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

5b625a048cc0b499c010cec2150680f2a6f1fbf5daf046bd094492bc2ea076f5

Seed

77c990eb5863f7be9d5997058e78caabb94ee363709c44800c9e7ef102d9da8c SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

115a7147882b06da567ca410009d0c75

Commitment

Batch 56,570, Merkle root b8bb4ceede911f9e4c2f92803dfebd32c821d8cc8c55718298c5683db7bd0726. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 88127c980beace3c127e04d9fba25066b53247f0ce4c4a10b57449c3b82c7bdc
2. 48e43b7fc10aaac06945fd6fad5cc0c678806ab8f5ddd8dcb212ee0d2f13b5d0
3. 5437b19f8e589544a1e089746306f69aa6432c19ad7025eaf91bc9efd991b31a

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.