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

30c74d2d1bdf7d56ba813ba3cec7ecc35a42f7e29c9649434194248d6b7c7323

Seed

c1a6f0815bc141763e32736b3bbe0b1b934489f16f82498cc8c0de0d73309d13 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

7cc9b70622a79e2cb069ae0931f449ec

Commitment

Batch 71,786, Merkle root 2894b5190f1de319004dcaf7a166ed5992cb9d2ab3626c12b761e55f27440e9f. Recorded by Degen Protocol; on-chain publication is not available yet. See this batch and its Merkle tree

Merkle path

1. 0df6418f66bb5ca423284464692d1e63ed085e6e415eba08c4a0c82b3c75c156
2. 66ec63119c8be94ee863093e21233df837812c23043e36408dcafab9d27b0f81
3. f4a31e285a20a34cd54e58a31a49c8290771c97e82a189756c50087708e18608

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.