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

cb0dec73bf16f9d6cc54c57b40aafab8eeda872b14c8941de874478155e7953e

Seed

f1e31928ddabe10952524d13a068e4f6be9b3f26204c9d23b3f0d5fbdce61e79 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

e0299153c4f2d1b4983b528675a2e888

Commitment

Batch 50,906, Merkle root f4b0005de433eccf398091f5f3ebba710b0d6789af99638689f365f33d71e10f. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. d9aad98ff3104962d2b178afc1ba3616fd03720ad8c880ee7d68c4045ba199b8
2. d8bb67cdb2c564e1bf4a314283615f586316f171254cf7acebdab5b89197d0e0

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.