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

7aa239d7f766e54efb4b7a4b9021c7cbbf8c2cc003909f5d2f16ed7a20820dab

Seed

50032fbc7532aeea55da2457bb00a6b5ecec63a3b1a21701272247c5dda3effa SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

040f08023abef741a058bfa7f1e6f631

Commitment

Batch 57,956, Merkle root 00889c1ab2607ded95ac041bee3f63b1589e19c8f9081101346dbb17aa5de2ed. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 016d5718ed1f86d22dc29fc7977324f156be3b4bec247f50ee3cf51a85970d17
2. 943d22fbaeac11b95a4b26cec2adfec94fb5127dfb928e98c36c4377227bb58e

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.