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

facba0d6120dfd61941de525d2c82ea8aa49634ab058295790934ab8ddab7219

Seed

9fc06f2dbc7032ac159330a4e9c2b53dbec9138e77a7e67800959d9019db555c SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

98d4ffb1ff5a1c6e0a037491248d96f4

Commitment

Batch 51,890, Merkle root c101a7dd4e29557444218270501c9aca330b00e986af281e9034ac890db21d4d. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 0aef36d3dfce9452f2b3c04464d9fc69ff18a3eac7b49198e19feebbc6edeab8
2. 07224f67eedf89623c27235ed13bb9279e238322291f2c679a0797c3ef4fa00a

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.