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

19c52f9586ef19f7bbc1b7567c4884e25f01b93c15a2150acbf028a663b7e494

Seed

638bcf68a30296e6c19f2af73d698838f06e4dc0252989c97167727a93277345 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

644c2d3b474dc9c7ca7e2e0e56e168da

Commitment

Batch 56,342, Merkle root 644b15b234dd000f551db7d21ef095907590f5d61a7bfb8eb90befc50417bd01. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. ee1c989ab46eb0638678da769b388656de5ae0f3700ff0dfc66ff2b1812a6e54
2. 90557516371fe6372a442ef7a047b4310dc00cb1b16d1f5267db651a0cf14c44
3. 0c42adf8625473b3b5d4f88911fac59a1030e250c269301a6381ea22e0757092

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.