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

7f573af922457ec61df2c640eba99a044e9ba9e37fa6b81e6ea015794d214fbc

Seed

c20859555ac14905000a14a230bbf50e8cefef149834b90179450f136e069bef SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

61e157d92dd715b0ae996310f518d142

Commitment

Batch 63,170, Merkle root bb15c47590e5d97a4996957e6605a9b0fd9472d3032950ec8f62cf68bb4607d2. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 94449be88d49c262e535ccc2fe92a881f659b50ef57494508ddfa214ec99e68c
2. 04ae1256fdadace95c236f9fcbeab4bb6ee55c419661fd7df51f6c37e1204915
3. 455734bc896f004836af2f5b77a92eb465d36f338e76a6a1bbe8dc6f38001be6

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.