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

7158d056482c183e918766ddf6b5d8d9d42f5e5c3b27852285b75ed002aa9d54

Seed

731fe2c3f2cdc341e164e7156606af3a49d7d9edf30fed9fce1d5078cb666e19 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

203a2198ba3d3877cd280d5acb90b44e

Commitment

Batch 60,248, Merkle root 1b76c64164ac0eca6561f3608a00c38aad768672211167fef7ea878f36582874. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 3eab8b238870af935ca6d5f1b0693c2df2e99f8e4ad5781ff72b156cf2d066c9
2. 9efc2cab8e3916399a02a92e7d5a90ebe704ea2eb6d60c52f2977f96e07adcb9
3. 7645a3c5ff2000ee9855b9aa23b38367fcde208d5b6b4187f1d9e1ffb03c5562
4. 94e90baa28061f9907a21beb1f58966c68bfcd6ceb0a5957eaf52ffb17256f84
5. 85a2f9d1bbdc09a4ffd777e56cf1d77005e8f1af0d7c5ba4cc709eefaa30c05e

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.