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

61f188c60fc75e5d55d8cca22b0cafc784cbd0be048e64ae82d20ef23a84b246

Seed

1d29736f33e0333dd639db134515a69ade39cee0f26a8f01774ef07b070f1da2 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

757b8a693f42888461e7986b8dcf478f

Commitment

Batch 51,280, Merkle root 769235282a1586913e30f778bfce180329a4b8b4c6c164723c8218c87a0dd8c2. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 8d88df9139a5cf1c605439d831fb8068aa1bab79667321a96464a337f8c963fd
2. 3dfe83bf5c7768006d5d975763e1f2ec5ace5cb15747e8b73978df80e93598cb
3. dfd4def798352c6409686f5fc32ec70f87b5e5fc6f62a84a7c2a02dde32bf884

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.