For several years now, the PDF has become a benchmark, being a widely used file format both in the home and at work. When using these files, security can be a fundamental factor, especially if we work with confidential information. For this reason, it is normal to encrypt it with a password to protect it, but sometimes it is not enough, and it is possible that they require not only encryption, but also that it can only be opened from a single computer.
With a program of this type, we not only managed to protect our PDF, but also, in the event that someone could obtain a copy of the file, even decrypting the password, they would not be able to open it on another computer other than ours, so that we have an additional certainty that the information it contains will be safe.
Protecting a PDF with only a password is not as secure as it might seem, since it can be easily decrypted and shared. There are even a wide variety of free programs developed to remove passwords from PDFs, which would be able to remove their protection and restrictions without much effort.
PDF Secret, prevent the document from opening on another PC
This is a software developed to help owners of PDF files who want to restrict the distribution and opening of their documents by other users. To achieve this, we must generate a local key on the computer and then encrypt the file from the PC itself using the local key and this software.
This ensures that the encrypted PDF is created along with the decryption key. So, when trying to unlock it, it will be necessary to use the local key, so, if it is done from the same PC, we will be able to decrypt the file. However, it will not be possible to open the encrypted PDF on another device if the opening key is not verified; even though you have the decryption key.
Among the main features of PDF Secret we find the ability to generate local keys, generate owner keys, pair local and owner keys, lock the PDF on a specific computer and prevent unauthorized users from opening and distributing the files . Although it is an application that is no longer supported, it continues to work correctly. To begin, we must download its latest version available for free and install it.
How to use
Once installed, we run it and its main interface appears from where we can carry out the necessary operations. It is in English, but it is also very intuitive and easy to use. The first thing will be to generate a local key, for which we are going to click on its Get Local Key section.
This will make the program create it automatically and it will appear on the screen. Next, we copy it to the clipboard by clicking on the Copy the Key button.
Next we are going to encrypt the PDF for which we click on the Encrypt PDF button.
Pressing opens a window with the File Explorer, from where we will open the desired file, where we must copy the local key created previously and click on the Generate button. We choose the storage location and the program will inform us that the PDF has been created successfully along with its decryption key.
If we want to share the file with another user, we must send both the PDF and the TheKey.txt file. In order to open it, you will need to have Secret PDF and click on the Open PDF option.
Next, you will need to enter the encrypted PDF along with the decryption key sent. Once done, the PDF will open with the default reader.
In case the PC is not verified, the PDF will not be decrypted so it cannot be opened, so the security of its content will be safe.
PDF Unshare, prevent it from being viewed or edited without permission
This software has been designed to help us protect our PDF files, preventing them from being shared, edited, copied or accessed without authorization. This security tool creates PDF and UPDF formats that cannot be shared to protect our documents, since each protected PDF/UPDF file can only be opened from a computer or mobile device.
Among the main features of PDF Unshare we find:
- Allows you to set text and watermark color for PDF files.
- Set PDF expiration date.
- Avoid screenshots.
- Restrict access to PDF files on 1 device only.
- Compatible with 2 output formats: UPDF/ PDF.
To start using it, all you have to do is download PDF Unshare for free from its official website and install it on your computer. The free version is only for home use, for professional use it will be necessary to pay for its license, which costs 49 dollars. Although the application interface is in English, the process is quite simple, as we will see below.
How to protect PDFs
Once installed, we run the program and its main menu will appear. The first thing we will do is open the PDF file, for which we click on the Open button that we find on its toolbar or simply drag and drop the file on its interface.
Next, we are going to enable the protection options so that it can only be opened on one device, for which in the Limit the number of devices the file can be opened box, we mark 1 , so that it can only be opened on one device.
Later, we go on to establish the expiration date of the file, in the Expiration Date section. Once the current date exceeds the expiration date, the file can no longer be viewed or accessed. In addition, PDF Unshare takes care of verifying the date with the online server, so if the date and time of the device is changed, the verification cannot be skipped.
Now, we go on to save the document in PDF or UPDF format, for which we click on the Create UPDF or Create Unshared PDF button .
Finally, we review the file and send it to the person we want to be able to see the document, who will also have to install the application to be able to access the document . Once the unshared file is left on another computer, it cannot be opened again on another device, regardless of any attempts to copy or transfer the file, it will no longer be able to be opened on another device, displaying the message ” Opening the file on this device is not allowed”