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

c0eb5598d1a1a1738aac3b7102388959f14646be04aa430b1e4f59d2984c3d26

Seed

069baa2f157b0394ed50d1e7b3894abaef6fc5dbdcc04baf028b0818a6eac3d3 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

d8377937a0306348edbd9d3fc2cad7ef

Commitment

Batch 50,037, Merkle root c55f3492d58e2c58c7ba2535861be787c5aeec558b814402045f4d662e19e3a7. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 80134076d60826dedcba37fcda7bc2809f41ea67bb38fad44d25026108c0a977
2. f335500f1a05eb45f179236efab120b04bd961a6b76e6e6e9eb78132875a8503
3. 179a8909d6d527e0f759ae5cd03e6a8fde082a36cbdf0b5a6c7f1dc577262c5a

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.