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

f5660f1b2d5e33564b4046b60c43a10e7c431851a3acc8ae526eab05efb9dde0

Seed

7ca12df61e0a1c85034e29635f12e671d521e2c74cc6b71530c8fc1868df23bc SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

2dfcfc93063cbe5b8611e28b7f8f4567

Commitment

Batch 60,950, Merkle root cc97a72cc7ff0675a45a20c2232a45282c0f128d9a4b6b4b85739aa4c7e41e0b. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 57c0d5248b2990b2e3f0be49d0310c979ff05b2b9cf06ad33704f70185c48456
2. cdbe7dc528dcd7ff902a9f2fe73dbcf46b1b9244d4bc97065a196c4c9d5a7c64
3. b981267ebe37b210c8582996f14307459bfc5909e32a27fe265b2e75761bf5d4

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.