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

af34000a97db7037984d4fe23e70fa9129c7a743ae352732e71b6f0cc3713283

Seed

2f4b7b3539ee310c4e83079f9915e9c0002a1fee51589558703c026d0ebdc0ee SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

d8da04446cc55a7c4035c235a6baedea

Commitment

Batch 53,575, Merkle root a7153631fe834c8ed53acf695cb00e4997924731b9fe265b5538d60f7aaf5b32. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 2f823e9649aef30b1faf353a62a70ea61b9dac4b7c7a25951abcd21ab45879d3
2. 854d6fdaf03346e31a5f0c8f885e692adf0a388ae2d6ff926e3e8e40332a0e94
3. bf5626f17672e36687bd576d81fae032e7a1e2e29464daef5d55cd158616f253

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.