622bbff3987c76e1859c456f240eb71f84fae4

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.