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

9ecbeead1fb1d109331e195d7ad0c57de0dcbe945998c3e1ffd4c3611dbb43f6

Seed

f00c99e8e16dd1898a86c0037925fac1735930e5ea5755c6ef920c8a1699f54b SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

2ea1027deb32b66cf01be56a199be201

Commitment

Batch 66,206, Merkle root 7332f6011b7d8952398d57f620b20626c2ca071f93b859fee6c8189f32828d9c. Recorded by Degen Protocol; on-chain publication is not available yet. See this batch and its Merkle tree

Merkle path

1. cb1d7b265552c60243e33f2c9fb5f82da037d06e9875d615773e95eda0a60cd1
2. 07de5f53f99dc06dd3175ac9a3be1bcb830f5cbb1b3eaa7040dbb46ba71c33a7

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.