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

415ed70312e902300f7c0134808364b488f553d323b8982923a3311b718dc32d

Seed

e39a2d6f8ce7c844562f04ddbf255b1b3a3976aceab9a312c5901900a468df3e SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

ad67cd927874312ad1b4eb78c8d5b0ec

Commitment

Batch 54,243, Merkle root 23637286e3b6469eb765d5cf2a71bf95148950af1abcfecf7b09c9f03d678b45. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. d3250eca8090adf355a4bb6a6d5fe5cbf0b608f23cd07e1692c3eddc2a70edf0
2. 05428308ad0788a4981c22c25e937be7824648372f0a940dc50ce3d6f302f524

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.