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

816b05b5e25d2ff43301d80c94c1412d4ed47383be2a6e6b85578ac03f1bbc0a

Seed

7257999362ea59744c2191ec42a9dc5ba898c396c9b166908d26d16970a5e868 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

57c140e94408af76a5e3f4c33ea04f61

Commitment

Batch 66,681, Merkle root 9754413baafbf14bdfd6a1d71a2f79a8a5a4cd0df4ed0eaf31cda60451bfea13. Recorded by Degen Protocol; on-chain publication is not available yet. See this batch and its Merkle tree

Merkle path

1. b3f11df65d49a69d84222b985310a004729ca8be512518249eaedc2e61e412fb
2. 19f61657e543fc77a627b9cc10feb6cc099c3fd4364d14372dd71ac11e0bdcc2

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.