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

4d434bcfa42a7e1d5306d99a0259095da78af0e1132d20e1b1feb22c5168884a

Seed

0a87486898a0eaaa4a5e73215bbbd4efa80b4cee878193b31632120829bd2228 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

c9f222b35d85871eb5f279cfcce88616

Commitment

Batch 56,107, Merkle root cbc4036ced3a914c8cb75527d2e3b307933108cfe5263be25603d123762b8f57. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 8aa397e410adf88a4d9a7b7ef52b33fba1011f651ba0b415e1f8881e42c77534
2. 0aa049b10c121e349aca8fdf90c2ce29fcd86f4fbb198ba6a054650f8085ed7f

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.