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

7156950b5b505d17dbe25ad9865f9dffa37c1c69c4a5d3e4cc916c6ca99f8908

Seed

c9acecec8ab297d41bbeb797335b62bc77398b6925bcbc65e328c5545b0f8708 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

712127e55cc727eac2b041197032ece5

Commitment

Batch 73,415, Merkle root 03fbf46670b14a72e99cb982ccb4fe9586491dffe3369f735044089c2abba280. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. d03ca2b0b179198aeb4ec60cacd7617e6c9acc36884ac67f981a341d2ba4797a
2. 05e504338d4e43d509b0689b114d5f1ba28aa8e334770b0ffe86d09cc337eedd
3. 7a679d0de37e7294d8bd8410841104b4e1d9547c9545d638e7cadfe30b4fdc40

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.