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

132877167dfc28b0c1f16a7231f1804c95d71fd036efe993d6d9cf38013c7a78

Seed

91c9281497eaa6adefa4b18d56bc802616ee05d33fe8eaeacd1532613491decb SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

55ff179360f1a658264cb8551e374d33

Commitment

Batch 63,003, Merkle root 4a5d7a722c6c823c83cf03e3731a04eb0c8f2f9c9a8722a8b8c9d8409780d687. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 3a3ef5d97402188ece16d6d5517598a9aaba04b7e6b015f92700af50645783f3
2. e9ed50662e82fa1b5fe2e6a35c9cb2ba6209c90f0d4aaf94a58f3336ee00327e
3. aaa0262c19835a29af69acc3e83be85983d8c08a940b906042914e8fff08b6a6

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.