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

3ea79b100c5ae9ed406cf34391c91e0757ad629715536ea43bd10d43fc659707

Seed

cef95de443530342b78eaa4d795986efe0a8fc996dcbe8a57ae171bb609a8404 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

995d1b18ab87cd9f707865762083e7d4

Commitment

Batch 47,292, Merkle root 5bd6601a4f25fa37762f61ea6c33b6ca4d81e6748125141b157ca7ec7f862ff9. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. a10df9e7c56844f10ab3fc252a7a5619366705f2637ee852a01fafb865ccc32c
2. 72bc9b2ee333d3e04118fb81723379a543a8a944bc89fc6e986f7adc1784d882

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.