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

ae54372274ed2ed26f54aafe026f9ef2037fa1ffea2d52334eef7efa0ae32673

Seed

fd27b5f77000bc2eb93535657de517afda00b9c528faca01e2589dd59eef2180 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

ed726d2778c23a710795783686c70897

Commitment

Batch 54,324, Merkle root e43e2a2a34acbca05441482f51213f7d21afe24ec839292303a78c6d0dbeebd2. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 108e895b38fa831f0254c91d3b7ab0456215be11d76cbd66c75c60cecff61ad5
2. ae9328b53c070a8f3bd06e7727d7143ea595366d868612ecc0d281717b3c5124

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.