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

47f02523e56af563d08f6241955c837d1e7e8d7440963269595ef5b5c662da1b

Seed

3405789bee868b2d8b7c094048736ee04a8f0e811a615ad446624d99819c63c1 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

61a46628f066ee63457cfd784384772d

Commitment

Batch 73,114, Merkle root ad30801b981c11717b456e3a328967c23d9050cc77024dfeac2f8d23d41578ca. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 81e770127ccc9b26c7b0eed23ec82b55aa154c583b6bd721ddb3111e8a7795eb
2. f0477e67886022bced8200778b4213213a699da7addfa66185e5923bddfffa62

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.