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

b75f004b28418a51f33be030b77bd531e23c2eb618b44ab89cf7de1e883aadb3

Seed

8da01bf002bcfa41974c4b5ef38aafc199a7a1f078ca5cada9743fa50bb38c55 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

c10b354086adfc72d17c61e78565c0cf

Commitment

Batch 47,350, Merkle root 976879d51e840dcfb9e1aeb3a9bc54154f2bd7fe9534d2e8f4b393cabab7a979. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. f223e989adaf1d103e7ac5e88fb2d1cd48c714eed2bc0f69e1bb9b5eba8be1fc
2. 476a925f6a0aa8363098e95079fd2b931db74d63d7b3a03c39b7fbe87cc8da43
3. dba9b7e9b3970672137ef0c70ab99b6c623e172dc352447044315a3c9aef6083

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.