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

382d1b8b86d899ae454a8e5c2baef90f7d703baf69d2c73a9f29ed0d9b701b07

Seed

a37da5f537f71d269b71d3354bd725fa1ac1b3e8bd9ca7c2c53ebab038f36d6e SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

fb7df58602cdef6ca1de2af3df366c4d

Commitment

Batch 49,104, Merkle root 5d16942f693477ecb82d634c34ee23e0b98bacb41aa1198708c9eddc1711414b. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 8f5731f91671e063a0291fb1d8baa2ddeb60540a629d4e2e752b6764777f8474
2. 55c20206d6f4ab6c90addf9823e31fcd2bae16ac682dc93d2acd26c90007d16c
3. 628791d9234148e915321b3647b63852794a5739642c5cec041a8eb1a63eb91b

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.