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

d4574f53a7ff2b1b7abcec64e92e4899659314aaee34922c7d29bcea3fc83048

Seed

5b6f445528eb4b116e0dd7be58345afd8c523315f5bc2035a2f058373445962c SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

8089170d3b59543d922df9290cf5bcff

Commitment

Batch 49,807, Merkle root 08cf54a252003d6f17a638ec889dfdd8fc3ee38b3cef28f6881254947404a0d6. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. d888c3f7ae29f30bea124c5f8ba027f31b6b748e77d69ae76b835f5b61082910
2. 9c2f73d59fbfe075bdc7fb6beacfc7764e3596c22c7ae6aadc60e3214972d919
3. 8fe5f247cc365a1094d9c8aae7eb7bf7b216fc0231f0cb393fe2f11002bb0624

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.