iOS doesn’t offer us a native way to protect our PDF files on iPhone or iPad. Luckily there are some third-party PDF apps and file manager apps can help us with that. FileMaster is a free file manager for iOS that can help us zip files with password. Documents app can even directly encrypt PDF files without the need to zip or compress them first.
Download the free Documents app here, then follow below steps to encrypt PDF files with password on your iPhone or iPad.
Add password to PDF
Open Files app, PDF or other file manager app where the PDF file is saved, select the PDF file you want to add password to. Tap on the action menu, choose Open in Documents from the menu list. You will then see a screen like this.
Once the PDF file opens in Documents app, tap on the Menu button (three dots) at the top right corner to bring up menu at the lower section of your iPhone screen. Choose Set Password. Then type in the same password twice. Finally hit the Set button to confirm and encrypt your PDF file on iPhone or iPad.
Now when anyone go to open the PDF file again, he or she will be prompted to unlock it with the password. Without the correct password, no one can open the PDF file.
Remove PDF password
The file manager app can also help users remove password from PDF files. If you decide to delete the password later, you can refer to this tutorial to remove password from PDF files on iPhone iPad.