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

8734fc3884b0845f420d7f0205c325d7deef70d4b93d4c780931279faa1b2a33

Seed

985861298b138b6eda93271605dafd75752bf087a010fddfd92d4263bcd32158 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

0fad3d68e0beadd9b73eb2af473cfc86

Commitment

Batch 47,735, Merkle root d29aa21085ded32c27facc31f73f3772922bebf02b35185577d35bd12e79a078. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. af2c3d42215141b1d83f232264302a848a0c2564286b993013ca6a00126bff63
2. 9e7e4f3b34c93651d33307ba44a1c4d16b04fd4a275064eadb69daf7c7d946fb
3. 0348b290e5e955cd62f1cb072703fb831ce2d5ab2ab19def029dc5dd795b6875

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.