How to add Digitally Sign to PDF File
In order to add sign in PDF file, we’ll use Aspose.PDF API which is a feature-rich, powerful and easy to use document manipulation API. Open NuGet package manager, search for Aspose.PDF and install. You may also use the following command from the Package Manager Console. When signing a PDF document using a signature, you basically confirm its contents “as is”. Consequently, any other changes made afterward invalidate the signature and thus, you would know if the document was altered.
You can use following classed and method for PDF signing
- Class DocMDPSignature.
- Enumeration DocMDPAccessPermissions.
- Property IsCertified in PdfFileSignature class.
Sign PDF with digital signatures.
This sample code shows how to sign PDF File
var esign_doc = new Document("My File.pdf");
var page = esign_doc.PdfDocument.Pages[1];
// Create text stamp
TextStamp textStamp = new TextStamp(getFormattedText("digital signature text"));
// Set whether stamp is background
// textStamp.Background = true;
textStamp.HorizontalAlignment = HorizontalAlignment.Right;
textStamp.VerticalAlignment = VerticalAlignment.Bottom;
textStamp.TextAlignment = HorizontalAlignment.Center;
textStamp.TextState.Font = FontRepository.FindFont("Arial");
textStamp.TextState.FontSize = 50;
textStamp.Width = page.PageInfo.Width / 3;
textStamp.TextState.ForegroundColor = Color.FromRgb(System.Drawing.Color.Aqua);
page.AddStamp(textStamp);
esign_doc.Save("esignedFile.pdf", SaveFormat.Pdf);
About Aspose.PDF API
Aspose.PDF API can be used for PDF document manipulation and parsing within applications. One can create, modify, compress, secure, print or save PDF to TXT, HTML, PCL, XFA, XML, XPS, EPUB, TEX, Images and more formats. Aspose.PDF is a standalone API and it does not depend on any software including Adobe Acrobat.