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

af9fc1d28f5d5ee20f718fbdb2b928c5c432f1e8f98a0e20024bfaea458764f7

Seed

88697ced5ce12b5814396c016088f9c683dc18c2b989b07e7bf0e8d77d0ec915 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

43309492dcbe3f756444348274bb6805

Commitment

Batch 50,003, Merkle root 10a12d530b2275b5699e5108d20dfd4ca0b5ae19bf1bb2370c4086d955877517. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 4d5f23a9f00e4f4280ba19f998987f6f61aa219e6b0d927a711ed25b3aba7ac0
2. 08e72bb14e7fdabeaa849e635e77e185d1d1fbb9b8f8aad92eff4ae75409a74e

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.