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

6fff8af016d1ff3e3da5128bf5e051d2371f7cb50b9c766f4aee19eb13825b4e

Seed

04f65ffd3750c2c03e19d9a031fe5237d0f2e6e2cf9fc03d460d9aa47d18e0b4 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

3ead749bebe55e564656167dbd2d5c9f

Commitment

Batch 64,265, Merkle root af274c5e16fc61d52ac7db261938847acc10655a661108211687ba49b3acd137. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. eea0a3f190fac82c1f9b9303dc2e9fa32dc80aeda983496fcc50f9b82198dae8
2. 73924167efa3aa4903ff9dacd0f0e55fab98f7370b7751d018aa155b193fbf2c

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.