How to decrypt a pdf file by supplying password of the file as argument using c#?

Question

I have generated a pdf file with password protection by using the following code:

using (Stream input = new FileStream(InputFile, FileMode.Open, FileAccess.Read, FileShare.Read))
{
    using (Stream output = new FileStream(OutputFile, FileMode.Create, FileAccess.Write, FileShare.None))
    {
        PdfReader reader = new PdfReader(input);
        PdfEncryptor.Encrypt(reader, output, true, strDob, "secret", PdfWriter.ALLOW_SCREENREADERS);
    }
}

I want to remove the password for the PDF file generated using the above code based on my certain condtions through code.

What library are you using to write the PDF? Does its manual mention anything about removing passwords from existing files? Isn't reading the password-protected file and writing the data in a new file without a password an option? — CodeCaster, Jun 13 '12 at 11:48
I have used itextsharp dll. and folowwing namespaces to generate password protected pdf file.using iTextSharp.text; using iTextSharp.text.pdf; — Harikasai, Jun 14 '12 at 05:34
possible duplicate of http://stackoverflow.com/a/10169551/298573 — VahidN, Jun 13 '12 at 18:55
Hi,Thanks for the response.I have referred the above link.but PdfReader.unethicalreading is not coming in my intelliscence. and i haven't used any AES or Rijndael algorithms for provindig pasword protection.I have tried with Rijndael Decrypt() method also.But didn't work out :( — Harikasai, Jun 14 '12 at 05:27
You need the latest version. unethicalreading is added recently. — VahidN, Jun 14 '12 at 09:48

score 3 · Accepted Answer · edited Mar 22 '13 at 15:13

string WorkingFolder = Environment.GetFolderPath(Environment.SpecialFolder.Desktop);
string InputFile = Path.Combine(WorkingFolder, "test.pdf");
string OutputFile = Path.Combine(WorkingFolder, "test_dec.pdf");//will be created automatically
//You must provide owner password but not the user password .
private void DecryptFile(string inputFile, string outputFile)
{

    string password = @"secret"; // Your Key Here           
    try
    {
        PdfReader reader = new PdfReader(inputFile, new System.Text.ASCIIEncoding().GetBytes(password));

            using (MemoryStream memoryStream = new MemoryStream())
            {
                PdfStamper stamper = new PdfStamper(reader, memoryStream);
                stamper.Close();
                reader.Close();
                File.WriteAllBytes(outputFile, memoryStream.ToArray());
            }

    }
    catch (Exception err)
    {
        Console.WriteLine(err.Message);
    }
}

//I got the solution finally :) ... Use the following code for removing password protection to a pdf file. //Nasmspaces using iTextSharp.text;// u must add itextsharp.dll as reference using iTextSharp.text.pdf; using System.IO; using System.Text; — Harikasai, Jun 14 '12 at 11:07

How to decrypt a pdf file by supplying password of the file as argument using c#?

1 Answers1

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