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

c49e337e5183b8e76382e31d81264105e76833ea4aa75c45c49062b501fde276

Seed

8963900c59a680e35fdfdd88fa01ee5c93738c7bb1c76d035c6e1084c0a505c1 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

34c1c116e7573d432a5f2ce97720e01c

Commitment

Batch 54,849, Merkle root 6f780cf6d0154caef8972b84daa5ffb67d91163807902c7f6c82afb748a01d76. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 7339c4ba83bd5310b8ef7dce93cad9259ca3e14b69523daec5257e79ba663a30
2. ab15654fff79176754441237d838ddae42964d7b5f62363001717abf33b71cda
3. 22a2b20706dfd759029da4c8a5e3cb9364ced5ed2f88e1231dbe7b1d7b543a07

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.