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

017f5cca93ca8d9e5e80455395b9277a01622c71a74db441590a6b1b9ef3246e

Seed

1a263c061eeddaffe93ec691b0337317c64e60c9c37f9eb0be501b1b1fdcf98d SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

f8756adfca5b3483bd4c71a7c90e41cc

Commitment

Batch 54,005, Merkle root eda5bf04526c0239ef0e3d4dd693ca24015072b7abe470a30c2f26872a1527e4. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 42848034c66c82ac4718f73a9149aab95f36a92f83f021ec11ec572e8bcd63cc
2. 9698146f4848baf39601250bafde4bb73787dbc29c92eb4da0811b6a3175fdbc

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.