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

a4b6251330f22b97d75276354dbc251a9ecc8bc5a276226c23d34fd0920a3a2b

Seed

1379980a2fc6fcb6d3abbfb237f50ee16db7d7c3955172971ecd9f7ec3bee558 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

6bbdde1976003e38cd9797f78839d224

Commitment

Batch 58,989, Merkle root ba80af200309a6bc7fc35fcdd19e315be73a9b759603d2dd1b7889a2be3a27fe. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. ac58726deb8c1a8dacefa586f2dcb738482dee3c2331e6197558ee98b4e95d6e
2. e09e8043a9e75395f84bf2459c14486d848fa46ba5a6d4debd6eee744f8425b7
3. c6f8340c3729b3901ba334b8482f438df7ee73f320ca13e43fa6d50c53fd956a

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.