checking if pdf is password protected using itextsharp

Question

I want to check if a pdf file is password protected or not to view. That is i want to know if the pdf file has user password or not.

I found some help in some forum about it to use isencrypted function but it does not give correct answer.

Is it possible to check if a pdf is password protected?

Answer 1

The problem with using the PdfReader.IsEncrypted method is that if you attempt to instantiate a PdfReader on a PDF that requires a password - and you don't supply that password - you'll get a BadPasswordException.

Keeping this in mind you can write a method like this:

public static bool IsPasswordProtected(string pdfFullname) {
    try {
        PdfReader pdfReader = new PdfReader(pdfFullname);
        return false;
    } catch (BadPasswordException) {
        return true;
    }
}

Note that if you supply an invalid password you'll get the same BadPasswordException when attempting to construct a PdfReader object. You can use this to create a method that validates a PDF's password:

public static bool IsPasswordValid(string pdfFullname, byte[] password) {
    try {
        PdfReader pdfReader = new PdfReader(pdfFullname, password);
        return false;
    } catch (BadPasswordException) {
        return true;
    }
}

Sure it's ugly but as far as I know this is the only way to check if a PDF is password protected. Hopefully someone will suggest a better solution.