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

1a3f5402bac06173b13d6fb85feef4a9a61146510186addc75a52d866bb5627f

Seed

5d808e49d07dddf0d23d9d65b99f32b63c061bbf652ba84ba12471b59398736a SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

210e7aae04b6049e4abc8d338c9465b7

Commitment

Batch 53,028, Merkle root b7983f358b83c9d4f7d1c9c800126a05a6c05d8962c26ca2b58bc920898ad23d. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 1f65041c41d77fc3e6232e640ee865250d41bd9e3a00992325fa48ad16ce1b2e
2. 8313adc26b18ceda60d08582af16b7976ae9a8a9013abd367c96f5d9c9636f42
3. f9792dca88599811b78c5bfe4058777080d8f0eb068884ae7cfba6306b62378d

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.