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

d910368871d5ce9486601326c1b81bb70b86da49eecd6aaae5b695c90e47097e

Seed

f5c0547d21e6c87dc0199d98843fa08728790695a228e77a59da6e989868ef30 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

0417df52f4fa256d91a0901498e40b44

Commitment

Batch 54,123, Merkle root e93b720fa2ebb073e6edfb05dbff8198bf31c767dacab367fd5ea2cf70bd26c2. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. d4257c5e12214916b187d7d72ba5741cd83fbf3ce02a89370b24de054ba41e00
2. f1f7da4fb63f67be1e66cf8d61901dac6eebc1a2550705f5af3a0f4581d814b1
3. 03b1d842309512437a056f57735c04e5b3c34113c6fc450de5cb89ebe6eeb032

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.