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

95fbc7b88871759fa0b782e5d9b25ad28b533c8eb91c010f0139887e19ea70b3

Seed

c4291173020012232ab7e177056736bef716a2b1125a75521e4327a4d13ac97d SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

0c8250cbca73fccc64cdb82d3690b4d7

Commitment

Batch 56,762, Merkle root f35a75f8861fb60b703820c89d386f36bfc8a149bb9bb9c830daa912824d7184. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 63790f8c732b9661201d1f9de29d7742a1f83c6de9b2f1a86e2d086409308834
2. 8e2f6e9a5459d68935c6a9463125023c3860945c167be52fb9d34c8f88c223a1
3. 2716336b036bdcd0301a4de5db03ee4af72a3d2aa3334a1dcde79c58f01ce377

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.