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

a35658625e7fd707a4895406ad26ea5c199e3475ba875de28a51203a8f4d158b

Seed

99007e4934a5265b0015c713d3aa7e1499364f8d6d3890ac08cf08b1c7d77e76 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

9c8ddd06380920f2cef85f65c36dfb08

Commitment

Batch 64,207, Merkle root 05dfdfa6011f45b4665a595ef7e2106f58f818388a32b1a08f3f0c8aa1186574. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 1d29f8d33eec5c7c96bcdc9cb0f43e49588369e724e030a04bd7751680dda011
2. abb84a4867cb727d5cd6d293ace2a81eb1dc88a3325bc62fcb11512b707effad
3. 4477ba2a6872ffb05f6f27be434c899f4ac1df482335523b3ccf3655f07498de

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.