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

1ccc8c216830b88faf42bca48916a103570ced0ac0b0b93e872eccb59f410bbb

Seed

17b0d71241c8f44f0f5ed3217d4793665bab81144f552ed3ddc8a22b60a10576 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

6b4a40b60442d04fcc307b7d166dffde

Commitment

Batch 70,526, Merkle root fdca4c83c491eedf991e6f1a51aa205349b51b7bc0ab9c4d9e0555d10693c150. Recorded by Degen Protocol; on-chain publication is not available yet. See this batch and its Merkle tree

Merkle path

1. 6ca0969b40867f99ea307fb6ea126b0c3167666c9ea8763049b6482bc87ad068
2. bec40e05a6666ec0ba77eddc10162c6cbbd0c3d71e8987a346165a2b4d1356c8
3. e406ba4e6c782a503fff31fa1e1d274ec4e90cabf73434ce12e818c35e7504c1

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.