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

6e4d0692aaa469d2e406896ff0a88f69f91009173961156c6502c2f6130771b8

Seed

2182127bd67f76d5a9900e292e46589428b987dcea2ef71764ed3b005efd1a47 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

735d70d083de43a7c2b77393c30093b4

Commitment

Batch 53,773, Merkle root da583075c18929135bef6997a8467107395bd4b2936994dbafabf6a6e78713f2. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 3a7bd478a06e0569b78fe7f7c1ca0684d1ae6cc2ad3913dfb4677571f73d0aaf
2. c558d1cb1e2f8d8d89ce6b3b47d9d78065e63dfd8f5b2509d368d014c1f36784

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.