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

cf7bdb1e899eefe0ff0e85398cf8955142b40688013ca240337300b964e22dd1

Seed

7e7ab2b5ebf50cfe831e02114630afc4acbf03621917b77a7a18526b9f720e23 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

4c5349112c0343d96be5b872f7034f3d

Commitment

Batch 55,588, Merkle root 75f8132002c6d0d076aa0a4a737382f8bec84101a2aeea9e23c3fbf60bcd89db. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 6d0c9ce002954ba209091b8a790849493cd691490740675473e58b1fca70b9a4
2. 0801c8492f08515b907b83b7f39b090ed2b591d3f4955385f84148ab416e8528
3. ac3eafbe3dc2f4315a5107cc30d9fe12d4a5f2d752500a3f275a9c60ba0e2c3e

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.