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

a68db8db67ef17b1f8689942798a3f83d298b9821c73f65661c0000603ad4967

Seed

8dc006b90f4c7f2e43aa1fa7d535df2210bea829358df36fecfbfa3cb4f497df SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

902bcef87cc0346aaef56cf9085bbfba

Commitment

Batch 69,589, Merkle root 7acbee9fa640667b13ceabace255c5049e31cfc788ac9dfb3445cec05585d05a. Recorded by Degen Protocol; on-chain publication is not available yet. See this batch and its Merkle tree

Merkle path

1. 0dac73b962d2415f29ab964f773736526f377c82190f6d5177ffb599d48de976
2. 3c58d9ac3f0f9e139fd53472d44e77fbf25ffa980a72ca927adfd33d9e8cba61
3. 8b8f5e268b9ee41c4bd7f286e46fceb6530369b8ff44de770ff22193c212528c

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.