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

a79d1c39478a5807ea715593f4993a51b90b9425340a742695db7db1d630f0fa

Seed

822d01e33093708f5139f32bcaeb78cea380ed923f5b4c7a670cbacff0ec8fc1 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

b1d4dde04d7c73c6a8458ce2b5150105

Commitment

Batch 72,397, Merkle root 24ed075750166c99c184343122b41035ce01f68d2287e5c04140d17497da5edc. Recorded by Degen Protocol; on-chain publication is not available yet. See this batch and its Merkle tree

Merkle path

1. e35ff9985c520ec621829c86a2278bf028753bd987c26ceff5fda4df707ccc50
2. ada0a178e2de50a886d24f47d5c1b0eca18efe0b9c93e643fca4f09cc08c844b
3. ba40d050e2174b05283a66ac2d232f64cd4f412805f734b901cf5a6452e0ea6b

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.