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

7d5ddf66c7abf440e5ff45a2bbf8ada3d01a03d6f21ecb81736011db0c2cf715

Seed

51c86d58d78d6479cfbb83784947e11007d97631c1817671ef16e9b819b0f8d6 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

5c030362afb00a6a905fe009d20fe108

Commitment

Batch 55,482, Merkle root 406a3efccc3d9d18d0bcd2afab8ef1fd418cfb9c48f5b19845a0d91d32a4b93e. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. a784325f19620f91fa658e9763a9e24f1d9d4f62020c4c028af9581f7bdd8f9d
2. 3121b0891bde71d2ed89724df5033c26b0285005009a6f7dd057a381364a981c

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.