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

21132982e9178c920c6ab320d8817c04882c07594b98195d149292e767145b3e

Seed

4368dd438e0fb6ed1d7296017d860ac701845a45a602c1965277bc0795c54aad SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

205ace53f4bf7a4aea52ebc70c76c044

Commitment

Batch 52,052, Merkle root a89b0498a32c8891690f26b482b16806a69865ff4bc9233993a92da4e8da0e2e. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 09f78d6852c4999c9e368a3e92ddba1bd768f6a25b9f6520d481c260ea1fcee3
2. 9750fd34b605323ac3455fb4602f4bbb36609972b51c48c64b068844cb73aa05
3. b3890adce92016db5d3f15348da19c8caa1f872fef1e2c941f28773e85da87f3

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.