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

5482c6d1e6b2e75fefb6238b5fc067a884af71ace6898e5a74c25780744af012

Seed

9a30d98d4d547c1c0739f7a3a2963168edba5c60d90184d4c6ad6f6c93043b77 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

dbd67065a3cdcd8016c879d33b708b29

Commitment

Batch 69,340, Merkle root f569a6fcecefe7f41cebfb4d9323edce90b16bebe496d86657cbc7524a3dc03a. Recorded by Degen Protocol; on-chain publication is not available yet. See this batch and its Merkle tree

Merkle path

1. c28fc885d104683baac00d9c946f22e745073c7099869eade31ce862b391b3e5
2. 3ba766a4627d3ad4d8c1a6f8dde9314541517f5e83b8411a621d4589057fa16a
3. bb2bfa5b18cb0f44b012e544aa7247c39f0427ccbf5f556b35931b749ea6c78c

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.