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

a4e3ecb80d470934ce6cd19d38b0f7084c9eff584a22af0381f0d2da9bda63c9

Seed

f2e21f1c13675c5b05451bf2a17e9d9eb427867e10cee049095d1b15b16f5f3a SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

1b4e1030211ce49878a0516ce0491c53

Commitment

Batch 69,440, Merkle root 0ef6adce45aa502e2c04b2c0ea020a3e497b2ddefec69211dbc81863ed6f98bb. Recorded by Degen Protocol; on-chain publication is not available yet. See this batch and its Merkle tree

Merkle path

1. 5c345ef6ebbd73d63f2d928650279c30dbbf8def73f5e28f336f0f1479a5d787
2. b76fb4cfde910fb3a82558d49b6860dcd6a6d7038b56fa86ae70959afaeac9c8

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.