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

1c5780b6fc45983276b7186eb6ac6268e637229b7baba42ddf184d6049257a28

Seed

0191c61a6f53a0d39e231173942718e448fd83fb3701967067074897b2aef25e SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

c03d26ae68808b03accaf1439d67aee4

Commitment

Batch 51,539, Merkle root d2c59aa8105d754ac86519c3fa14064f340a73e24dab0b6c3462d46e6b313127. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. eeadc6eabafbcc51bf165c71046e8dd32ad8a6b8c3958b551f70c446b466230b
2. 64f2539a7bfb4c82c6b1bddf31e523f3c16be89b2c63b82bab38f416f7327a64
3. 62d1cddd12522c47f3c11cf7142582cbcedb51bcbea6c8cffe1158227e6d0dfe
4. a183ec0b8f33482e19838c75abebbbb8c212701389d26c6545d1e05e395bb750

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.