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

ce198078dd0b9103bd22f565957bce5685de29c0ea6307ec061928f1c20ffe12

Seed

c14d6ffc997b6a244b727d0efc2ee1f357e1d11438cf53e8f0c492157076304b SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

cc1b5e0246eb15b1a82e530df9b96cc9

Commitment

Batch 63,289, Merkle root c05f2bbc34abbfb904c2acf38b8a824ca82d5c5c753385252fcf76b50b7726da. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 2134426c37d70ddfb56f2c20da448f9a46586dcc15e07cdd9aa03c7f9de2fa5c
2. cd903bf5f1c32f704f72fb721851a8acfebe3a8a5f6179283918ecefe2001579
3. 70f6fb08097f7830716a7adcf7edf1eb268e8165fdffa5d90d8115a8f4dff2da

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.