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

f3b9cde07226ecb3872267269b84bee45cbf1388a8c249bffcd9c1893bfb8d45

Seed

04772ca1870afd3eed74fcb44f20a1022b6e25ee12e05a7a6f85c5fb984500a1 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

e0a091e7cd3994970652ca53fdf3ccc0

Commitment

Batch 48,212, Merkle root e84e9ed0ee561d45f861f798454ab649c1b55ea00658f931824ec627e0afba51. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 3c6042d34f24780a0060fccc300f72e6677454ba46433a87e4ca7ef749ae8785
2. 967413011db474fa94c91a488b817f836db8fea39f6fc40a1f09e62120a422e1

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.