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

48a3e49cd4280dd562803947f4c6a3e59c1cc42bab5ec255495a4bc0c5c9e551

Seed

8c5dd2c6496675f0416a9aff107af98bb40792a547137fd3ff36f1ae61102a14 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

5dca9a4185b807af827f13b6f36570ba

Commitment

Batch 62,406, Merkle root ae1d8fe5fdf218f65ede95fdb8f61bcd8e81715c3f2642dfd5dd5085b53cbc62. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. bd676c3909022261096682cc75a1e7f53ec6fde36e292a3774bd50f641ddf6bf
2. 8fdba7d21ce20285dd035eee78f31644ef82e12ccb17f3d2492d8c42e77cecf6

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.