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

781db6d18ac89c021d8e99743131541a5784975bade9f8bb20bcd8c3b24e1dba

Seed

832a5c219acad228a26bdf08fae1c7a0d3c6ed8161e9a24edf3e0dd54e7e43c4 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

e9c3f7746cf44c46785938c11c1601d5

Commitment

Batch 62,060, Merkle root c0f21f5db09609598de15c55181d925022c7b33d60bed9f3588447d658ada698. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. e362fe431858c659fa41941833243bf48b50cea22a6175d6c1bf210aa46eca05
2. c398df2d79b6be6be14335c8e1297ede725c3e4e7a805fc9eac7d898baac4cb4
3. 3f1517587f0e8b30d217b25c524a0109c1b2a4c6944cb1f59850fe5c9c3d792d

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.