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

ad64ff71ef8714b0872ee2ad9586c63c2737c62fb98e63f2b87d3374710a1c7b

Seed

6047ecad00ef443477feec953b668c1bfb8c24b5fc75c1fb94a62e88ea6d7607 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

9e8fc178b6991ed722f6811503895e4b

Commitment

Batch 52,484, Merkle root 48ce6ac437e16d22ed7ca09cf48d4ad6c8d640454249f3d5f4eeee933ac79c71. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 40674be45f566b8728330ae7ba5bd6bcbcbee4ebdd5f911296525d7362c3c0f0
2. f4c98482b383bd246920d712d06ae65afc7af1886873c48032acb39d49c10dd9
3. 18809b9bbe3f2540a1cbd4cbc331fcb58019384f9847f4645de39fb446163f12

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.