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

baa1c4f6a6afbcb1a360be265e3a6e4dfe09c172a7822518d3b039c5243f713e

Seed

d753af02a6a1826b9d0696243eb9192f00de470742b197e464e2c80634573021 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

d89ce457a154ee0de1fc9b401c22b9e2

Commitment

Batch 56,917, Merkle root 6f2fadfcd42187d21e16d3078e44361eae507bb32dd3078bff5daf606bd8ad4f. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. a6bfb50b074626968c5f0ec6c8d7fdf339821d0421fde324ec40e34b8ea30280
2. b9458451d8c59132ece30323b19444b34460c9ef64e3f00ebe9e504b3c6e7a62
3. 7b31ea2f5264799ed562474cacbc8af55571b1ca535a9acc4ede4558d05a1a49

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.