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

1f50aab28375b8e918a1120b6f4a9781980e3d9afab13e0e026a6e0b34d3b1d3

Seed

1e16e2fccfebc2aee2c93db8fdd5c9a651ee237a558485af500539f01900dafb SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

30dcc8eaf07d8a210b21e5d172838737

Commitment

Batch 52,746, Merkle root 520041de6c6c79eed81ef393230610553c4c7e035a6752230a4dddf7e96aa04c. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. aa836aab25a9a25a5c47f3a2d61999e34af2dd8fe888e1d47d9d2d8bd66a7dac
2. 7f2b0ad81d52e82724f5c563bb97dde44f79783cd61cb72822d4604477a67370

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.