Assuming Kryptonite does back up data to iCloud, there are two things to note: 1. iCloud backups are encrypted. 2. If you're not comfortable with #1, you can

Assuming Kryptonite does back up data to iCloud, there are two things to note: 1. iCloud backups are encrypted. 2. If you're not comfortable with #1, you can manually exclude an individual app from iCloud backups through Settings > Storace & iCloud Usage > Manage Storage (in the iCloud section). Click on your device in the Backups section. Turn off Kryptonite in the "Choose Data to Back Up" section.