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

de7edf1205b389799ba147e2a033752da4c9e91f5107655eb7d05cd180fdcbba

Seed

4aa352f284f094fa879ed6dcbe200f94575c0bb92cc55c630e69cd533207d878 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

8740837328af917c70de1dd3aedb9991

Commitment

Batch 71,763, Merkle root 2cd2b94d17f72eaee3e657511ae1b8fbefa3968fc73c4ec13a69815e3eb18525. Recorded by Degen Protocol; on-chain publication is not available yet. See this batch and its Merkle tree

Merkle path

1. 4971f501bd11f2ab527b5af91ec793ff9cf75acc2bbfa230e267d3ef850bc2f5
2. 6b8e841f9f0fa235f7087886dfe48e2c6a377fa2f3297c20f6d91c3305863fc1

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.