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

dfdc2d86fafd07b8207cd934075c0c5255b4d17a44b9fbed75de6f30e1654bb7

Seed

8813545efe0bfef9450e51ca268d098b05123748a52406582e872ad91f2bb952 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

8f4880278bb401e86eaf44c5fc52322b

Commitment

Batch 58,764, Merkle root e4b8a951990b36bb09fcdf19d29a0f9503701a406c7699cd14448b408d007651. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 200e2d66d147bc16b16e419260af82cc5a8811ceac057de5b1f2490d4e508f5a
2. a1c0d1f9ed98ca782f15cce0e90355346d762351ab23c223ca6d77875372b9ea
3. 3599cecd2ad4e23e22d52e6ec6166979e4ddff6163d367593c797004210095bc

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.