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

0b95fbd261bacb2dbbaefed27f60c90083c0497078da64b7ecf3ba4cd4af31a8

Seed

3f65c27954975de4f21e5863d01642da29a502af8b71cad63dcee90bca3e503b SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

629ce8f27b03fedd8db54bc5d3587a31

Commitment

Batch 54,779, Merkle root 3fca3ca50a1a05a1717cf2d0fc32f4fd319aba90b109ca4b1d91ed0875744ece. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. ee4fb585a41e95f4ce2568a66a0ea5fab4d0192471172747fb2b60fc186a64d8
2. 9c45110e0621b28483b340cef11f64ddbc25491c76bcb78addaf44da4889a283
3. e568aeeea419b89a09a234bd0e3e89ee70400f67308dadcefec3f04fdc303916

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.