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

b03a79f3816bebe85424ca14770f1efb951c963b3d516cebd95d6c1ed1ce0a1e

Seed

7d5bec7231cc28a4589801e6942de771aaf8fe21001dbbe0ab9ccdd597fbd0d5 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

5a9da051f760280a6a2a5fad10ee1cdb

Commitment

Batch 64,801, Merkle root 13be7466d986c52d1a23168f43c4d3c77edc218b653c2bdeb83dfcae42321e31. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 4b430f351dd77784d2e6eb6482b9d0312f4c5945219524d045e9e4b9696a691d
2. b1d2f5b6b2d9544b8279e1c2aa62372a79ef62c7dc8ca1621bf57d211b53f1df
3. c75aa1258792c7ceed08f161af1dd37f846bbe3bd2145c6cdf0b077378a2ffe0

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.