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

206aa32336992533f12e2dbcbefaa7dca3bad94a7a8190b03545719e84ab3596

Seed

c56528797ccda93d463c64a0656e010bbc40ddc3f259bc14c845ba14e48c9d96 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

cf78c17f1725628aa61f8a7d9dacf384

Commitment

Batch 52,831, Merkle root 9547d7d62a6c3d64926a66c86728f0564ed95c0cefba74a9c067e7eae158ec35. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 1e757f12e43c549aad5826d4b2ecf2b43d8d22186ec1d11e82cd9425250fec67
2. 8510ea541408934b98f64142eb23a1e491b204b72b6a95e3d3c6b61a03a89705
3. dd76d76cfc7c578581c204d0fabdca300e924adcc4373aba201dc5afefcd638b

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.