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

26b7dccd0c668e8280659824fd872656e2cfc9d2dd80f85c49324f03c21da8ad

Seed

0212c275e1abb80916494316e64e97e0065fde926e4ca3a8b927992997009e8b SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

b7f49ff982c94cb0cc2d02915c77563b

Commitment

Batch 73,065, Merkle root ed61aec14c3c94310c9a815c94a674c7d314c68553107102286f621336e9a18f. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. a561ef5ae096cfc39c38c6281b78555f3c7b30ddbf8606cde2c5b2bac60c51a2
2. ecc5e6f249edf183c5d14303287b5cced02f406ffa96da805e81f85dc28dbb54
3. 6ac43ce19412b44c12394cd76c6483bd086bdaa9d31d969840bb3ae19518720e

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.