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

5165e7c6402392caf8f7ab7ce6b5919e6e9eafad9b4cd97a593cb7828112e631

Seed

9ba04266853ee3edef1ebcc2ddd40392b39a2cf91c840c89bd203013f55d33ef SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

c9e13a363eaeff465fb5374cb044fc1a

Commitment

Batch 52,169, Merkle root a0574245b8ccb4b0ed6ea7c55399150cb9103521eaebb12335e0e3666e357673. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. aaa6a356d7650d955efc48ad1f651fc6c9907376355f67cbf8c3046712ea4023
2. ae8cb8d5292cbfc9207fdc55cf8ed3d61626894319356f20eb86e2160a2b529a
3. 3369d16ab91261c7250ab091638add6dee9c4e0418714e959c1ed593a586fbef

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.