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

1ecb2182278ee36f01e946608f0ad6ce3f92c6644ef865806f5edae0171efe86

Seed

b3c9a2eacd5e32fa4993a709770537eb3b41290c3d55265a2ea8e6527438400a SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

dad086f2eee3e78724419f9b7d7b58a1

Commitment

Batch 57,396, Merkle root e299d44c271119917f462a3e904b651be11ef5cef1bcd3834de30ef7dbeeec1f. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 3dd6807a87a0a2535a6cfc220dc389a3e5f5e4c22cce50bc286979e466c103ba
2. ec89af7591282bbe99cf6559394a8fc52d8c287e038ab678db1355216753ca62

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.