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

2d6b26de8bb844e5423a054aaf03dbb85bcc540e4c13ad1bda1aa3bf8ef031b1

Seed

efeaf0a51eccda62fccf50dd541e56944461f2a535f083d0213d6666742507a6 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

fb44eac1331afebf966ce5ddd32f29cf

Commitment

Batch 63,831, Merkle root 145f068d87176044ed529d41420d6f300f30620ee0677a313af7a379bf642c71. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 4418d4a90482085c70fcaf65c15b6c778887a35b8fd20bac2a4d28959cf04db8
2. 26c15770aef4e93d455f949089fe8ff6dd643d7c608a84c05094cbc7d50c47af

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.