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

e257c825076d43cab30e70af9169f7100b90b9e52bd8164f6e19589c9d1a189a

Seed

fd055d2ed11b05dc51d88a51ff36aa91bddf2cd3c601ecbffd58a2a390523f77 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

f71357592a2d67893d5d68e3ab8884ea

Commitment

Batch 52,012, Merkle root 0074d47ea4b99b2c889466c8342b5b0d85169d9c17de18b13d4dd1a8d91d2fee. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 6d6e9e4ef8aa9633f796220721a864069537bf7ed799ac0dc6500f71b2ca95a0
2. df2bf03ae4787efca88af4e1a66b4511c75817b8fc5c591d1f17ab1a09cb4a08
3. b42a47962fe5c405c07c717613ad842bd04cc3c8e752154a49a88768cae2de6f

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.