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

453d53755917cdeb7cbafe48b0926b99b0ddb159554a71774c696dd41f94f5b1

Seed

96369d7f9537c4deab0de7030762d46bec6ddfb31fe06a0368f21f0f761a2a17 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

03421ceb382d9247ff2c50f68c9f2259

Commitment

Batch 55,429, Merkle root bd5c288c360b39492444c320f5abb7896e2482d5c5f637a20f999f237191b1af. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 27d9e511f216e9b3be9d5f8e723772087624dc7d613607629449bdc855c422fa
2. c470c3c33e5cba7cde0e8acf4b67f0efb7632acbfdf21b663376bbf9449b5481
3. ec4a5e23bfe89c79175ddf2d65cfc4ed281aa70a6a8ee69a6be79806ecf28c2e

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.