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

ba61708f6fe10a1e65e0dc579cefd295f80de7b0e0efc814c1f0de7e3fe51fca

Seed

75e7f0573d04a9778061599be25c8eb2f116d9ae133f648247c016dd7dc4c1c8 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

e5c898a04a41da355ad69f3f63564286

Commitment

Batch 60,557, Merkle root 4f381b5ce5ab3630bbfc7a539490c00bbc4b13215999753802de7db592d6d382. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. b1b4083db2e95c1a58bd2e068bd24dd25b616235a005db0289b6ce50c36d2244
2. a63766129968d4adcfc57c946e8218db789ad443e4838a578fd0d04291c6d932
3. 62dc29492974416468941774db56a8ba3227a4882728393f1dba715106f9d78d

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.