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

c433da207a6ef261b4e2ab74917c148d92a972913789b7c55897c9abf26715ee

Seed

fa3d9b8752d7418c335e73513ca049c52d27fbaa553fb07a17945fc94a24304a SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

5b802e37645d0148b55b82c29542f835

Commitment

Batch 67,214, Merkle root ad6e2257c8f5d993718976fc4d902bdb5bcba7b509610ee0f41e2e4b19db01fa. Recorded by Degen Protocol; on-chain publication is not available yet. See this batch and its Merkle tree

Merkle path

1. 61dcc02a9b3029fc82c7ffa91f3876d0991ac2c1f4d11c8b4e99306d3c418bbb
2. 9a8d03b0c07f1455d4325f365c5dddcec0f560bef60d5b3fd7b135ad5ba9cef0
3. f5406971d1a32f8f271d80589722682dff0bd386beb0f803bc2f72b167adb5a3

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.