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

e5ab4955a3635bdd782b3a559b9f1253416007b5f99b9bbafeaf351fda939be3

Seed

b6a5544db61a4cfdda55e18cc6bcae4ef9cf5bf4f0a1fbd4d67dfdb6f275d149 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

a0f4867040f8ed9d8c37594a8cbe2265

Commitment

Batch 70,975, Merkle root 0d3f0ff1d2d7d6495375e82bfcbd25681dd3d51938576d57739deee992f000a5. Recorded by Degen Protocol; on-chain publication is not available yet. See this batch and its Merkle tree

Merkle path

1. fa78f07f216e4ae9ed60fea60700717c02d9a09795aa2a6586b5cb937f8f1f60
2. 8c93d6df700867c70da81f6ca94d655ef3c20ba4397ef0b16de5054fdf29bfbd
3. 839e6d120cc982af53805247ed6b4c030f2490341b92a8e4e71bf00f7d994d95

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.