It may happen that we assign a password to a pdf file and over time we forget it, or at another extreme, people who do work for an institution and deliver it with a password that is ultimately lost. Although we pay for work and not for the password, losing it becomes almost like losing everything if we can not locate who did the work, much less if it was many years ago and you forgot that at that time you used the second name of girlfriend.
This time I will show two forms, although there are some that do it in line with which I have had very few good experiences.
1. Using PDF Password Remover
PDF Password Remover v3.1 is an application that for almost 30 dollars solves almost what we require. The trial version lets us work a limited amount of files, then asks us to buy the license, but to download it you have to deactivate the antivirus because if we have a very clever one, it will consider the site as offensive because the executable is directly.
What this program does is open the file, delete the password and ask us to record it elsewhere without protection. The disadvantage of this program is that it can decrypt a password of type "owner", However there is another type"user"that this version can not do it, as XueHeng told us, they hope to put this functionality in the next Pro version.
In case the file has a password of type user, input will ask us and if we do not know it raises the message:
"Password is not correct".
2 Using Crackpdf
This is a Linux application whose distribution can be downloaded from this site:
There are those who have readapted it for Windows, with the library cygwin1.dll that does not come in the original version and can be downloaded from this address
The file is decompressed, and since it has to be executed from a command line it is convenient to place it near the root directory. In this case I have saved the folder with the name "Pdff", I have also saved the protected file in the same folder with the name Sample.pdf. To run it we go to the DOS command console and remember some of the old commands that we learned earlier:
- This is done in Windows: Start> Run> cmd. When doing enter, we should see the black background console.
Now, we turn to the directory of our interest:
- No matter where we are, we must write: cd .. Then we do enter. We do it so many times until we have the root directory C: \>
- To enter the directory of our interest, we write: Cd pdff. With this the console should remain: C: \ dff>
- Now, we execute the command: Pdfcrack -f sample.pdf. This will cause the process to start a search cycle of possible keys, similar to what we see in the image. Depending on the complexity of the key, the search may take several hours, the action can be left running -Could be all night- until finally we will see a message like the one seen at the bottom: Found user-password: 'key that we are looking for'.
The routine looks simple, although it has more options, such as:
-w with which you can be given a list of possible keys from a file
-u so I only look for the user password, this is the default, so I did not need to type it
-o to search for owner password
-m to stop when it reaches a certain number of characters
-n so you do not search for words with a minimum of characters