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

8486a43eb63b4ad89fd58da649f5f8cb1e42b11a665b477263c90a380eb8370b

Seed

d31c6f499f7515bbd2417c66eb5a61a6c25e1ad0c60f7c325a7b54944da2af94 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

72fb85a216fa48fa5c307d60804e2fae

Commitment

Batch 53,851, Merkle root 3f14b4b5c01cc5ab12f4ef8159c0fc886a959489ba49818a710bd513879e7c3f. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 8efec2c7a66c49307416a9723c548ca469627982441f20c148c24f89bcda671b
2. cda6bf2e313a8e87356fd9c815d06e37715238ef899ebc5544ed2b7b37fac9d3
3. c1d8005e3243734c5a8e2bcf738d2353c38397d4dfdb993b51033ac66e42be49

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.