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

7d02959deff743f485160244252167f6c3572efed4461c968e902f04451ef78e

Seed

2299b07b4790f05cd9c12558cbddd68c4af56185f0c58945fde0442c3cd4b69d SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

e7764125313e3720821d6f392038a1d0

Commitment

Batch 49,844, Merkle root 3c95f8ab04241f7705d8eeca8d870882ac95e8d0c31ef3261cc2e69b4cdb2935. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. a8807b502ef07be6e76468383dcf6d4a093bb52ac41ef9e66adeef34385e069c
2. 6a0d93b5baaf89b51359a35115bf038bf4d670c48813213c0f20723b15637b5c

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.