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

db0b5a11e39b0743dcbdada26a51b7ee1c02bc1aa2a305db74d3d187d708bac4

Seed

05ac62c023dc073b61d8d703292c93c6bb9651c7b2361c306fa48db59c5296ba SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

efd5a9c84e03baa1485e75bdf7c290b6

Commitment

Batch 54,629, Merkle root 16c6395f3806905bd8579bcf47060ce11c1a914c1817b5e11929e6aa084b694b. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 3f1bccb71fe9bd465a0a234004818b3d32236cbc8cffd15cb6545c37e8f29358
2. de941a680080d2d54cba2a018832b4b27c43467332b73b772fa80ea9c96b9c52
3. 4ab0579df5026f390d5b71681cbe5148d7e7ca9b86283ce8973ae739d5a3e58b

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.