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

64ebeea3f0ffa1134898919f2a59f0bed9c26aa0f3954258dcaa1114607bda36

Seed

a14fd9ab4978cdff7fef7b8571175c06f627ac82bc7e9800cfb90ea480a5973d SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

a1ffa58f5f83c61d669ebb5ee4c79ed2

Commitment

Batch 59,712, Merkle root 39b403c90437610e925f8d926cde42055b183829e0edb83e8003b691003b49db. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. bb96d837ee01321fb24b3ff3da28596f1ae6b8226e4afc28a0fa85aa6b5d59a8
2. 2aec74f8408a1a0fbfe1a30abd38af66460e24de62f2a242040bd1197e648467
3. b9af43b03beccc239460dc3fff19198cfd7ef8baa7e9a7a7d9c17018256b18ba

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.