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

852539f098083703a8ebf869af6fbfae7b3060c724bd5101c3d7d87027fd3c3d

Seed

88a0849456bf5e31aed0d7a0e10d5417af4ec4c8791014eb5e48dcbf564683e8 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

f3c3cf02f24a462e1184372ece3e4116

Commitment

Batch 72,695, Merkle root 32734e94eb33ec26a2f5b85e1d8949db9a402c34491f0e6c857100a64a64ed52. Recorded by Degen Protocol; on-chain publication is not available yet. See this batch and its Merkle tree

Merkle path

1. f371808c26d13cd1ccd3697373bc55ec3a833a2b81029330f8546b258db2ceec
2. 6dcd851e2d239286331e52672dc2426922f6dad2bc3c35a21c4d3bd8966073cd

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.