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

72a4e3b62b20add7b4eb153c44fee78ae8301cd4b3b20516335e63645322d9f0

Seed

3a3ce06e13018055a066c1f2eaf9f09aab49baf68cea7445019d9f01d433a1cd SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

dbcebba145ddef61559bcfd86918cd82

Commitment

Batch 55,013, Merkle root 5b197b94f039aa513762eab4a91ad75606a07d0284db7842bddc8976da7df78d. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 3eb1df1bd2798ebc835a63f280f1add6e6e24ef926e32a1e55d0b3fa18f87683
2. c3da05cda5ea193cc16ac0f749479794251a31b8aad49e8fdb7e6dcf12ad7a89
3. 13a4586c290d895aaead1d3b1cfdc233b890356d1f5c09de33db75cfbd7257c8

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.