CODEWITHSUNDEEP
c#asp.netpdfitext
Giri
Giri

Reputation: 941

how to password protect the digitally signed pdf?

I m creating and signing pdf using c#,itextsharp.Now i m using this code for password protection.

Can someone tellme why is this happening?

Thanks..

string passprotectedfile = filename;

using (Stream input = new FileStream(signedfile, FileMode.Open, FileAccess.Read,
                                     FileShare.Read))
{
    using (Stream output = new FileStream(passprotectedfile, FileMode.Create, 
                                          FileAccess.Write, FileShare.None))
    {
        PdfReader reader = new PdfReader(input);
        PdfEncryptor.Encrypt(reader, output, true, regno.ToString(), "",
                             PdfWriter.ALLOW_SCREENREADERS);
    }
}

Upvotes: 0

Views: 6515

Answers (2)

Darin Dimitrov
Darin Dimitrov

Reputation: 1038800

The whole point of a digital signature is to ensure that nobody has tampered with the contents of the file. By adding a password you are modifying it so the digital signature that was applied is no longer valid and this is what the error message is telling you. You will need to resign the PDF file after modifying it.

Upvotes: 4

unknown
unknown

Reputation: 1

private void Generatedigitalsignatureandpassprotected(string filepath, string filepass)
    {
        Document _document = new Document();

        _document.Title = "PdfDigitalSignature - Sample";
        _document.Author = "dbAutoTrack Ltd, USA";
        _document.Creator = "dbAutoTrack.PDFWriter";
        PDFDigitalSignature digitalSignature = new PDFDigitalSignature();
        //  digitalSignature.X509Certificate = new X509Certificate2(MapPath("../data/DigitalSignature.pfx"), "password", X509KeyStorageFlags.MachineKeySet |X509KeyStorageFlags.PersistKeySet | X509KeyStorageFlags.Exportable););
        string executingFolder = System.IO.Path.GetDirectoryName(Application.ExecutablePath);
        var digitalsignaturefilepath = "E:\\wwwroot\\NaveenWindowsAppFile\\WindowsFormsApplication1\\digitalsignaturefile\\DigitalSignature.pfx";
        digitalSignature.X509Certificate = new X509Certificate2(digitalsignaturefilepath, "password", X509KeyStorageFlags.MachineKeySet | X509KeyStorageFlags.PersistKeySet | X509KeyStorageFlags.Exportable);
        digitalSignature.Date = DateTime.Now;
        digitalSignature.Location = "Location ";
        digitalSignature.Reason = "Reason ";
        digitalSignature.ContactInfo = "Convert Digital Code by Cstech";
        digitalSignature.DetachSignature = false;
        digitalSignature.RootTrusted = false;
        _document.DigitalSignature = digitalSignature;
        //password protection code//
        SecurityManager _securityManager = new SecurityManager();
        _securityManager.Encryption = Encryption.Use128BitKey;
        _securityManager.OwnerPassword = filepass;
        _securityManager.UserPassword = filepass;
        _securityManager.AllowCopy = true;
        _securityManager.AllowEdit = true;
        //end//
        //Assign SecurityManager to the Document.
        _document.SecurityManager = _securityManager;
        PDFFont _font1 = new PDFFont(StandardFonts.TimesRoman, FontStyle.Regular);
        dbAutoTrack.PDFWriter.Page page1 = new dbAutoTrack.PDFWriter.Page(PageSize.A4);
        PDFGraphics graphics1 = page1.Graphics;

        PdfSignatureField signatureField = graphics1.AddDigitalSignature("name", new RectangleF(50, 50, 150, 75), _font1, 8f);
        signatureField.DigitalSignature = digitalSignature;
        _document.Pages.Add(page1);

        using (FileStream outFile = new FileStream(filepath, FileMode.Create, FileAccess.ReadWrite))
        {
            _document.Generate(outFile);
        }
    }

Upvotes: 0

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