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

cc29b34a53741aa461f2be048ae5b6a78e6e290ee616739968089dae3413da05

Seed

dfd719cae0a0016e935ef9ffe1a2f48b93084d33cdb5de91ffee1b896b16d476 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

c39291d9b83071afa7dee5354b8bcf4b

Commitment

Batch 53,338, Merkle root 1740f2d2b2b2fb191863d30087f84d1fa56a2f6bc2575d7efea8ab525f2a1453. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. d8c495795df048238825f247374e74d2206756e2f47d97316b5eaf0de3e8f222
2. 1512597d4879b429ae4c0ec1bf08d2b0babe08c2c9bb7515e48ebcf650c1a28a
3. 6ce46057dc22f872a6644aed3d7a464a5ae3ae5e5d5c251d9cab62dcf8b5e764

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.