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

22eefbd5939a076eab6ca2c5b57c7ae8a9286ad31243b29148600701a21ff718

Seed

3f0d603c95bf214497a9b0f1596ac4cb1e62cca86f449c83c193905418966ea9 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

9a4131b55c104a7a750f93ec124b4be5

Commitment

Batch 53,305, Merkle root f02a87a02c152711131ff665918b3ff2c20a9333c767af53c6f13884d56b9d4e. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 949a19da5c8b3d72d3a23b2505932c2d989609906e1eb18d8a9131a5d550df86
2. 175df14e7c8fcc2a6d65f9e05d4e97c505211d5f5530ccee86483811996684f3

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.