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

a59fdd5cc06b8c018c80155f0c60d3fa0ac5f2c9993538732d0f734126bfd2e5

Seed

28006170cc52569afbf1ec0d72c398bb93150ca48ecf2531467eb1a0834f7d35 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

cb2f5dae9000e0103791bb06d4531bd2

Commitment

Batch 62,554, Merkle root 2bf3f747392aae7572e1ad9546f8c1e898b10183cf7171c6bc77cbc12084c2f2. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 6150c76577a9c368b52e9a6efe6919d50b34ded01cb3c96addfa9b0b364b3c4f
2. a48f00e400483ca2041c7237997ee05195e34e2b31f5699b59ef91d335736af5
3. 60afa7f8157dbb659cf87899257f3bb87126fd63f1b714ce2d29c9dfe07b9e65

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.