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

226154b0faa6a5ac08f0cd6f5d9423bc98eaf960edf0b39f553633cf93c76f7a

Seed

8ae9ebe987ebd6f86e7d92a6942d31aa73ce4db45206530d9989dd155fe99694 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

62636bca113f398566fce8ce588dc591

Commitment

Batch 50,506, Merkle root 263912d701f21c94b7f3a0a72a836fe6684174f8a9da73c98a42019f8f8d1c93. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 11bc51acac0bb894d82142fa03cfcfbf2699a388aa0a9becc40ce7ff64cae914
2. 778d112376547894a7fc647bb4621763f3119e2febf519169511075974c431f4

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.