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

28a53a4492cfd50b70fad803d25d4073f8f727ff62c70f7a76d8cb209e400ef9

Seed

8ab77787dee7b44747cdaec11d3dc569dc4816af59965c33ff5ddcd20d7c8e8c SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

a0d3b5f7f745aa7c040bb2479171f7c7

Commitment

Batch 69,820, Merkle root ac1eaf1b3273bb92e85a9476454977433fe7b668700a434ed761f00aa80012c6. Recorded by Degen Protocol; on-chain publication is not available yet. See this batch and its Merkle tree

Merkle path

1. 54861366e72ee0d3e22348ba7df953e991b417d2d16a44e191c4ede8c95c936d
2. 7a6784f3df1c5d253f1a18143586b1d564709f7202953dd8843246b6a85c18fd

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.