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

77efd48e588e23b57ef1f70ff8621703b8ecb0ba77ae5fcbc1a77288d13571b3

Seed

78e7259eecbceef8e6c0a1867268d4e45ad7935cdf4ac42a896e5cd55542bc0f SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

b0ebbc58c5b6b7130f891dd29f38c7b7

Commitment

Batch 52,220, Merkle root c965527eeee3c762a1884bf70e692eaec5a6b3b43174c9b1b2bf83145ba88550. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 21cda0fdeb3db0b9d467da83f727ebde0416b98b996b1efa85170b8d2f6afd5b
2. bfccf65700dd4e0d9c1a97f910750c84a8a7acab233bd92a6807094610773c1b

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.