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

9b1efeb5dabb3091dc89e2aaddf6f3d7af25f9c4692337e0bec89998ab422003

Seed

a8a9fb003774dfa46852d98d2fae7dd8574b0a1237ce298d30b615af047fde3f SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

8ef8ab7d247d438f54ec29582413451c

Commitment

Batch 49,520, Merkle root a1516a91167a5ca4dd795d990bddb0e9b5fb6f9224fa508ca4c4b131dbdbacfa. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 9b472c0be176175e6591ac85f99a2849cd1916f2587cf7c456d6cf3eab07715e
2. 7398471f274a5788bc2e67f12e8742ef3c913d49f0da9081ad510f46e696d934
3. 20e7ea4b1a510edfb6d51562d2271ae008c6e373ef67a59fcc9de4ede8e11bcd

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.