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

088dda1104690af74de8e1f37803ee0e922aaeedd688b8affbd872359b6ae557

Seed

c94e02a3220f905b45e3f0dba1770bd32f2cb59517c34bed4f5bdc2b703992ac SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

25d07075c7bf30c0a2259e68d849069e

Commitment

Batch 55,181, Merkle root ea3416c303d659849df5b672a24cac464ea087862414d5d2b2795b201a69c8a7. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. ccff02694cc8844b0610b9aefcdb42971afc1ca8d7ce1d218e11545a4806e598
2. ffff646fc731b31a000f970f1f60095a40432558be2ae0ccaf411996c139aeea
3. 3b9b1cf4694253c8cfd11e983ee08ca2db4ab3cb698f629346e6dd54f0ab101f

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.