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

6cc3bdccaf6df7081f0df09ed567242a4a8eb9ad04117eebb96fceb4bc4c0d39

Seed

0ad0da9858a7eae9a8d03336e086aa7f4d9c4c3d25261e607f9e09ea0ca78ecb SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

c3343ab9a884e02d53b4789f97bf0a3f

Commitment

Batch 48,562, Merkle root b87d694618914be67786b7584312f497e8c3afdcca94a97e3c76010c2dce3ca9. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. c99d34f296503ec7d3924219d514f43f95a7ac9c690651cd897d4baff18b15af
2. 107fea261b3082499a8a676ae4ea2853655563bf539142f2b1bf455cbdcdc8ac
3. 4686fdc094c310804503eaac635e311528bcf413a1860ad0361692b1f8af23cd

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.