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

fb9eed83cde341eeeeffbb98a644e742868b7144add154ce27bd11df65ab9132

Seed

cf9091e28c8df440351bfd72bc48cc2e857cda72ddeb6a541e423fae6b0574e5 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

f660dc10888f6f4d6a2ba27aa30ce700

Commitment

Batch 59,473, Merkle root bc22eb958c9e7fad21cec55b614bcfa96c5d3e70b38140afdb241b2a911f3316. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. c957880924a444f23a71a76c5d7ac3111a788b143655422bbe654a1f4d274d83
2. 2e329ed3646f659f7a1f22e91fa39cfaecde7104496a6e1bfd598e126b578f7c
3. 6f5e1506051fb8fac2022026766bd9ff9d8c5bc3265ff13a9518d7c6d1a00b9f

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.