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

58f7b85bd16853cc1229fb6014a9768bf46aa57fc93981a07e657d310f89327f

Seed

b46bdeaa319ef8310063d2ca46ffe078c6dde43ac1c1bf8676d9719738f01de8 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

4d770927257ae39daee8872803f62124

Commitment

Batch 72,245, Merkle root 02070a015b37cb286cc29eb76e20de899f0a62f0a25875462a8d865a25ef9e93. Recorded by Degen Protocol; on-chain publication is not available yet. See this batch and its Merkle tree

Merkle path

1. 6d53749d7d27d57e5d7ba7ab2b344dfe112711c042930b3913f5089ca7848d36
2. ab948c9456d70d99a6d061fb51cb3729020402f50db21884371df06d6ed5ce7a
3. db68111c73d59f1e7293ae1552d9b1cfe2787b23edb80deba34ff31902aab87c

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.