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

ad03f410b1a34d8753c1d4e00a9b128382d4b4ddb149cde6a625d7e7ee105308

Seed

6fed663521ec658ead8312e8cf3a135e2ad4e1743d59beee974a703c265ab267 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

97e5761994fad6e6cad0008d006af201

Commitment

Batch 47,750, Merkle root bdc44c1d8151fe74005c0f9ea60203c29338288cc279af80392918d5c34384dc. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 5fd5de72a52f66ed8a850d3d6d9ed424a79fcfa3695a0a583cc3df8a5f8464f4
2. 2693080a39e5f73047698e4a5135efd3dd275d736064f0d048255b1711f963f9
3. fca496aaf263bb3e06bd83b0bd5b847d0eb3eb7b17a694df07a2cbd0b0d8959f

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.