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

d789823b1963a906bca34dbb2cd3acd982a01aaf1a838b43287f1556bbc1b86c

Seed

231fbb4d26e994b5ec2a47fccf7fc7c3b6ca6016e1dbd07ac786862df435511e SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

c2197402d683e309fb1c394fd99064d7

Commitment

Batch 63,050, Merkle root cdf76e6f42638a9a52f3bba6e8d4ae850d1d5e87b67e9cda5a87f122a47531d9. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. dd30e672a81b211ecf09cc13090778bdcc776f168ca774ae2158c3b1c28ddb6f
2. f4524f90e2af30894b90bd351f46a2a55694917fbc276d22d8233a2f7d7db388
3. 785b5f64f85afd4fdb7b89e5604cc5e2d12a6ca708c22a28056d7bddd0094a91

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.