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

94028bf6031c36e50515a3b0fd8f61f9535e6af9454d63f74cfd7dac6f3352e8

Seed

85e4f7ef6f88f561ae1d5ec117b874203d888ab204d37ccbec731746eca0dcac SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

85ecc81095bea728264fc12fadd1f434

Commitment

Batch 73,226, Merkle root 00b8cc29b82e56322e70477b0454e102c89c21b6ab1fa2d1bd802ba5199e0432. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 55e10a5774cdc48d3efca377a87db09f334522772af1e2d4cc793c1cca5c2bc7
2. 42cd8c530f8c2fe8e0afe9e553d8af6ea9710c1f7908efbf37bc0d5f5f2bdc63
3. 36cc620cbfac255d98a514155b6a7eba60565a335db08a18a7b47c08e8468db8

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.