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

e38852428a0629d9aad202f94b67aa030eccd07e2c8382c6d7b514df27d29b4c

Seed

a1abe950f6877fa4eb5180d68b0caa7d4de0e061708a80914be42b1a364cc11f SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

5db464d273da71bcbad107464fcedfeb

Commitment

Batch 68,351, Merkle root 840f8a28e1a09b4d8b9d091d6502c27efd5292844f092d7c84c1b80f294fc62f. Recorded by Degen Protocol; on-chain publication is not available yet. See this batch and its Merkle tree

Merkle path

1. 63c980a9e5a8a1a41fcc60b111a06af670d2dc1693b9720806a0044d509dcec5
2. 27c5a4546af505d5ed25c2606faed69c4f87655a470df03bae16f8082bed91f1

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.