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

418fe5e28b2881fa400833c8cd277097e075c1104ffda558e885beee9333303d

Seed

e611d62e72644204d578612549443c19cdd9bc7bc573392c3eb2ce68ce92dfe4 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

76d0c835ca35c1d9b752151aad12f047

Commitment

Batch 52,862, Merkle root 4b94ea10f016d3075eb75dd4c9d4b58a8e51832af4f96d5e9c58a4797cffe211. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. fbe8a4f06ecd32d8339918bbb24d4e3c83e40e05361276abd98bcc90edebaa1b
2. fdb25c494f953be6621ed613f8404f5364367ed15cb25b9d5feaa2f2fb9a36ee
3. 8165ae1d937b483af0b6811d004bd7c1b6f828eae0b5c6557516ea35996588ad

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.