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

56e0a8d7405e586f0d19f33adff8d7acc020f93662d78b94dd19f39e0463c4d3

Seed

2063ebb2d23ad9073854cea887b35533cd8575a66e8dbb46782ddf8626bdfdcf SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

6a600f5b67330694c9859c0aa21124d2

Commitment

Batch 50,743, Merkle root 59074b700f05e329c6c3db6e5875836636cc4ab915c2d36b0549d39bdf0de67a. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 3bdfd2b6506d6d9abae00e5b94de02569fe7738fcf8868fea97cce30ae950c4e
2. 089c2b4b7150177d8c8a7fa9e5c673cf4d235aae7819f15a17f253b36f2d01f3

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.