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

b04ee5ef5fb10ea901a0669233fdb159b02363a3c19430417406f5b2b0e8d903

Seed

ec9604b21e63b7488933bc2cb36bfeb377d4f1ac12cba707fedda02acb1863c8 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

4976d1a52ffb12819acf82b9222d7799

Commitment

Batch 60,835, Merkle root cdb4958720484d874f7f86f8cc98e11b4d2b40ed0d2211ac37231387d8296efc. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 32cc0edcfca121f070d8ca88726f72816da31345f7eef04bc196c5591dd985f3
2. d2046e844f41645dbec6e713438f057d256a80a68a394254019d8710c1ca6e52

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.