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

e418647bfe8903009d58a6a5176ebcd58972bb86428b9edf8fab2a260ad53739

Seed

6e8da3d5840f4d18dbd838c8fa8307eb9d24acdf7a656902e55a64e2a36a621e SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

84812f4021c114cb48dce02fabc4f281

Commitment

Batch 70,262, Merkle root 31790d13f7321180f28fe528b6a3d3a932937430e0357230480dea5c94d12c08. Recorded by Degen Protocol; on-chain publication is not available yet. See this batch and its Merkle tree

Merkle path

1. b62d07677bc5dfe7c27677eff7c7366c22fc66a4418178f90bd16c304cced163
2. 46507de9705fbe94892eb5fbc005f8e4352fb7eee1fe35ea56eec4443bce2dbd

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.