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

40bde79bb0058115be9cc924f4ec990c1619a62112c1e2a146ba056a6559b7da

Seed

0e1fef989abbea9e0ef0049ce66448f2f281d4c0310ced3afff4029fc18c0f87 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

c63a6276abf92de643a73dd77c16de01

Commitment

Batch 64,086, Merkle root 29cff13a91918849f63d9807bfdb404163ef40364ffe9c7d1f6a85deb0c4359e. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. a0c7001a313d403a559be8dbddde8e425d84875d29445e70311a154d9223fc26
2. 23226e99f787ec1b6ed93b70b1b12e40d3424631b14119010af4a6a7ce4b36a3
3. 2cdc9564e268e0f8d00b50654641e1e7bdf4cd9a7a3f03d8d05e14c528761fa4

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.