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

1388a2e4b85457a4fc7888a8b046c001c7fd042483664104a4cd414f38be25b4

Seed

2ab3837406f8cdd382ad9c00e1f08926ab8c258d832fb0589f0826eb0fe4d745 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

4fe655a650280b27a28b8cd722d82cca

Commitment

Batch 70,459, Merkle root 9ecfe3b627da81dd56f4832e19ab25d71318e1776af2b81e04fb97c604e77484. Recorded by Degen Protocol; on-chain publication is not available yet. See this batch and its Merkle tree

Merkle path

1. 008db2b68326b27e4b291e19e9c33790a31d868bede8074c4b335ef6c056f731
2. c603e4e44361e76e8389344e4653403ce1ec729bb093902696e0405c90f54d9e
3. 3f49034499b35dfc0db78bc1e80bd32af2f3ee4381b127ea5417a05be19d1dc8

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.