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

89a978cbabbc8214be377ac676aa5b311e9dfbad04958253f2736529c07aecbf

Seed

27c0833474d39b2721df7c026c59da75a68b2f84462e7b734229e2cbcc228e6b SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

19a3f9d0077b0221e53ac18568b90c98

Commitment

Batch 62,094, Merkle root cb45fa1dc1a0f2c78510444e48ae6ec9d1cdff27163795dafd45940a95b8cd2d. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 481054d9708055ce6fae73d88cd91b72b6a7006d60d86795ce37f4aa1b77f4bf
2. 5538b14dabe83291b630b806c09b1bd53f93180bd31367890d9cee9556beabfa
3. c8f389e2a8a9f10795d2517e6e8f6ef74199c62bc424e54fb210caa6c64d9a1a

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.