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

1c84cc403d5e4e0eddef52c4f9a8f00843dec2192a1a28bf360861a9a0b0247e

Seed

e78e5afb534eb41c60ee254a8948c9dc03a79d76fbc2361d15a9c344bd9ff8bd SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

d12e9e2a8816ff269460892230f455bf

Commitment

Batch 63,767, Merkle root c840d108521300a6518bc7e3aa2c2e1131d361068881fe2e24f015e949954ea2. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 1662f29602d7cb1afd51b72b9cf912dc2725a78a6299321e89da3f174a647cc2
2. 2335a23863aa8b60c469144401659d99e11ed7543aa9059198dc69e8ce9803e0
3. 495b490bd92530db72d335f6a3877182ce4c59d9b4e111c622caa43a7f40d0af

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.