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

059f43d7b26d24f22121b512ff3c225da93a83c3a7bdf9017596e4738f44f520

Seed

7db62f11c29cef4ba102b05d7754d400b4de9f32f4b6b2d92f0b919d36bb80eb SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

48394357c72013e74f7560f93a6ff201

Commitment

Batch 51,047, Merkle root 98a749dcc7eb20356c34ac4fab33632b7ee67f5f7941af06af1157c2bf45ce92. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. a60176c2e566dafed2fbb4d68b29335aa09cc73742adba438381f060df3719dc
2. 5f2603bd059901fb3eae6e64d2c09cd5f9f68f6c5c4b1fe1bcc48fad71079dfe
3. e260539f5456a422d57002c387d52b40316a581ce43ced14f562e767cc1a7e2a

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.