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

48e4e61a3217fd9c30bd49a53f470bb8c082d77b98f4a6f955dcdc076ad563e7

Seed

31d4890e6c39cd759e94580c787fd17417ada6bdd5c3f30fa899961e3759839e SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

662d91999e043b8430440e211b3830c4

Commitment

Batch 52,984, Merkle root afb3512bf163de1afbd4b1ed6962b0ac25a8ef80630a0cdbc37b74fcd63ce77e. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. c8369d0d216c2cebe908efa9bdb7552332c01c791ec9d90d7b5315977d29d629
2. cff09701d17c028650db38d036db681703f71c0b10eadf91be21a0c0d25e8848

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.