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

22a073ddc717c9b2571d1c6bb9c21dc05bf2409cfdc201a469905a526a19896a

Seed

633f8f428e639f37b8f5f8f6047b592d45eed983498bd9840b78a21496f1f6ce SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

8157d5a1e2646110138dcd7a89732750

Commitment

Batch 69,143, Merkle root 921b6b0e7d6625fe51bf3a733a81bc0a84b7826d7b92878e22dfef119e4b92c9. Recorded by Degen Protocol; on-chain publication is not available yet. See this batch and its Merkle tree

Merkle path

1. 223f5400cb28be3672fb40c65028e024f990ee97a549efc604cad6cc748f212f
2. ea55fa71a34c491eef1ccb1440fec842f8738842dec0ace2370cb00e0356aa0e

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.