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

4976c601eb3cdb9a8c02ae49021557d77e9553c9e96555a504350f25b9a3359a

Seed

57715ce2a16f457feebdc9f2754962b319b3a33362d1e5ccf763ca8ae45f082a SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

d91fac552b5f85ae1c3f6257d0840a9d

Commitment

Batch 53,930, Merkle root 6a32019ffadd087afcc4808cf85347b297975ed5b09e394281ee797fb41f6add. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 94812b07c77cbbea9278ac53a2f52cde005db014793c2fb0cd658f61953319d1
2. c3905c620083d3839500b3ffb32afd35d20e70daa6ab82a5cae8096a6dbe1f75
3. debf89fa0230faae1625ddbd72dcaa0fa8e89306e13d743d6aeef64d611df0ba

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.