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

02caf64824d2fe2ff0039ceed0c5bc486a50b3cb49c61ba9ad533609891b5c2f

Seed

d550e86dfecac52856f44b5c7e56f4df0259b12f521de126f653d4d720af16b1 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

a686b1b6f32ad45f23608fb3f790857c

Commitment

Batch 59,359, Merkle root 6450492c9be4a5eae336b638713d2451b349f50eef5c1b579bfceaa416fa6b1c. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. db5e17d154d28e5c87dccf23db6098e71eacf2f52f83f53c643d83edf1a661c5
2. 6a340264f75a5c0067b825d84bdd7992668b461e3e1522006ddfb0086817d9d0

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.