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

bd1a77ed6aadb1657e510efa236610d3362ee54f36cc89cecf8e640b4710ead3

Seed

27a13133dc0a2db24f646546b727f36b64bfee3e40bfa7ac07c00444fb1aa01e SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

5939d5a4bdd8ce1bf4c329e96021f71e

Commitment

Batch 65,664, Merkle root 25cdf23e917fc3d836e37f706daa34cf2ecfc70e53049778815d9dd9b357487b. Recorded by Degen Protocol; on-chain publication is not available yet. See this batch and its Merkle tree

Merkle path

1. 44a7e0707a996f6c6188ee3cf4e0ecf1834d234f70dc43b6ae7f0fc0b05f72da
2. 268754d1b89f3e0bf3a5aacfe59a4cf7599c1088b671d3bb80418ad98db810ac

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.