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

d04117d9bf46fbf2526b80f9fac7e793d1fd9a196e2f5a85e3c9ebc2dd6c705e

Seed

8890c67200be59e0e87fb92d5d28f4a6175cf7ce540c899683b9dfaad78ffb34 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

3c7a7281a55a79828719b265413fbdd8

Commitment

Batch 50,964, Merkle root 6075b842157153bf56f3fe541329daebbc25ad5e7d3ca32863bc5996b2f26448. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 38e99bf004109d7f3459eccdedf1a0a76ec4a42a46931cf112d61c466f7b1c3f
2. 50c678884ea3d110f0359c7df663535629cec3b985c4a01d041cf79653cc7c0f
3. 1a30b74f40f585bd74cf274d4a6867f1b9c87191ee34e37df1315e4491bbb50d

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.