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

c754aa45014f3e75b2cc3026937e67f8e28b9595fac19387f355f2449fbe0ba5

Seed

f509be9ab50d8217ba1260833527c02ae8eb3887baaed1992f2bb50d167aefb7 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

e55e76792f6859f00f4d2a95342e0c38

Commitment

Batch 59,799, Merkle root d4a1f54a264cb311a955bb31564993f3ff54c0c6e5840c9e5613153611b27807. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 885c02d1ffba734a6e5ba4f9bbbf96e9aaca8b92c88a5a271cc662d3899b9580
2. a71ffa54e49199177f01907999da176d94914da0b5cb37bc70fac9cc9cf3012b

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.