Coolmuster PDF Locker

Locking a PDF file with a password is a valid option if you want to secure it. Especially if it's a sensitive document, encrypting it is really the best course of action to ensure that only those with the password can see it.

For more configurability, a third-party PDF encryption tool might prove useful. Coolmuster PDF Locker is a simple enough piece of software that anyone can use to secure their documents: encrypt them with a password, select your preferred encryption level, and toggle permissions as you see fit.

Perhaps the main draw of the software lies in its ability to encrypt multiple PDFs at once. This is good for efficiency, as you won't have to manually go through each one to configure their encryption. Though, it's still questionable if encrypting multiple documents with the same password is a good idea.

Either way, users should be able to add their documents without any issues. Interestingly enough, drag & drop did not work for us, so we had to locate them through the program instead. It was then time to configure our encryption settings with the options at our disposal.

Users can set two passwords: one to open the PDF file, and another to enable changing permissions. Most users should be fine with just locking others from opening the file, but it's nevertheless worth considering to block access to permissions if it's really something important.

There are also three different encryption levels to choose from: 128 bits AES, as well as RC4 on 128 or 40 bits, with each being suitable for certain Acrobat versions.

You may also toggle permissions to your liking. Choose whether to permit copying and modifying a document's contents, restrict or enable printing, form filling, and more.

Coolmuster PDF Locker is quite usable, but Free users should note that they can secure their documents no more than 3 times. In any case, the tool should do well enough for those seeking to simply lock a few documents here and there.