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

80873970655b613812ac26b7f99d2b98536901d6ed94a19557bcca8e6f4817c3

Seed

1afb2e3c2e734f13ab889579d68c5614da0d215953c0157c64dce5699c710bb7 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

146d5ac27b678380989f9b065750ebb4

Commitment

Batch 55,512, Merkle root 48afba0f1d34249fd93a50d4ff60273fdf92c76ebafb3bee6416780d1e82f062. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. d6d683e6d797d6aa2d9e73045c5216ef06aa524fdc8791526366872dc7da9ec2
2. 5ee8d6b245f7b9d578bb19df6cd7da1774a452306e1fee29f8448ba6ab56fe36
3. 60dc2edf1ac87cc44889b57a3ed6bf3575e7337e506e1854906f2945f8c00f10

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.