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

28054a68a3df52c24669cbda355b67ac7d5fa3933ca5b9c525caaefd5009d0aa

Seed

2b3e330242fadd5b5c21e3c594cb872e77a821caada721469f1fb4effb4da486 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

550d68dddf09477bce042450b1c7092c

Commitment

Batch 64,605, Merkle root f3c15056300151a6e64cb427ae1cde8f79d875ba7e53b83a19a980afec53e0f5. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. cd74f9e45193f2d5caa0ecc89cfb01b4fdec914d06c95d5f6248b1a35f5ed275
2. c2425a34e2de51659a5226a3bb974162c7fcac906db68f3edf62a0a872f93471
3. a9ff8b75badad090c2fa6dae7b18af5b9b66f6b362d1f434b2807daa1929f520

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.