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

de123c010dbc073bd553301fa233fefb6e7a2f3d9d476c92a23821f6010eb85d

Seed

e252f7bdddab1b538063a5181b18d8668ecbaeb78fc5333b18060ab34090fd0b SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

18a475cf691e5c702b7a1afb12dcc173

Commitment

Batch 59,920, Merkle root ba411b2861a2fe7bbdc483f431ad1e446fb6ff856bd2fe162a7558029acdc0f7. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. ca1c0c9d8af8634e7de310815e6d628c05b7931568dca71c320ffd762a4df66c
2. 246dee19d74fdb2d1391d6c149b057b8497dce683e1b11ab7950d8c9475673dd

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.