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

7df80f130ef3361c02f3ffa5faccf566951505cd65b504db1e5237cb9470552e

Seed

d9b1adbfd5842809f3ee28fccd0cb15e85177e47e6fc010ebf883937917b74b9 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

ef6f8282a8c1ce1fbd3637416ecf9690

Commitment

Batch 47,126, Merkle root 9053ca73cd756d7cde6a8ba2106846fc426512d0633811d7b16441c9524ccd52. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 80a2ef2c3bcafe397c3258d6e02a76644d7ef5a0269f846f686177ea36f79439
2. 92a113a36ebc5d1c8bf3b10b78844f479b4f79ee201270a670e9863fd5b721ca

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.