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

7bd6d63230fd488598d13313bb0679d616d567b1653cb99d92dc617587510c1b

Seed

4f7ffc952f9367c923945a9757c1367c92f91529a435b71fad6fd4d8b225a39d SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

6140978510e891cf0bfb7c1d75100acd

Commitment

Batch 73,459, Merkle root e7231268e05265460fa0e41028eaf4104e842c996cdbcfb797bb2f8062c68d7d. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 24a77eced4f499e020c9914eb669ad2add6168606a822702bd76f5fd1173cd79
2. bd799c063b7f927c053677e8dc4d3e7d66944bbb1f1063bdae8cb57a5cf1336a
3. 8c62539e156b293b899a2a3d4d25db368b102421cd9a5ec4cd85fa4184f364dd

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.