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

cbeac7eb45cb342acdce3a4ba7c79942db40b34ce8451eda633949e37a2bdabd

Seed

22427153a0494a80d64fddb830541682d8ee1b84927350cb3b4202a684ed4dd8 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

b2df8ffa2a0486c00f5efa4fb3019602

Commitment

Batch 68,435, Merkle root 2addff40dcb6b01b879cb8e84064f4b00f2acc81ddd5efbd8788836811a6910a. Recorded by Degen Protocol; on-chain publication is not available yet. See this batch and its Merkle tree

Merkle path

1. 53a82ce4929a961353206aea647daff982ed054fa4551331def4b8f5df9f25c2
2. fb43e7fb77108c13c90b34fcf8246451823d0972251a95c271b010cafb572dfb

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.