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

91b5472c298e525ea495230182b65e5570458d3b8f5cc1fc47b5d02a303bf28a

Seed

c82f8e01085dc5b28960c226426d1b18d9a5ee8c855db43f4ce7cab48887d1b8 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

b76f9e5d009e459a757db894d69fa445

Commitment

Batch 73,183, Merkle root 33fd9e64e5e915922f4810401a6e9e8cfb5576af65c5e45f3d86a039f5d2fc06. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. deb214f93e096d0a979e9eeccc0da323eb95da6964b83c9ae8dd867dfc9e5b88
2. 2ac77d5bc5b843a496b534870d4728519c46a7cdd7c9a9abfe271a475e9a44a0

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.