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

caeac378c2da0f7c1a6ba5a79aa672643eeeb8b1ee5ea7fd92ba5c47d25675be

Seed

13214e8c72bf019a1d186c3325e1e95ecbb2deb5aad0e218ef710a2f8a6a5610 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

9428e2c451bba818b79b29e612432750

Commitment

Batch 55,296, Merkle root 4909bb88e05fd2dae0c4fd0c45d25bbab12df3f39ab270df2ae3340b8f311d29. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. be1fea01d0bc85523e9a8d5dcb6d9d9b7d21c89f5928d98c37d1a0effbb5f36f
2. 0ee4a343e7e4fc6dc929462735f98bf32a5cb176098702f294c266d3b1e746c5
3. 329358e46b4ad8402b40a13b438c638c5a0b476a17639837b7c02127be615581

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.