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

6f9da5c012da7ecdf67c092095da94bd80b16a80efea7a621e3a1a4509f31fc7

Seed

c0d0ba66ccd8592360d4294dfdfe1fc9d421affb19b498849cceec2e136441ca SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

af45e18bc1703b0006ca77311fe49eaf

Commitment

Batch 62,176, Merkle root b417a7300787a0fcd36dc6ecbea2223def28882738f3aadfa5d9e4f2d725c7cf. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. bf8f06a5716a520e5511961ba414c22cd62c40df98bd926edec0e208db17ef7f
2. bf849dd5d8b843db7b2fce066ff2eedb76a2d5055bd80b6dcb911eb431bb5007

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.