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

27059e437e8e527c95ce5d13fd1dfbaf4d11ba81a56a61b2ddc6372192a62b57

Seed

c6bef7c0f30572c26dbda1d9443ab751717a2b0a04f2d168d64db2754f0a4210 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

564894f45b7979d5f38317df8b27d109

Commitment

Batch 67,978, Merkle root b4050084a7bafea784b5e7116acf50d02b1ec9509a752d2f019e88f7c30a626a. Recorded by Degen Protocol; on-chain publication is not available yet. See this batch and its Merkle tree

Merkle path

1. e75ae68b382949c033c4e25d1c09371f2edf9d196d51ce98839796f5ce9c3ef4
2. 51e4131bdb380ff099413ec41d6adf84bb22dbf7e241166e866794128ee13b7c
3. 9f7761fb07048224d2994ec6e35acdb219889ad3b05e379f0a1981c5e19fdf69

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.