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

bfd79d65f92d270869d0ea62cea17ebde02dabe862f60912e98109c839bfc2e8

Seed

ad95682ce1d1139e8bf5a7452b8a3701a3d5f00f5c52346efedfab924cca5582 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

c0e8344aea0726249ae997c1222f69ae

Commitment

Batch 62,437, Merkle root 98c34dc8e793e930698b79b9dab75cbca01cc7415dc3cc89835b03df51d67ff6. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. a5862cd0a9f2c89869934698e5f592f1739e99ad42bdeb16c0c32a37568ffc6d
2. e2b94f3a3e5f524f9a020e7d7b3d52cecf612c5fce4476a17ec9f2cb67dcf01e

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.