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

2c7249f3c57ef0c8efeff1879c09b3d628d8f4c9881e8fd7f3d232d77403312a

Seed

7e4e3b20d7827a366ce64858af2158225aab9eef55d4cac449c9b669f5314e6f SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

2fab6f6fd4d406524fdd5453070d00fe

Commitment

Batch 51,516, Merkle root 2aeeced88b53e91f7fc530d87374f58259cc845bc3475c63a9fe9b1b29b2574e. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 0dd157d357472d2abb4a3b13eea158e1f3092154aaf84597f28723e94a3eb2e1
2. 5fe31d7fa974c9cbf4bf4575b461ff1bdb7fa52130d9ba7450d384f0bb863a0d

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.