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

a7cfe2c5b6a564018885ede8b638086d6d020d77b91e0c113bb8905a71375ea2

Seed

74f06eb5c0acc17d8c698bf977cdc226451cafbc50866d381ae2248351096fee SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

c8892403f73dd4fae3f388a954864b2c

Commitment

Batch 62,769, Merkle root ad9b0d945f0f38bd3761acdf624fc7e7577816a9a83321eb74b8e2b0729003d4. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 461225cdee91ce5526b9090becf31a859723f9b774cd76b8430ff6da1f074035
2. 79d844ca056d6565fb085924e63f2cb5a65115aafbb46e633a906ab822175e00
3. f60c51762385d98c5c799d7cd5fa394807d6dd67645a20572f8e0abfe36492f7

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.