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

8d54c368896cf252ffe7b199866594ccbccdad732ce6961011ef8da5c3f6ff0a

Seed

707ff23bb4c992585314a9f3e823347a28c1def6c272d7e8a7b8c2eff815332c SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

ce58c308c438487bc39374ed49a16425

Commitment

Batch 72,787, Merkle root 3639cdf9ae21042ca8c954b5442c28788ee57b59410d8be30d220eb399c82147. Recorded by Degen Protocol; on-chain publication is not available yet. See this batch and its Merkle tree

Merkle path

1. 8a54e7f535a520a212647ac5a51a6f79b22db6c480f9d736e4e6ee5d4ee3ca78
2. c819c3c402daca16e90ea7bc68a8a2ebbb32365489f23e202f8d559a495f5bb0
3. 91c01b9462f1039c189cdae2bb81834eedac1088c868334e78f95aa1b0790540

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.