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

d8d18438d86a7d8a93b7bec9a9c8d19be5fe2e0505c6c8d40fa1a32ac9fb6027

Seed

9f2ef3ca7b063277f89dad1514816cfc038b06b2eb3652e331fe825564c73ebe SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

6b81b5643a9033842a8249b3e2aac5ad

Commitment

Batch 62,325, Merkle root f518608cfd61b56f1e93db0d015bf52684a3ef3a9d14346e13f138e206abbab7. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 64b29ff65c4e1f2d6ab3531bd84e35e8d6c77148604e6ddd55dc08d7448dc5ab
2. 25c5a14d61e8523ad8525540820da71607084a1df6016d6c8408468578d0ecfe
3. 65923024d7a1328d3275a4196338fced2235089013c5ba8154221d447e385f64

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.