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

9c07c8497f8295c2fa3c61d49ec2618054dfc66e70bee5a17487975c56f0108d

Seed

2f829af108043f5893290fc9e2673121221e3af165809ef53398d66c4514c179 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

9c3bf56989a16ea065222944c96ea875

Commitment

Batch 57,513, Merkle root 9b20b6e6e625c25fab296ed8f31c58c4077c26adbea1638265b7b407442d8650. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 4c50821087e167309f8970784d0e6ddf05620952a9d9d70f38402d7b03275893
2. ee50dec5e53528ace3c83e06f5822e8d1cbb114fd631d4c122c3393e9824753f

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.