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

779ba5e8f3ae7893593db1839e6ce2525e6fa705b181e441a508a1a6c46a1a42

Seed

b7095e95c2384144714aeb39d97654475070659f811dcd2aaabebfe00f3a606e SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

c6a029b9701675f5867803c211301476

Commitment

Batch 64,553, Merkle root 11321cae5ba6d49016127f0221a0e5f0f625c0ada1c52599f462f3167b968534. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 11c986f3ad1a9aa3c5fe8df1213d00aa5855ae2a18bc43b9a4afda3529872625
2. dbbd74433eca47138c385e8d06404d8ac58eb5c5e8a1d370c729465e8d8b1042
3. 85d5af99a587597826e2a24e527e98a805d07361ed15d9a53973cdbe9befd405

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.