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

44114dc44108115bda60030b0c42641b340177642f00623985ccdfd692ff9240

Seed

c2802927cc98230468284ff808bec2a9805cffe88d24f04c8a0d518b37ab7dd9 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

11a1c5ca1abb6ef518f3fca7285cd6fc

Commitment

Batch 52,949, Merkle root ac4ce57def8a26c18f6b75026f255f56b55a2025a9c9630d2338395f07ef75df. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 916f5e563ffe1734faf49d820979f7d9ce9cb5d03aafc966516e67e56d1339d6
2. ea187054a54eae93b0655045d863a0aabad4ea1c2c86e47da196b0079708f501
3. c0d7b10ba1ce6a3ff93f8390ba215bc6c1550e372c0bee7bf3c90828681f8c44

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.