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

3b4b531fdd0ddbea46d42bb1fefdea8dbe34052f17ca5c3d20015c4d29c7df69

Seed

ba33a3864624b19f2262936ef9a73b492a068e5df2cc842962d2c6b27b658f4e SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

135b51c7eb122e4d9731ea6995909be8

Commitment

Batch 51,819, Merkle root 904df3420e5aea5768f419e73f04d89c4c68c14aaebe62510c736784b32dbc0a. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 0fde7f7b5668faadc3a8011840b305b31c7bd2704ee8a13cb7938f47672308da
2. 5155a70ad492e59cdb1da53a8672c65c58c8d62863406cda76e40baee0a8a48a
3. 72cf18728cafecabac54af1213234cbd1a94c26d83d7f038b5ecd9cbe2cedf0e

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.