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

969588e5977b95fba39dd223056d37dec3b76ce8dbd3a733776d19c7050c32bd

Seed

60d5aa90119ca77b16eeb68f8cb1b0ca503b7e2a36ee678e60d63afef8bd01e3 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

04b708bac894397b140f4931d80656a4

Commitment

Batch 63,950, Merkle root 833781453501516c7ec5145ccc769961f82ab31daa452ae9e4fe91538e598ea2. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. efc577bd9e6237ae66e64196622c12c997ad1165fee17bf722d4668e6ec9a9ca
2. 6896e2bbdace6dedb845786c33decc459e6fae2962ac73611f2dd710b1c19b2e
3. 4f993db347f6b762f9020e35b01347338c189389a9152c6ec70cc8b8f9c2e304

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.