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

005c312b9c97e0072a16f5ad2701b14e1019b863d7b4b33b17f01429b2a1160c

Seed

a4a6de0127841395072502d8d73371df553c715b9d362c30afe8d3abd1fd46be SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

3fb02d9a1468f5814374b170c305795a

Commitment

Batch 50,077, Merkle root 5bb78bba4012667553a3ef0b8aca16dd61df3605a0078946742ae2011dd91ea3. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 514fddfe55ae47bcf45b2783eff11151608f47d067b33fe08b9a959bf02137b5
2. 6ba48863b9576a2ecddaeae5e0d5665cb036e7df7bf9b454e50941b0be55813a
3. b3253c6482c093bc2f4374e846da911407af02270617fd6b3dbd46a6cf65132d

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.