This app used to be $4.99 and then it shot up to $9.49 about a month ago. Noticed this app was on sale at $5.49 for another few days.
Link (Google Play Store)
Cryptomator makes your cloud storage trustworthy. The app encrypts files on your mobile device before they are uploaded to your cloud. Even if a third party gained unauthorized access to your files (e.g., hacker attack), your files are secure from prying eyes.
Cryptomator has been developed with a strong focus on user-friendliness.
• Simply create a vault and assign a password
• No additional account or configuration needed
• Unlock vaults with your fingerprint*
* from Android 6.0 and smartphones with fingerprint sensor
Cryptomator is compatible with the most commonly used cloud storages and available for all major operating systems.
• Compatible with Dropbox, Google Drive, OneDrive, and WebDAV-based cloud storage services
• Create vaults in Android's local storage (e.g., works with third-party sync apps)
• Access your vaults on all your mobile devices and computers
Cryptomator for Android is based on the solid open-source foundation of Cryptomator for Desktop.
• File content and filename encryption with AES and 256 bit key length
• Vault password is secured with scrypt for enhanced brute-force resistance
• Vaults are automatically locked after sending app to background
• Crypto implementation is based on the open-source library CryptoLib and is publicly documented
Cryptomator received the CeBIT Innovation Award 2016 for Usable Security and Privacy. We're proud to provide security and privacy for hundreds of thousands of Cryptomator users.