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

a9b95781343ab7fac417aa6dcbe3227fa4ea7af14773d4ae96fa6a3c167ddec3

Seed

17132b2768cf6d558966a54261f9becf5a99177d72d5a5c1f7f230724e182b4c SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

006a16c54f4f856059732f5621df8d18

Commitment

Batch 52,520, Merkle root 0f7a19650f3f89995466cd4f81d95c8babea6be6a110a8a19d40b567cf2cbc52. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 66412f51ac9d52f43af0f67f3deed78fdda3a486d9f90fd91400558f76102e22
2. 32b7ec4dfefa9d820a2849008e40263e78fcde095d45fa56e6b26f5411f12018
3. 4340a7dd2f25f9de0b32a4061eae2a5e24bf5461a8206757f53ac438a98e0165

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.