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

d16523607ca7eaa54408d2ca5fb35f90c28d9b18454fbedb0ea136a440cf3dc4

Seed

af409bdf8aad60e8541ca656f8531d818d5b542290cf7f9768e0590878278309 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

4e049a74f3aab288609910e21bad84bc

Commitment

Batch 61,656, Merkle root 988842a7b67e8925ba9de21fc2cdb1066c0e9589557df4f8f44bd771bc41e253. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. b3c51f6a99eca98a4ccf4b3ac4455986e877fc3bcf05b1d13634a6e9deeaef17
2. 526c00a1a80807c4baeeaec6a4b59923023a51368a1343b1e88991cf73e54995
3. fcacf7c16051e4455d878a5c5bdab6e27a1f1c81c5aee811ac164af1715681f0

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.