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

fc20d636e44a769db0e981bbf93dcd0da0b145b74390cdceb0fba774b530b75c

Seed

3d3c825a95275c245dd15f477dfb0509f25a05646e258afe638014b35a059a81 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

1ed3b116ca36eccb43eb212a3333baea

Commitment

Batch 51,315, Merkle root ee2cfea37ea0ef65d774df15b092cb024249093972e9c30934018ce897eafe46. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. d70fb1f60d1b47906fb730184bac9d2af6d112068b963b2ad0d18a2b57be0264
2. ea3f1cbcdec7693efe3dadca79cce9ea3adb2d09040d942486f048d26bf6d3c7
3. 80cc6f51f715d9f8328253bfef8e4133ccc0edf38a6907f2467ad3b5d8d549e8

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.