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

583ecebf82498dedb33a9c5ad00b827170a3ddee6892bad5d507c110cef3eed5

Seed

da25d35fa5ce2431a0e17d9ba1f9b658c2dabffadfba2b9fa6dc5790f26bb51c SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

bd43ef54a19da1eddd2be4618ef30f08

Commitment

Batch 57,370, Merkle root 6c836ff0b7cea505d1b8e8f168be3fb52bee8962962252f0935b97a867a5b2ba. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. dcc85ff5890211e7b76174099932c1da6c953609bcffae7042379d06823e960b
2. 0b7c1ff205ecd5b46c2a68f019d6f75e20e571fa1e5daf1553502e23b64c83f4
3. 7787c156bf1af2654960b2a4c6c270f35b6b57e5b4bb2fdf99c65b1af9f0a273

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.