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

927285bcbf7024a1771a36df12ebadbfd109fcce98a18f525579e67a042cbb0f

Seed

e89bcb1ada4a19544a1d7e8e64d7e1ccc41a8776433e5dc30b36e32bf5958449 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

b6ad9726d99d417954007b86f13f87b5

Commitment

Batch 60,157, Merkle root 4a8be1303017e23d1fb9fbbe69e11ab4d7116510c9aa9891261a4559fac1d29c. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 3aa00e730e84a035981d68c318cb3c6f6b78b093c01815c536fc1d62ff2cd248
2. 8a93ca18a7c09786b15c7e92dd4859b074ffa6a28f0a9811406ac8e4f4ddcbb7
3. 685ad83d66683079cb38cea8977c617ccd1875285ed8901f185bff17d93d9882

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.