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

6d4d8d399d7c33286b5ff6637362d5049d432228c8bb06d9a2996abb3c44d676

Seed

2f34538cc7926d7fbe5cd54237b911d401c014af0ce41cd8602469b1dd5075bb SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

2e2b8707de7674bafb65fd1bfb9783b2

Commitment

Batch 63,346, Merkle root b7e5d59442c100d31c50876fdda57cefca9941f9c7738ff2b20befb770e3e883. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 9174cc8568af63b472bd2f0f4715b40d87a26ede79021cec6237e54ee187685c
2. 909eef27dac032d725684200441730ba9ad509628f052eefaa0abd7cc8db2059
3. a849e58c0d0d87acabeb1f7894351eb7f10885eeea6bf03f526d42f537ab860a

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.