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

71acd4f80efd0c7daeb0c0fcbd1732c06fed8783274d5ee5a97bf1886617b3b1

Seed

12e27259b5d1e49348e1df01290afba38ee3667625bd40d3f2eaa26b5754a978 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

faefd583b4bdebce635e9236b1946702

Commitment

Batch 51,751, Merkle root d6af267e452aaa479744782c290ce8a4492e7cfe17e95d2f1757854050ab41d5. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 64a898ea2b8e36fb84e947616eb4c9490d79186a5f534e4390546c66b6f2e55b
2. bbc03b5addf35435feac306722503d65357f5a1f0728589cc70c792e081ca0cf
3. 4a6ed0bf7d667e9fcf51706e29a91d70706da23c991bb064da5cb88c2524fd2d

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.