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

2e776e01a6ba6568ea3817691062c4b847797d600d15cf0e34c847680b4ae350

Seed

8500a4e16a5b4d57a31df70289466eed31a1ac3ab7b6692b3cd2d7eae851451c SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

b12b81b6e04f2862284abb8ea99f14a5

Commitment

Batch 67,103, Merkle root adc771e736e64bb13f6b8a2cb8d56c761d73c018f9ec3b2471ca57b37faee5ab. Recorded by Degen Protocol; on-chain publication is not available yet. See this batch and its Merkle tree

Merkle path

1. 2e161080ded78682e567398af3d4c0ba9e8cbd73e283b3e141b588acd6f9fa0a
2. 01904fb45fdf08a4c95bfca087d169894c4f70fdadfd61763cc43aa904cbc837
3. 275ecff98ec076642e31c89ddfcb343e069eb533cb8b0dae15a82b3b543f0513

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.