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

69c1ca3175ba6a15d817b3ab65f34f2ea4ff53e65326dd35bf31fc472ea8f9e7

Seed

3b47ec74bdc450272aae115ea313f1aff2ddd2bcd0a4bec547eddae209639fb2 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

68fb2d0b3ae9d5f4ab407722d22cff03

Commitment

Batch 68,875, Merkle root 3c48cabe7611dcd8cbfa1f583ff4675d72356e9da00bd2a5435638cba8ce119b. Recorded by Degen Protocol; on-chain publication is not available yet. See this batch and its Merkle tree

Merkle path

1. 746fdbac361a2e301e17495315ad3541feaf0d365ad8e642cffadfdbfedcc21f
2. 554cf8e52ae96295ced780edb510bcaa76e95d611dbed789d5d071288bcc8ff9

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.