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

50d3f23dceb5b56178dfe7f68c1011c8cc89a51f07123412eb2c8ede50db43d1

Seed

49018c767f0f1b769985a596d26dee5a8a0003bd117004b9c7abba45260d46f4 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

b728612736401aa332d7b7268fee8536

Commitment

Batch 51,985, Merkle root d71d14db5f86cc3ca93f1711ca1c2b791d549fe68a0b806c9048def37c663f19. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 3dce6e207243c300c795b7f8f4769f0e9c4014e9406e7c2d8918c0dd3d624af2
2. f2bfa81fabf59ad8c1041ddd613c24420e2ed617300cbc04f99c6b5a0775e430

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.