Any file can be password protected if you are using Linux, that is a good idea, in order to have them stored in the cloud, or carry them in a usb dongle.
To encrypt a file in Linux we will use, gpg which is parte of the GnuPG. Syntax of gpg
gpg -c filename.ext
Let's imagine we have a file called my-personal-info.txt
I want to encrypt with a password to protect the file, run this command.
gpg -c my-personal-info.txt
The output of the command is:
$ gpg -c my-personal-info.txt Enter passphrase:
Enter a good passphrase, be sure to remember it, and do not use an easy one.
Then you will get
Now gpg has created an encrypted file called my-personal-info.txt.gpg, the original file is still there, so you may want to erase it, or only transport the encrypted one, or send by email the encrypted one.
To decrypt a file just enter this command.
You will be asked for the password or passphrase, and the file will be recreated. This is a good idea to store some important information like passwords to important sites.