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

2bdd19f416df2989f4605f810dba6845d8b1de3753f498a388f12133ea3379cd

Seed

8e0873415992a83d982ee8daa069570a3f599e32bb718a6cdad1811401d956e0 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

16e8f295fb6b709feabdc9b6448a130b

Commitment

Batch 71,533, Merkle root df572b0cb5fd50a296e705cb76c5122f1dd7d7426e5b30d04b31e723545ad810. Recorded by Degen Protocol; on-chain publication is not available yet. See this batch and its Merkle tree

Merkle path

1. 46d52534548f39f20b16167a69db3f0c9493b1bd7e9ceb526cf6436948e67d9a
2. ff9bbb2223675a2b922e3aca1486ad513b55dfe506e4224ba19cfd6f8c47defb

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.