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

4cc5fd5c96cc013e4a4efc374f7e51e9aada74dfdd0f6ab1b4473c077b4f19f2

Seed

3d63f516bd01292541dde26d293732d49421c66e9cf73dab89a6da6e3f233b12 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

40f551362e59cde061cfc1a572e29d19

Commitment

Batch 72,161, Merkle root 5023f09e0262e1ebb8f6d11815e64a2f02f504a1b28efa0c3edef66805b70e81. Recorded by Degen Protocol; on-chain publication is not available yet. See this batch and its Merkle tree

Merkle path

1. 3d0b62d5d2320f9f058ee98a95b5a62ca75ceecaff9ee43e3d799370a44287db
2. e3e6b846f5cbd0829c57ec0865976029c623ffff930fd41511ee452d34e38c18
3. 2844bea095c9b5055b24a8ff8b17a68291a0fcc6b316d0eb70013c30ea01d8e9

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.