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

86e39e55443322a1612039218e3e6e4ca81ca3f8d6f5aedcefe5d88080b0f281

Seed

bd27b9465429d0fbb5806561c4d9b53ef10fc913e66310dae6d332d06c1c27f1 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

ea30cf1513c74075ad68b864c27635ed

Commitment

Batch 67,554, Merkle root 85f3c30550f1274313d64e53593c14818650f371dd28a276f186a46e417e80eb. Recorded by Degen Protocol; on-chain publication is not available yet. See this batch and its Merkle tree

Merkle path

1. d750c2e6571c42cf5afc555ae4f4511f2ca75e4e401756108195e719d0cb18a1
2. 98e518b33e5dcd0942fb685b2f2d804e1cf5e008d12ab88a69cc96003e6a8126

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.