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

87073e595e182242d6ce908b70aecf8394ced34d2663615294c6f97b4ff475ec

Seed

2946a3468d57e973336763259d2868942627d446ae2f8dc3e8756ca4c3eacb33 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

b5b332b72e8fa06b096bb0ae0d175e30

Commitment

Batch 63,804, Merkle root a8b6bc349089b2800ffb584c7a9777c646f05c818fc0e98b786ea2d57c1c1576. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 4b58fdbb1c5c39ee61e588a09503aa898fafd1964d8aaac971dac590426b2c7b
2. cce1ea1559b94c9e6893eddc1d6e53ad75726f53858607b82e4815691e019a60
3. 492b2467ce8366da9b942c9c6c4bfb5ddda0ecc8843d778347a74ec2d0bb9555

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.