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

1eed9eb2addbad2d7f9c7817926b0e38044df3edd8dfec96f2b5d5c4750e2392

Seed

97be707f32e1802d5d3e5d2eae75c8435b14005be1dac87a86bd47fd397e2136 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

e1f81027099c3e93668311efb84e321a

Commitment

Batch 53,423, Merkle root 37b57eb2d686173a08f7604ef1a31f919342bce335b2a6c852bd7c2b6ce77b12. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 6cd05e854c39cd572b2c342b8ff87dff5b860a63f1840082471e4bee39db7bfa
2. 3a15e6746e07a5693dca931ca2624c3e97b736c71ae14c7eb5312350f56636f6

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.