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

72276f322fb7360dfacefa5618c5db9e68bb3de50eaa5e5983134039e7e32967

Seed

18959c502a1e4f73eccb6251df69343ba488dce1cc53277b1d81e97c556f648c SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

efe7e293d74cc376e2ced1225132ffdc

Commitment

Batch 56,121, Merkle root 51313b30e70f8f846d74314437cf9f9fd087131f4e00f8777e6b0efdd41dff8f. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 8467c5826cd4da752470f562f42af51ededd2fe25f60a665fb8c627bb2eb0ac7
2. af08f78d9073b8371c5bd1fcd1b75d26caf022a3931feb9bb6e05ef43bd8ead6
3. 0fcbff64c17170a3c8896779afaf7fa5463096f2878a6820da72d541f95cb907

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.