PDF files are widely used for sharing documents across different platforms, but they also pose a security risk if sensitive information is included in the file. Adding a password to a PDF file can help ensure that only authorized individuals can access its contents. On the other hand, removing a password from a PDF file can make it easier to share with others who may not have the password. In this article, we will discuss how to add and remove passwords from PDF files on Linux.

Adding a Password to a PDF File on Linux:

To add a password to a PDF file on Linux, you can use the qpdf tool, which is a command-line program that allows you to manipulate PDF files. To install qpdf on Ubuntu or Debian-based systems, you can use the following command:

sudo apt-get install qpdf

Once qpdf is installed, you can use the following command to add a password to a PDF file:

qpdf --encrypt <user_password> <owner_password> <permissions> -- <input.pdf> <output.pdf>

Replace <user_password> and <owner_password> with the passwords you want to set for the PDF file. The <permissions> parameter specifies the permissions that users will have when accessing the file. For example, you can use print, modify, copy, and annot-forms. The <input.pdf> parameter specifies the input PDF file that you want to encrypt, and the <output.pdf> parameter specifies the output PDF file with the added password.

Removing a Password from a PDF File on Linux:

To remove a password from a PDF file on Linux, you can use the qpdf tool as well. If you know the password of the PDF file, you can use the following command:

qpdf --password=<password> --decrypt <input.pdf> <output.pdf>

Replace <password> with the password of the PDF file, <input.pdf> with the input PDF file that you want to decrypt, and <output.pdf> with the output PDF file without the password.

If you do not know the password of the PDF file, you can try to remove the password using the pdfcrack tool, which is a PDF password cracker. To install pdfcrack on Ubuntu or Debian-based systems, you can use the following command:

sudo apt-get install pdfcrack

Once pdfcrack is installed, you can use the following command to remove the password from a PDF file:

pdfcrack -o <output.pdf> <input.pdf>

Replace <output.pdf> with the output PDF file without the password and <input.pdf> with the input PDF file that you want to crack the password.

In conclusion, adding and removing passwords from PDF files on Linux can be done easily using tools such as qpdf and pdfcrack. By following the steps outlined in this article, you can ensure the security of your PDF files while also allowing easy access for authorized users.