One of the key features of PDF format is the great security. There are basically two kinds of password, the owner password and user password. The authors can restrict readers from opening the PDF, that is the user password. Or he can set the owner password which can restrict others from copying, printing. They will well protect the copyright, readers can only deal with the PDF files within their authority.
*note:- Anyone crack the PDF formate....
However, PDF security also bothers many users. There must be someone who has the legal right to open an encrypted PDF documents, but forgot the password or some other reasons like in the situations below.
A publisher want to publish one of your novels you wrote many years ago, but you were kicking yourself saving it in PDF and protected it by owner password. No matter how hard you try but you just can not remember the password. You must remove the restrictions and get the precious chance.
Or you are authorized to check a bunch of critical PDF files, which were created and encrypted by a former department manager. You need to open these files and print them. Or this job will take you a month or longer.
In both cases, you have no option but to crack the PDF password. Do not panic, removing PDF password is not impossible.
When you can not copy and print the PDF files
There is a tips using Gmail to view protected PDF. Send the protect PDF to your Gmail then view as HTML. So you can copy and print the PDF in your browser. If the files are too large, this way is not going to work. And some PDF users reflect that this way will not work anymore since Google has closed the beta version.
Or you can just remove the owner password using PDF Password Remover, then you can batch remove the PDF restrictions. It can decrypt 200 PDF files at one time, or just right-click the PDF file, select Decrypt with PDF Password Remover from the shortcut menu, the restrictions will be removed in seconds.
When you can not open the PDF files
Cracking user password is very difficult and time consuming. There is some software called password recovery. The common methods are Brute Force, Key Search, they will try all the possible combinations, the cracking will take days or even longer. But it may work finally.