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

125a1d114b14569e758110b2b7abbfd6a5de83119f1796134189f73cd5d300bb

Seed

06ee0d304de9ccc79c62978d959e838489f07056ce212cd5604ba2239deffc9a SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

c18940fcdfd11dd22d80603f3719faf2

Commitment

Batch 58,852, Merkle root 9c9fe371cbd9d57db8ede7785d853991087a676dac7e9b0b387e20ee34115e60. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 61039c74612e73c11dc7301e9d0289c1aa3590246a48d831790c3f5e7843dbb8
2. 129b3e5147823487e5af58d7ef5cbf069be63585c74a53f65142f8d207f7296c
3. 1aac74050872e0085a1c0523feea81c821b65f3f4238c9a453574c9bd9ac8552

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.