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

8cbc292cfb8c4974b0b5e74f4e5f12d8149c83fc0a2b24871c49edadc5a033f3

Seed

2a3475dc7568d81669f9a97397c7344876c6c4b6854789e02c10ef01531cfa42 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

673c8e5e759d94725aa0b15cae95aeba

Commitment

Batch 64,323, Merkle root e24056045827d4041524a4891bb484dd6f3cc28e42b5f87011e70c48ed522f55. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. a3dcc292f3596ac256bf6f2e1084481de7fab6e77518b8d98c0b39b1c8abbe7d
2. a6f98ba588fbdd5f6d4b7d97c00f7585224fb0cd21c832705f7d1deaf88b8259
3. 852b482ae2408e2483a8d83010d513f1da27dec02842cdbfcbb92701edc6a606

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.