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

abee3a50a63e994257f949cbb5720dfab7abff8fad0d9622650f128e6edd104f

Seed

e348d9a18569f76b016e92c0d10b2b295c890f85775289556cbfafcc1f27981c SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

bc598fdc3be091665227bd18678c0d03

Commitment

Batch 58,062, Merkle root d2b759afa29819b6c1bc811ab6bc84e8b46459057c4144ae31803726b4d70f4e. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. e325f1f1ffdf51d29ae7a58ceda14d00db14335d8fd9e282576135d6d401122e
2. 237bac8882f0f63b04cf88cd4992942a1243a0cc4c27eb84aab9636f97cd948a
3. fad45fe9fdfc498fa054f71fb131fa0a0daa17ab387290da89b4594dd9671c4e

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.