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

9b33985047891fcaf9e70af99161fff6d9719f7f4bbcf669058b8fda6f0687fe

Seed

235a5203a0958d277028c1d7acd1ecd1aee815ca9daff2f4758d90b2b14ec026 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

486da89d3c2a8234578a927b6e81ca3f

Commitment

Batch 67,064, Merkle root 9843c36f4e1d5055a419a0d31c7aa0bc36d064f61bc6eca149f21b087de20136. Recorded by Degen Protocol; on-chain publication is not available yet. See this batch and its Merkle tree

Merkle path

1. 6a59f5193fbeddf83e42b107bd5f321e95f00d60a3e484cecaf106434f4c1ab5
2. 9f529e959d6db1866f550c9321751e5d6185f33373428d6d2b419cb9f1c05f0e

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.