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

ef3d6c85794c9acc81ba7e5f6b4dff48b7649c04b8950f28c466f1048616cb89

Seed

029cdd6241c2a1ef08e9fadfc137c0013d489ce3657045f56771f3583327c60f SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

1c7813925859dea3c4e5c669bbc3d203

Commitment

Batch 51,931, Merkle root b376b1d810f81d0c2ee39bff269d662a7ac838674be1400f62a5e36081b87331. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. fefea6cffaf07a4312929fcfffe055dad036100afbfcf8a2316dc0bd1c55ba0f
2. 1b4fa5a2672678d2bb52bd2a451858ebac53ea6472ec36d07f10fd9efb65245a
3. c69787eccfabd34eb6526256dbf871dbb3fca0cd25f398dc68e5427941523c31

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.