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

f8b7fc0e4f5623e710ed4a7aceef2e1c97a416974b49cf87cb58c88d3c3a4583

Seed

e64667aba5971d7ee5aa68d4a014c09ff733713f4a47078d42ca82b35c78607b SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

c860dfb18eda80d284c0fb150865b9b1

Commitment

Batch 72,901, Merkle root d43b50fbf9e50bad398bcee95e07857a4e8b7680e832632e4b4d2fc23b8b73fc. Recorded by Degen Protocol; on-chain publication is not available yet. See this batch and its Merkle tree

Merkle path

1. 4a5b2deccbb16183b422eb0cf27d7368df3c6f978ef1e529c35c7af08645feda
2. cd780a3bbbbdbab03fc8d4580ffa880c43f9407446311681e89de88dd0bf6664
3. 7e8d0b114659d4bc82ea23257e1f1ac3bef78ba0e235f08a74d09e9bba91c9f9

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.