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

4df83b53affc0132abe92e03eb789591e763967a46427f7950ffa3db0ddc4c05

Seed

b5046df008654af10c7bcdde382d49608f106abd612f75f4a84d09be47eaee0d SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

11c43619c27a1f35a756818296fb25b9

Commitment

Batch 70,344, Merkle root 4830291ea3c0cd5c2e9e17c74a13b198593348bdfa4801f777c6185b6930746e. Recorded by Degen Protocol; on-chain publication is not available yet. See this batch and its Merkle tree

Merkle path

1. b29fe92e4da044a2bb4662b4849c0ba81de25679b0b55d995f57bc90b3f1e882
2. 63e4f8e3dcc19b680ffb28cba0b26e473231b355da4938957fc515f95ca750e4

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.