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

13c82bc3d2f9e15f84ee5ca7cc4c3a7274e6be33785b557b53e00ccbf2256c3d

Seed

7bdd60fe60c638e113af126b154d0022230a79809edaa0d9d51564fb28724f3e SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

b564f22879c6dc7a9e59111211cf8629

Commitment

Batch 57,584, Merkle root 2484e5e22928a4a2f656fb37631cfe498b25e7d1bf3f0465c9aced1586997850. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 550c84398a1b90363783c72a4aef292f33da316718cd02b8f9fa0766c29a6908
2. 5863c49d083418ba33a9b5689c2af192bcb5e2e1f590deb8cc90eafe09c73f87
3. 4a478a5caef9c7710f367345013867d8fab262b41e6cca54d00ea2832572115c

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.