Digital signatures in pdf file

Pankaj Rana

14y7.8k.NET

hi
how to add digital signatures in pdf file in c#

6 Replies

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Atir Tahir6y ago
Use GroupDocs.Signature for .NET in order to sign a PDF document programmatically.
using (Signature signature = new Signature("sample.pdf"))
{
    // initialize digital option with certificate file path
    DigitalSignOptions options = new DigitalSignOptions("certificate.pfx")
    {
        // optional: setup image file path
        ImageFilePath = "sample.jpg",

        // set signature position
        Left = 100,
        Top = 100,

        // set
        Password = "1234567890"
    };
    signature.Sign("sampleSigned.pdf", options);
}
In case of any issue, raise it on free support forum https://forum.groupdocs.com/
+2
Bharat Vasant7y ago
If you are looking for Digitally Signing PDF file from Web Application (ASP.NET Application) using USB Token connected to client's device through web browser, here is the complete source code of the VS 2015 or VS 2017 project.

http://help.signer.digital/digital_signing_and_authentication_from_web_browser.htm

Free Online PDF Signing Software is at https://web.signer.digital
+6
Chittaranjan Swain7y ago
Hi pankaj,

Refer below links,
https://www.gemboxsoftware.com/pdf/examples/c-sharp-vb-net-pdf-digital-signature/1102
https://www.codeproject.com/Questions/318495/Digital-Signatures-and-PDF-Documents-csharp
https://www.sautinsoft.com/products/document/examples/digital-signature-net-csharp-vb.php
+1
Mohamed Abedallah7y ago
You can use LEADTOOLS to sign a PDF document using a certificate, and also verify an existing signature in a PDF file.

To sign a file, you can use the PDFFile.SignDocument method. The code looks like this:
PDFFile document = new PDFFile(sourceFileName);
document.SignDocument( destinationFileName, signatureFileName, signaturePassword);
Note that the “signatureFileName” is the file containing the digital signature. This should be a valid PFX file and cannot be null.

To check if there's a signature in an existing PDF file, the code will be similar to this:
private static bool ContainsSignature(string pdfFileName)
   {
     PDFDocument document = new PDFDocument(pdfFileName);
    PDFParsePagesOptions options = PDFParsePagesOptions.Signatures;
     document.ParsePages(options, 1, -1);

     foreach (PDFDocumentPage page in document.Pages)
     {
        IList objects = page.Objects;
        if (objects != null)
           return true;
     }
     return false;
   }
To verify a signature and see if it's valid, there are details in this help topic:
https://www.leadtools.com/help/leadtools/v20/dh/pdf/pdfsignature.html
+1
Gajendra Jangid7y ago
hello pankaj,

Please have a look at below link:

https://www.codeproject.com/Articles/14488/E-signing-PDF-documents-with-iTextSharp
+2
Leon D7y ago
You can use Spire.PDF to add digital signature to pdf in C#.
1. Install Spire.PDF from NuGet:
https://www.nuget.org/packages/Spire.PDF/

2. Use code like below:
PdfDocument doc = new PdfDocument(@"..\..\test.pdf");

PdfCertificate cert = new PdfCertificate(@"..\..\Demo.pfx", "e-iceblue");

var signature = new PdfSignature(doc, doc.Pages[0], cert, "Requestd1");

signature.Bounds = new RectangleF(new PointF(280, 600), new SizeF(260, 90));
signature.IsTag = true;
signature.DigitalSignerLable= "Digitally signed by";
signature.DigitalSigner = "Harry Hu for Test";
signature.DistinguishedName = "DN:";
signature.LocationInfoLabel = "Location:";
signature.LocationInfo = "London";
signature.ReasonLabel = "Reason: ";
signature.Reason = "Le document est certifie";
signature.DateLabel = "Date: ";
signature.Date = DateTime.Now;
signature.ContactInfoLabel = "Contact: ";
signature.ContactInfo = "123456789";
signature.Certificated = false;
signature.ConfigGraphicType = ConfiguerGraphicType.Picture;
signature.ConfiguerGraphicPath = "..\\..\\img1.png";
signature.DocumentPermissions = PdfCertificationFlags.ForbidChanges;

doc.SaveToFile("sample.pdf");
For more information, visit this link:
https://www.e-iceblue.com/Tutorials/Spire.PDF/Spire.PDF-Program-Guide/PDF-Security/Create-Visible-Digital-Signature-in-PDF-with-C-Code.html
+1