PyPDF 2 Decrypt Not Working

Question

Currently I am using the PyPDF 2 as a dependency.

I have encountered some encrypted files and handled them as you normally would (in the following code):

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Answer 1

It has nothing to do with whether the file has been decrypted or not when using the method getNumPages().

If we take a look at the source code of getNumPages():

def getNumPages(self):
    """
    Calculates the number of pages in this PDF file.

    :return: number of pages
    :rtype: int
    :raises PdfReadError: if file is encrypted and restrictions prevent
        this action.
    """

    # Flattened pages will not work on an Encrypted PDF;
    # the PDF file's page count is used in this case. Otherwise,
    # the original method (flattened page count) is used.
    if self.isEncrypted:
        try:
            self._override_encryption = True
            self.decrypt('')
            return self.trailer["/Root"]["/Pages"]["/Count"]
        except:
            raise utils.PdfReadError("File has not been decrypted")
        finally:
            self._override_encryption = False
    else:
        if self.flattenedPages == None:
            self._flatten()
        return len(self.flattenedPages)

we will notice that it is the self.isEncrypted property controlling the flow. And as we all know the isEncrypted property is read-only and not changeable even when the pdf is decrypted.

So, the easy way to handle the situation is just add the password as key-word argument with empty string as default value and pass your password when using the getNumPages() method and any other method build beyond it