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

1d816627b644ca0ea7e286550347b34f39c263c250567964da4db262de7ae88c

Seed

10f4a10b3489abcc57b564af43faff7b84918994aceef92769abdb303c4dd813 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

fcbff44fb9c8eb4817b489edb73f4e24

Commitment

Batch 55,196, Merkle root c77a543055ca48a1e30b8103e9f61837d4f13266811ba7b55abce4e091c8bd04. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 3086e29c95747c219bdd95702608a2e1997246e372e4c0bffb8c6456d120f81a
2. c133345260e9029c6e512aaf808d5ae3ea6c518f761c033caec5b4f555d52510

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.