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

dc6e2904424e3948f3c0e0f8d16bec9985ec18f363dcbf2f85aa9746533843cb

Seed

749481e26d1328dc7a326b2c6d047c23d0be8c36aa98807b745f1e6548933102 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

24b10d3de0995e7162a2c1533a59088b

Commitment

Batch 64,668, Merkle root 3ff8a8af1ae715981f9d4211a7d4ea2d33130610db6d23df9e715604341c3f81. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. b485a820a036575bcfb8f0299a711452eb55e8bfdf05c4acf75e9ee3443962b4
2. 9f57575a13501f3b08ab5985895be5a03e6557e171673467666c285d2e1f7145
3. fc3a08cbc7df66d8495f3fd81bd3415b0989ae4e293cfbc460a254cbd37664ab

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.