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

c01d4a7f6b552d68f761466b419eb69f6f94f9c5c9dcfcd87ab7818a04be7d14

Seed

cfed390c6e4dd512e4a51c2f6a585dd8e51de086d9e4620e36b67157e6a945db SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

fdbf50fec30fea1a61b425acc560042d

Commitment

Batch 54,897, Merkle root 0320ba2981b0cfc525463bf780e5745982a4accb32272658608c89ac90b88c3b. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. a3be156c9963d165b23ffcc12edad12f1395d58398292793f2f803a70620f6b6
2. 8ce558ea1e42bc509d8c6174e79ebe5394558920fa5203829c8c737e409d4a48

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.