Verifiable draws, done right
You don't have to take our word for it. Every summon on Cartuna uses an auditable cryptographic system: the result is set before you play and can be checked by you afterwards. Not even we can change what's already been set.
In plain words
We commit first
Before any summon, we generate a secret key and publish a fingerprint of it (a code). That fingerprint proves the key already existed, without revealing it.
You're part of the result
The result is computed by combining our secret key with your key and your summon number. Since part of the formula is yours, we have no way to pick what comes out.
Then we reveal the key
When the secret key rotates, we reveal the old one. You check that the published fingerprint matches it and that every result matches the formula.
For those who want the technical details
- We generate a secret server seed and publish its commitment =
SHA-256(server seed)before any summon. - You have a client seed and a nonce, which increases with every summon.
- The result comes from
HMAC-SHA256(server seed, client seed:nonce), converted into a number between 0 and 1. - On key rotation, we reveal the old server seed. You verify that
SHA-256(server seed)equals the published commitment and that every result matches the HMAC.
Because the commitment is published first and the client seed is yours, neither party can manipulate the result without being detected.
The current commitment is visible right on the summon page, before you play.
We only draw what we have in stock
The summoner only considers cards physically available in our stock. If a rarity runs out, it leaves the draw and the odds of the others are recalculated. This guarantees every summoned card really exists and can be shipped to you.
This isn't gambling
Every summon delivers a real, physical collectible card. There's no wager, no cash prize, and no way to end up with nothing. The verifiable system exists to prove the card you received was decided fairly.