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

c6445e50eddfcd4d3167253e72cd81f938d76e98039ced58c64196be291293c2

Seed

f2d6db935a4b6c2fe33650888235eb1767ae1a1bc124e3f1decdbb7c6e7d0a34 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

a1935861b9639ea57113ccf0e7eb9970

Commitment

Batch 64,865, Merkle root 9d51ad17e62f7a2b2de8d5fb12e1e55b01774f6dadeb9da3192f4bc85f1f63ab. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 097735b220dd96ad1e09b43d9c8eafeaf0c78a771c49091a698447b571eea9e0
2. 300524584f660793d86472b165089af3cf17f49a757fbe914dda357b0b2faf45

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.