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

1bc12ec438dc9f87ac4ff6e19e2c88c8cfbc89500849679b85faf14da759798a

Seed

649a6c685bbb454c9de8c51c4c6448d953f88e1584918b99cf19feb119e10469 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

c33de465a0d91e63d02bbf70966e2099

Commitment

Batch 49,961, Merkle root ee1520bc3247e2a854e21fc70bf7f05dd969a026c99b073bdf0c8f04bcbccc69. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 59b6739b951fa2d45c688776522ce84eeff8b742b27598f53840e440b1aa6997
2. 48a540dc043581145d8565774ec809271f0d702e0618691be7e47151472a133d
3. 1f998cb1e6c607247f71a4a091515f3981b24216c1b837d487be2107381536b4

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.