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

0cc3818dc21aa3d3326b5b5572ca9a54d9b84f6a454d66d6ae36488241b31855

Seed

0a9c8efc47c4f4bc4b5fdb7b5bed890b54123d36256aff86ec46c527c4ecdce8 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

b1c29ac42aefb1d1b13264e15c0ad42e

Commitment

Batch 63,231, Merkle root b27c46d4b6bbe550f4c983048dd1b9d575b74d214394f3626b57653735a7dc33. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. beac687849f95a35594e7a2a32a6366ea913b3d5a5613a93539db7e328c797dd
2. b11c495730d8b87405fd55344808cb1c00f722092431ba13600e8108b6f9370e
3. 92c950bfc61be8967f9358e6aab320f1871e8012a59ed28006e32b882b0dff33

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.