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

07bbbc692b3a77be8de40772547ca0e55db38e42c0a521afa2bd01a3d4e728d5

Seed

5e1df9982b7f42bf6ee1122229cffff44c4be2102846d2665a20587dd7ddd19f SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

0487140eaffbb0549461ab220beb93fb

Commitment

Batch 72,127, Merkle root 2a8b74719f686a8cf88b2a549b6f49f857144956e8370f9e38c79c3a9b2fccd3. Recorded by Degen Protocol; on-chain publication is not available yet. See this batch and its Merkle tree

Merkle path

1. 22b72056473155b82952e07bdac36c6498754c01b73a0db5862fce43f49bb1bc
2. fc43f57da3a8d5c16b7531c7a1a23008cb6e53cc83bc723f02e50ff176a10b6c
3. cb00f135cd4201e92be07e357418efe6af5cf2936568e2e198f4953a5ffb781f

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.