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

76daea7a7c689d0e7c84e1cbdec0bd579a112381ef949ad070db77f3aa16a3a7

Seed

dcbafa6f348a7e4433ecaaadd9e018b6f3d67e3768b0e5ee9dd0f115e2761b9f SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

b946fa06dcdd8fb16cab8608f7d33a5c

Commitment

Batch 52,677, Merkle root 9ecc89896efda3b7ccd5dd1c32460286bc1b8623a2978e99b36728d6e28b56ce. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 8709ce7338a159d75346e9336bf74ce7f06b9d5ddcf8c527685b3031d2a11bd4
2. b18517a291807b2e42d517d1f097c032a149a2970814f0fcecc2cd8016ad241c

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.