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

67eec5c2bbd667d4b2b86f2ee6d24386934b902b5f208160ed68a53df9e3908e

Seed

83a7644dc46b297efa1d2a037051f47508c92d2b86d496fc1e0f10f1bb9c48f7 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

eb3fb3eb7cc3f59e441bc1516a26deec

Commitment

Batch 50,847, Merkle root dd89a0a7e1dde60dcbb90e307e39979ad0b79e9b930f55c3f89981868c012c8f. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 0d2daf0e8ee5b714143cb17d557be583d32a7c006a7e3eab82d7cd1fd1479f8c
2. e185c6833ad8e6d9525a46e1565a2fa91818d878329aa04eff1e54cb25b4e107

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.