Password protected PDF using C#

Question

I am creating a pdf document using C# code in my process. I need to protect the docuemnt with some standard password like \"123456\" or some account number. I need to do th

Answer 1

If anyone is looking for a IText7 reference.

    private string password = "@d45235fewf";
    private const string pdfFile = @"C:\Temp\Old.pdf";
    private const string pdfFileOut = @"C:\Temp\New.pdf";

public void DecryptPdf()
{
        //Set reader properties and password
        ReaderProperties rp = new ReaderProperties();
        rp.SetPassword(new System.Text.UTF8Encoding().GetBytes(password));

        //Read the PDF and write to new pdf
        using (PdfReader reader = new PdfReader(pdfFile, rp))
        {
            reader.SetUnethicalReading(true);
            PdfDocument pdf = new PdfDocument(reader, new PdfWriter(pdfFileOut));
            pdf.GetFirstPage(); // Get at the very least the first page
        }               
}