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

523a356ded818920652a5a12c48ad86961268e285a775c01662b19ac266626ef

Seed

9fcc2473ac7d8007fb96a1b2a7a09fff1f48a38612813886e5e4560328c3740b SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

d28b1d338fbea8ccd4630e5714ae39a8

Commitment

Batch 61,892, Merkle root 6ea342f4b22dab2292fcc3f5c836e6aa91d6508f3435c9d4fa6f6ac8744c5ddd. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 8e607920e06feb96a8d4b9e8ad7bafa165bbddf2282747153c87b619c9f51ee3
2. 4e83a1a81c5d211bdf5c8fa809ddf0ed53fbdd001448f118c78e2002aa889671

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.