Basically, files are encrypted using AES and RSA.
It involves 3 keys:
  1. Master key - 512-bit, derived from user inputted password, removed from memory as soon as not used
  2. RSA key pairs - 2048-bit, randomly generated for each protected folder
  3. Content key - 256-bit, randomly generated for each file
When a folder is added to be monitored, password is provided by user, and:
  1. Master key is being derived from the password
  2. RSA key pairs are generated randomly
  3. Private key of the key pairs is being encrypted with Master key, with AES-SIV
  4. The encrypted private key and public key of the key pairs are stored on the device
When a new file is being encrypted:
  1. Content key is randomly generated
  2. File content is encrypted by content key, with AES-GCM
  3. Content key is encrypted with public key of the folder, with RSA
  4. The resulting encrypted file contains the encrypted private key, encrypted content key, and the encrypted file content
Network access is used for synchronization of encrypted files with cloud storages, and for serving ads.
If upgraded to premium, as no ad would be served, the only network access would be for syncing files.
No. There is no method to restore the password as it is not even stored on disk (Please refer to our FAQ on protocol used). Also we have NO backdoor or special key which can decrypt the encrypted files.
SD cards are usually used as secondary storage on recent Android devices, you can configure Fileseal to encrypt secondary storage depending on your Android Version:
  • Android 4.1, 4.2, 4.3 - simply select the path of the secondary storage and it should work;
  • Android 4.4 - from 4.4 onwards, secondary storage is read only and there is no alternative method to acquire write access on it normally, therefore we do not support encryption on SD card on Android 4.4;
  • Android 5.0+ - starting from 5.0, Android introduced Document Provider Tree, Fileseal provides encryption on secondary storage through this feature.
In addition to the requirement above, Fileseal only provides encryption on secondary storage on Premium version.
Follow the following steps:
  1. Start add protected folder by pressing the add button
  2. Select "Use Document Provider" from the menu
  3. (optional)Select "Show SD cards" from the menu if you haven't done so
  4. Choose the SD card and go to the folder you want to encrypt
  5. Press the button "Select this folder" on the bottom of the screen
  6. Follow the remaining steps just as if you are encrypting a normal folder