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

c47b6b8fcce72bfb9b7edfbf37f3c42085789cbe62f66f54e638302e00e2ea9a

Seed

3fdcabbf7e3f9c8691e9d5ff11d17915a1735baabaa55705d5ed88937767cd59 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

1073ba7e9b9555923dee583bd5212c59

Commitment

Batch 49,019, Merkle root 51c4cb922d7a512e9ece0ea37d57f0143bf030e1f4386abbd1f7c9a3133e9c53. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. e026aab06fa3fbf84658895598d68747ebf751ad4e1252bcaa74713451e5385d
2. 5d83e494f33c865c45a72f879b9ba4e57a572109a581441aec23db1e14833401
3. f74ebecbfc5466f22c0929ca64865160253b3d70a7f33aaf1f996eb268d84412

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.