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

7800805e50a784f22b58fa0cc14b4f339ee2343b5df481ce9a78fdb2c25f92d4

Seed

71aef4bd9703b648da8e7e6386bea572e686a7c9d51cc38b681388045aa041d3 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

51ee5aae6116036bcaa2529443191c30

Commitment

Batch 61,980, Merkle root f369943d3209f8a35b76574ec82df9ace7b5f7f6ebee7737c0ae71a618a45d98. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 9617b7b5e72bf6d7f957dfc1a468387adf6dcd71b6453338e8206e73c3641f06
2. dffc81af7653a032f1231d31a8ac015ca95b74f42aa4bbd2cff5cca5cd9449a0

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.