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

31a1244ce179713726cbd457d24d5c6158a5a866a6278defb49359b65585cf3b

Seed

e6d103c960f395a6531ea253383c9e8585912369e238c49f3e043e8e3bc37117 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

8a31009dbbf7366792a24560a703688a

Commitment

Batch 60,619, Merkle root d3eecb6eabc486296e14b7e90d1e1583ba69f51cb9db0dd5548d89fc8fcf4ffe. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 9d51150e9bc41389aad26111cd2acb36b4dc6a76954213a7e07478011285251c
2. 9505e0df728a8ea52753c6b5064a6d9c038bee47b27702a76d5e856013259070
3. e95ffe93d051c24ae9a20842e38c4237ade1e85024b60c2260c6ddf18ebf9011

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.