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

6487f7beba259ef752e24bbe2768b0dee6386b087944b5f97be40f5af012fc19

Seed

194b2445e59378cb13d2077d560a0d205605875307c631d7c52fc8a11b9bbc9a SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

7d8cda9842a7c784807fa7864f3d9c5c

Commitment

Batch 59,593, Merkle root 0b35a982efb5ba67f94e59283e689ee0e1be99438cd2b340dcf4e80657b167c3. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. b9407714596cd62907ccfe45f214003321fad2e0e0fae7be066ace870e98f3b4
2. c6aa21f3aaa7e17421d854002d5d24f8a72fd68ccfc4f702dc7e0204be74a310
3. 51f8efa3af42494f5dd2966c119ff746c95c7d1ac0071c29b719f5d1b6562adc

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.