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

956a5d07aa3bd5f41900313ba6474212988b20ccedeb0da651d1c96882c06f64

Seed

c3aa307f790113aba0015bf55dea768f5553c559cb39a9821e77eaa5693e0530 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

ef3d664c38db1c5321d82ad3114e6451

Commitment

Batch 71,865, Merkle root f82f4e2aa8f01fa046eab325df74cc07045b0ec62e64fc63909486eb0bfc8d00. Recorded by Degen Protocol; on-chain publication is not available yet. See this batch and its Merkle tree

Merkle path

1. b7d934fdb5082b39fb2e2767c342d0ecc8b4153f3500ab62be1c949cf17629af
2. f4b07597d06458ba43f45897915c8c3a260321a409a5075a4172ec8522616784
3. ca52eb138b9f0029cefe1e240af072b1fb71ac6ef6cb5d9881e6c638ba87d0db

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.