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

0c8712cd2c79d7a57e4475cdc63cc512a0851c92d936172fe3cd891869da3277

Seed

ef571add125f5e9a0b5dc4f29672c72f59667a9ab3c52e4ab8a0c9be6daf157d SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

e97c96a33b5b47c61abf12d6332d3972

Commitment

Batch 49,464, Merkle root 95e34f9d4b509b4a2c4a298d19aa74845bd5a2a5e5ee91ea3a7ddb938ef29e60. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. bd67699b8332397901e0d28a06202385ef6127509f0f66625fc5ac5a75d472f9
2. 96015f7c56c73989dfc2d3d3ee662c562c24c8161480346b3c73298462a010ae
3. a4de3a58d8bda2e78903162d5678385c6bc0eee6ba93aaa64f63b1df48170244

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.