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

f9f3fa4a7598a0298ce41ba989a99469022d090cdf70225bf329690e575bbf07

Seed

19e68821b5bcf251696702116e5913b3cecd1615a507559033817226f729f86e SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

4a4bf7f3cb1f8add228010e94436e043

Commitment

Batch 47,620, Merkle root db57403d17e0198ce8f99243ef39dbdc5de1d04b6f763af087009e56acff9241. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 665a68363739d1b67cf47e7f7beebee15b187b193bc5c10cbc77ec82f649f97d
2. 8caf72d66999406cb12c8d183e677c0c84cfd9f96c8ee177d3ecc7d89f8ce64b

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.