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

ecd7c6feb472eebf7abac24237b569b9848bb8057bc5c3d582b4ef58db68cc39

Seed

f9e2316034a5835047ca708c1c0b3792a70839846d4782682e640ca8469eb1b0 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

e1947e7c4a290217e8304aa35cf61387

Commitment

Batch 63,455, Merkle root d24dcb57e511e0d34ad050bb3afb65d5e24aeb7261b43efc6349a52bde5b35f6. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 59e2ff61fe1ae35baaf0818677dca6109f2c25ea68310a3e084b1e6cfea7492f
2. d826cc109be81cbc158bb8ed16421b31240045e82783444f4b4e91c56c949720

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.