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

514639c9cbcca133e26101facb14dcb224247e9f4cb11f207772b4a2c753e5b4

Seed

0fa97fcd61022e40f70920e2b1d6ca4587f3b6a5a82245e0200b5af24e4652bc SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

e353f163c62a7d300386940a40c17c6b

Commitment

Batch 59,948, Merkle root 7f112c125034d97eefe3e62912b3f15cc746fd3cfa905e5dd0d7cf4e85347dd6. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 4d0ce22dbbc72fc02d2dfc821aacc1d8df0511ceae2c452a3461a9d296284b62
2. bdf26bdaa08821f387520194fc8f828e5fda593a2c8fafe8d093c072c096d01c
3. 6ed9315453f75d1cb4f9d4379f17068f11f61f2c85c390a70e3130b4ca677be4

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.