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

d3439180c8fc0bdac1bf376f4abfc3b9871f6f63104a4783e9c72fa3706b72ed

Seed

0f209fa64fa4ae28a7db04d8944ddf5ee3ab46d48c9e54ba7d88702451df6566 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

e29f4f013232bcb3aeacfc7c2c75021a

Commitment

Batch 62,574, Merkle root e82e27656a47e0b42a5a00cb4e508ae2c481d6804cd9b68a16cd60c9b89edf2c. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. c5f72be0aa11e563c4fd7cbf1edd379a7df0cbbcd7ef264a525b9f3a335b62a2
2. 402156d424e4952569aa5fc72847fd893bd45816b9b5b797cba53f07a0620e4c
3. 50d1812f81dcf7b56ba84b1446608122273e91c2e32f42eb2ae738c1fb2193ee

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.