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

aeaaac43ebd2f929801e19428dac1bc42edf83b9afa774847fbc31c3bdff4eaa

Seed

3f033359d71f0520ae5e967798890b02524f8ba51bee5b2eb54da978fa64f5d1 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

518cc8d00d22fe63807683fbdaa97f44

Commitment

Batch 52,709, Merkle root 5e63f0fe509907ba39f00a4d9cb5f22ce3cddc4e049bd80a6f18d322a4ed377d. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 0da445973d9b7d3def96bfed025f5f1c8852124ad0afcfb4801778da7e53de76
2. 7a58842dfb8889c18c99be0bb06b94724d470017cab7adc4e873fc668adc4e11

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.