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

7b224bb8dfcd91b28b7e2acaf006e369fdc8253111a3530890dd4f626411006d

Seed

220406f9e7e22cc54efa3e6cc9d5b8417b5f390dc54c310b3faa2af4ae746ce7 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

2bd6872bda820aa060a039a8f0e284a2

Commitment

Batch 54,941, Merkle root e62831b829577031d5c02129207677274e85f1e3f0d4949cbe791578d3daf7ef. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. d97bcccad474e1dc8503fdf3fe715f23ba41d0572939e67578d3dd1548fd82f5
2. 69827ad021ea0fb8ab9b11f4d9be9be470eb1b95799671f2f8c580845a6e8323
3. ca8ce963612b40cb7412de6aced45531f4c204b58a63ae8ba0d39a4e5cb441f8

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.