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

4cf7a25358a06a9a65968a5738de54ec662bab7313d3315080434778e97cf418

Seed

6129cdfb493464a7fbbbde1b9687a83dcaf5bf41396471c708ba776e112db959 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

941e2bcc5e290804a317d470e7e94e70

Commitment

Batch 51,199, Merkle root cd78d2858e7c702d0a1fc6b890ca63ce97ee02f02b83abdf727751d4ca97e1eb. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 03791325d4d29b9b4607f946f267a38f70f6cf72c85087faafeb0665f18e615e
2. c37599f6ff25c053764ab26da6e7e71b32d4dc5589412e5d1bda7b5f680c5706

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.