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

58db442ec53f2f875136127c54608b17efa8b621f70b73453c520131659ead94

Seed

393953a1f7f332d8c6482926fc129295a81056458564f665e723be9178cfff6c SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

0339537f23ef9d4fde2eb138d0cd1111

Commitment

Batch 60,969, Merkle root 51473f04ca3916fa655d0d2932cc5b3813151059ed3b9976c6506d51ec891ac8. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 91bc39fbda0e41c593605d3040f5824e9eef672d64c72a3a2ca8a1c0e8207941
2. b9848fff1c31f7c7f80047699cef555215fce633bef4292c04b3d25ca803bbaf

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.