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

89d5e22b5949816d53304857d97a952efe7bb3384c1ece79a47c7598932797cb

Seed

eab90f8b75551390c978d05749c76eb81bba8bd8de33df88025397728ee3de7b SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

b1a4ec53bd6fdf837c649d54c0331cc2

Commitment

Batch 68,822, Merkle root 3b29ec95e6ecdd47342ac7f43745b574c3b1aa3bfb28e3a4de0a15a90365320b. Recorded by Degen Protocol; on-chain publication is not available yet. See this batch and its Merkle tree

Merkle path

1. f12b1cc74848754390599de4b130053b584efd0ace5f127660cf84bc225d6e43
2. 41a865065503384ba049c4fc54071d293c2e27dc87d946dc4acdd63f16ba759c
3. d63810f50de567ce94ab7a2f07b6a5a22c199ff913d76b1d4d9337650fc81aa3

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.