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

adeef4077e5664858b5cfad8e9917fb7dc097f8080d50e274b4d816ac25ad6ef

Seed

19e42b6f568e4af4ec7661ef4825ebba29d9c03aaee7806889a2af4331e09b16 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

5fcc2bd44ca7955f5dfd91d71cceadec

Commitment

Batch 52,336, Merkle root 6d1ad95c3d6e7dfe59d1ea5e15b54a28df0bca75ef31f549cb6fd23270ecd347. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 865014a2a55cede6003409f4ded6cd149634a102364975836a77fc1188ce48f2
2. 443898eb6f91576b5cda5db27021630d124ff10d875a93e4f43f4e4de2aaafcf

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.