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

9bdab592976cb3bfb8c99d64d7d96c214d2f1d6d2ebce16c87375c259df55679

Seed

c6984754f6e1c2fa84a371a104eaf554e68af8dc5bb58b28ff32ec39b55b107d SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

d83443b4b6fa6884509501113a1cce0d

Commitment

Batch 58,203, Merkle root c17fa55d1c8019b6f0c79182e082258570a08dbc4ea1d1cc4030ab2e3c2d1964. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 977e12739134a2e41605d1f04810ba9bf3562ad4661be68a4c3b7ad86145a90e
2. 42e7e42be8b65ed46a2ae3105ccedc90997c8920984992f306fd6df1dd04a8ee
3. b16601715d2a1fa5fc31c82f223ae7c64a20e05eaa88d2979e136905bb4533b7

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.