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

aedf0ce896859adf6e9920c4aecf39a783cc9e830080c825bc6cb6792870c838

Seed

d17fbef98ec7052f2bf70adb724f259849badde91cdd705cba4e598ec8fb91a0 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

2b8b092602294fc24acfeaf1450fa4c5

Commitment

Batch 51,018, Merkle root dec98f670ed74a2b16a9c991094b270376627089d1663e236ae22dcc8272a5d6. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 54ce6e25c911066ae7010c9aed4b78d914c94786eae87f7ffb1fc72ac7260bbc
2. a5773370a38d22ade3d99b51ad8877552165fb86268115383b04087100b3843f
3. e697678f9f4545691b9a43c07f66eff9959aa700f7f380639da383c7dd5a4db4

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.