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

20d077db5f8667e44df94761e536996237702df3227fe0c988a4eee618e20b04

Seed

eb86cca70776c938ec25c4d16014c44c5ebad088b618f158c775db2b25472dde SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

b7dd925bfab0413b88da7a9d1d9ad8f2

Commitment

Batch 63,886, Merkle root 87bf72788249f4182927ecd2c26b89bc468798d5b6e531a5ab88fbead45beb37. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 56f9e00c7c5f896475284c5905e801878133f2df6caf1fda82d7259b00c7251e
2. 509f06acbe7fde6e75382baa89287bfe77b520d4559b277ad1626ad531f8fe7d
3. a1babd6399f16f7bb8437c012dd0f5e5e021c0bb6d11941038ade0c1ba745970

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.