Generate digital signature in PDF and verify the certificate

Question

Hi friends! How to generate digital signature in PDF and verify the certificate using private and public key authentication,I am tried 3 days two many ways but not clear explanation,if you know share me. Hopefully SavadaMuthu Saravanan

Mohamed Abedallah · Answer

You can use LEADTOOLS to both 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/v19/dh/pdf/pdfsignature.html

Leon D · Answer

Generate and verify digital signature is straightforward with Spire.PDF library. You can reference its free version (free spire.pdf dll) from NuGet Package Manager and have a try. The following guidance might be of help to you: https://www.e-iceblue.com/Tutorials/Spire.PDF/Spire.PDF-Program-Guide/PDF-Security/Create-Visible-Digital-Signature-in-PDF-with-C-Code.html https://www.e-iceblue.com/Tutorials/Spire.PDF/Spire.PDF-Program-Guide/Get-and-Verify-Digital-Signature-in-PDF-with-C-Code.html

Savadamuthu Saravanan · Answer

How add a self-signed question mark in digital signature using spire dll

Savadamuthu Saravanan · Answer

Hi sir, Ths line PdfSignature signature = new PdfSignature(doc, page, digi, "demo"); doc,page run time type error will diplay In this line signature.Certificated = true; Out of range error display. If you know give me the solution. Thank you & Regards S.Savadamuthu.