For security reasons, users like to encrypt their PDF files especially confidential data. They would set permission requirements or add passwords to restrict users’ activities such as to disallow printing, etc. However, sometimes due to certain reasons or special circumstances, we are empowered legally to crack password protected or encrypted PDF files. For instance, your boss requires you to print some documents but the documents are protected by a former colleague who has left the organization. Under this situation, you have no choice but to find a solution to unlock or crack the encrypted PDF files.
In most PDF encrypt tools or applications, users are normally allowed to apply two types of passwords: owner password and user password. With owner password, users will have full access to the PDF files without any restriction. Users will be controlled or restricted in certain actions such as viewing only but no printing if they were given a user password.
To open a password protected PDF file, you can try out a more commercial solution using password decryption tools. There are two applications you can actually try: –
Advanced PDF Password Recovery
Advanced PDF Password Recovery from ElcomSoft is a program to decrypt password-protected and restricted Adobe Acrobat PDF files which have either “owner password” or user password. This software uses methods like Brute Force, Mast, Key Search and Dictionary Attack to guess the password and remove the protection. It will try all the possible character combinations to decrypt the files. However, the process might be lengthy and time consuming. If you want to have a feel on how this software works, you can actually download the trial version via the link here. Of course, many functions have been disabled in the trial version.
PDF Password Remover
Another software you can try is PDF Password Remover by VeryPDF. This software can be used to decrypt protected Adobe Acrobat PDF files, which have “owner” password set, preventing the file from editing (changing), printing, selecting text and graphics (and copying them into the Clipboard), or adding/changing annotations and form fields. Decryption is done instantly. Decrypted file can be opened in any PDF viewer (e.g. Adobe Acrobat Reader) without any restrictions — i.e. with edit/copy/print functions enabled. All versions of Adobe Acrobat (including 7.x, which features 128-bit encryption) are supported. However, there is a limitation in this software. It doesn’t work with documents which have “user password”. You can also download the trial version of PDF Password Remover for testing.
PDF Unlocker is a freeware that able to remove PDF restrictions.