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

75e37bc3993d9cf9b797691561a7950a7aed21c7a2c1ba4089917a9f519b3d25

Seed

efcc0afa3aca20cc81599a1943737ebe3b5efdfda7af172f9b3da6e86202eb29 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

d9d0dfc7dd72cd45eb038cf7be896b79

Commitment

Batch 72,093, Merkle root 121e62d481c4c7be7e91973173fc2d27da69b5ddc86948733e9d4617f7da4433. Recorded by Degen Protocol; on-chain publication is not available yet. See this batch and its Merkle tree

Merkle path

1. 40d3a1927b5076f05cfdcbf7453cda737231ccdaee49d6a623312564032c0ef9
2. a4ff11c0d575cab44cfe1a9afa4fb3078f5bd88c61c10116a382144290a183d6

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.