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

35d6d9928b6b1b1da908fdeb5896100f225d03cfc282e7afd44635344c60ba8c

Seed

77bd7ab55f520b11969ca9bc1b5acf8467f3ee405b9400de7fec2176a69e7ab6 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

f7461c1bf4d20e5c91ff9e821a07c486

Commitment

Batch 49,344, Merkle root 8925812051537ebbd378bc4b3cb9077b54b530893c6837c0a855c537d13c7db3. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 2fb9c8ce1547d3e9ef4cf7ccd0b2c208df68a521dc901597b9899ec43f70e005
2. 564fc1d94045e379f0e11ecfbb6d5c75b8921af578db5214a1396b97f5639a56
3. b28997dd83cc1dcb21af3ef5ddcdfe41557b454066d7855cfff0dd27ea0e0c86

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.