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

1a45c89af11bafe7fc0b7a98995370650a852620173b22080237e7c33ec97792

Seed

0f3e85d5fbc64c575be65679b0c8c655b9eff8f15f7117d6cd92c6effd44f656 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

35c9e80343c57a53d5ab07420243517c

Commitment

Batch 58,386, Merkle root 32dc5ca568fbae277efde3c32a582ad471d2fee53fe00c013a06b3483b31d4b3. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 7a7bb4f8fc465fe71c2de7da7a3b9839652ed1b73d609b1e48f0cbdcfc65dc4f
2. aecf7d8ee7a49104543285094d43b5745be3d8ee99dc9efc6f91410e7ce9e0d5
3. 14a563f3c73f3522f0b21338ae32ad4143524d102b64cc47bf7e0d0d3f079570

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.