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

8feba019518ef565b787d17edfd45d31ca94d6bff8f0afea6a411764db2a7d9f

Seed

7b0788014d5615398b870da5ce3dfeb64d9d7827564bf095ce5467fdbf440720 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

086c4c50115104671e71386a79457bb9

Commitment

Batch 52,456, Merkle root 8a4095f09d0176d083887e3838314a1f028b45cd972bb40a15680931a13e1a45. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. f8c362675989a0d719a62a630cc00b32f3a62040e0b26331cf2c87767824e6d9
2. abeb6c8d5b995944054188ab96b451636695c0871905038d15aea6287c393e4c

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.