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

dff61c2cfb692047d4fad88cd0724783910786eb5fa827b734e537f9d448ecfc

Seed

877d5ca76221b3c79a61e0e9744c3d4dad675d05059d703e8f4ccb1d55b3147b SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

61edb8c29a644f5a4c7f64d457c16e33

Commitment

Batch 50,795, Merkle root 878958068ff08e9107eda348a4719607f6125a283954dbf1ac5f286c554c0f4c. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. fc9b171e99922aa5ebed85a951148ba520bd774c6d888733a180144c6ab08355
2. 695ba1af1298cf7ed118fce562e43f157baf9a0e7ac6eea303ed9b1282fc8541

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.