Digital Signatures


Digital Signatures

Digital signatures can be added to a PDF document using PdfDigitalSignatureElement objects. Adding a digital signature requires a PKCS#12 certificate (provided as a .pfx or a .p12 file).

Sample Code

The following sample code shows how to add a digital signature to a pdf document using Select.Pdf Library for .NET.

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// create a new pdf document
PdfDocument doc = new PdfDocument();

// add a new page to the document
PdfPage page = doc.AddPage();

// get image path 
// the image will be used to display the digital signature over it
string imgFile = Server.MapPath("~/files/logo.png");

// get certificate path
string certFile = Server.MapPath("~/files/selectpdf.pfx");

// define a rendering result object
PdfRenderingResult result;

// create image element from file path 
PdfImageElement img = new PdfImageElement(0, 0, imgFile);
result = page.Add(img);

// get the #PKCS12 certificate from file
PdfDigitalCertificatesCollection certificates = 
    PdfDigitalCertificatesStore.GetCertificates(certFile, "selectpdf");
PdfDigitalCertificate certificate = certificates[0];

// create the digital signature object
PdfDigitalSignatureElement signature = 
    new PdfDigitalSignatureElement(result.PdfPageLastRectangle, certificate);
signature.Reason = "SelectPdf";
signature.ContactInfo = "SelectPdf";
signature.Location = "SelectPdf";
page.Add(signature);

// save pdf document
doc.Save(Response, false, "Sample.pdf");

// close pdf document
doc.Close();

' create a new pdf document
Dim doc As New PdfDocument()

' add a new page to the document
Dim page As PdfPage = doc.AddPage()

' get image path 
' the image will be used to display the digital signature over it
Dim imgFile As String = Server.MapPath("~/files/logo.png")

' get certificate path
Dim certFile As String = Server.MapPath("~/files/selectpdf.pfx")

' define a rendering result object
Dim result As PdfRenderingResult

' create image element from file path 
Dim img As New PdfImageElement(0, 0, imgFile)
result = page.Add(img)

' get the #PKCS12 certificate from file
Dim certificates As PdfDigitalCertificatesCollection = _
    PdfDigitalCertificatesStore.GetCertificates(certFile, "selectpdf")
Dim certificate As PdfDigitalCertificate = certificates(0)

' create the digital signature object
Dim signature As New PdfDigitalSignatureElement( _
    result.PdfPageLastRectangle, certificate)
signature.Reason = "SelectPdf"
signature.ContactInfo = "SelectPdf"
signature.Location = "SelectPdf"
page.Add(signature)

' save pdf document
doc.Save(Response, False, "Sample.pdf")

' close pdf document
doc.Close()

Reference

PdfDigitalSignatureElement