.NET Digital Signature Library

Electronically Sign Documents from a wide range of file formats. Supports several types of e-signing methods.

e-Sign Documents in .NET Apps

Create and add signatures to documents of various file formats.
Specify visual attributes of signatures, such as color, font, margins, etc.
Search and fetch a list of signatures from a document.
Determine if the document contains signatures meeting specified criteria.
Extract basic information about the document.
Generate image representation of document pages for preview.
Distinguish created signatures from the actual document.
Put encrypted text into the QR-code signature or embed custom data objects.

New Features & Enhancements v20.11

Implemented the additional customization of PDF Digital Signature appearance.
Improved the save feature of Open Office documents with the OTT file format.
Implemented support of Native Text Signature implementation on the Image documents.
The Class PdfDigitalSignature has been updated as the Authority property has been removed.

Please visit GroupDocs.Signature for .NET 20.11 Release Notes for the detailed notes.

Signature Supported Formats

The following section lists the supported file formats for the barcode, image, QR-code, stamp, and text signature types: Microsoft Word: DOC, DOCM, DOCX, DOT, DOTM, DOTX
Microsoft Excel: XLSX, XLS, XLSB, XLSM, XLTX, XLTM
Microsoft PowerPoint: PPTX, PPTM, PPT, PPSX, PPSM, PPS, POTX, POTM
OpenOffice: ODT, OTT, ODS, OTS, ODP, OTP
Image: BMP, GIF, JPG, JPEG, PNG, SVG, TIF, TIFF, WEBP
CorelDraw: CDR, CMX
Photoshop: PSD
Metafile: WMF
Portable: PDF

Digital Signature Supported Formats

Microsoft Word: DOC, DOCM, DOCX, DOT, DOTM, DOTX
Microsoft Excel: XLSX, XLS, XLSB, XLSM, XLTX, XLTM
OpenOffice: ODS, OTS
Portable: PDF

FormField Signature Supported Formats

Microsoft Word: DOC, DOCM, DOCX, DOT, DOTM, DOTX
Microsoft Excel: XLSX, XLS, XLSB, XLSM, XLTX, XLTM
OpenOffice: ODS, OTS, ODP
Portable: PDF

Metadata Signature Supported Formats

Microsoft Word: DOC, DOCM, DOCX, DOT, DOTM, DOTX
Microsoft Excel: XLSX, XLS, XLSB, XLSM, XLTX, XLTM
Microsoft PowerPoint: PPTX, PPTM, PPT, PPSX, PPSM, PPS, POTX, POTM
OpenOffice: ODT, OTT, ODS, OTS, ODP, OTP
Image: JPG, JPEG, PNG, SVG, TIF, TIFF
Photoshop: PSD
Portable: PDF

Supported Signature Types

Text stamps
Text labels
Text as an image signature
Image signature
Digital signature
Barcode signature
QR-code signature
Metadata signature
Form-field signature

Platform Independence

GroupDocs.Signature for .NET does not require any external software or third party tool to be installed. GroupDocs.Signature for .NET supports any 32-bit or 64-bit operating system where .NET or Mono framework is installed. The other details are as follows:

Microsoft Windows: Microsoft Windows Desktop (x86, x64) (XP & up), Microsoft Windows Server (x86, x64) (2000 & up), Windows Azure
macOS: Mac OS X
Linux: Linux (Ubuntu, OpenSUSE, CentOS and others)
Development Environments: Microsoft Visual Studio (2010 & up), Xamarin.Android, Xamarin.IOS, Xamarin.Mac, MonoDevelop 2.4 and later.
Supported Frameworks: GroupDocs.Conversion for .NET supports .NET and Mono frameworks.

Sign a PDF File and Save it in DOCX Format using C# Code

using (Signature signature = new Signature("sample.pdf"))
{
    // create QRCode option with predefined QRCode text
    QRCodeSignOptions signOptions = new QRCodeSignOptions("JohnSmith")
    {
        EncodeType = QRCodeTypes.QR,
        Left = 100,
        Top = 100
    };
    PdfSaveOptions pdfSaveOptions = new PdfSaveOptions()
    {
        FileFormat = PdfSaveFileFormat.DocX,
        OverwriteExistingFiles = true
    };
    // sign document to file
    signature.Sign("SignedPdf.docx", signOptions, pdfSaveOptions);
}

Use C# to Search and Delete Signatures from DOCX File

// initialize Signature instance
using (Signature signature = new Signature("signed.docx"))
{
    BarcodeSearchOptions options = new BarcodeSearchOptions();
    List<BarcodeSignature> signatures = signature.Search<BarcodeSignature>(options);
    List<BaseSignature> signaturesToDelete = new List<BaseSignature>();
    // collect signatures to delete
    foreach (BarcodeSignature temp in signatures)
    {
        if (temp.Text.Contains("John"))
        {
            signaturesToDelete.Add(temp);
        }
    }
    // delete signatures
    DeleteResult deleteResult = signature.Delete(signaturesToDelete);
    if (deleteResult.Succeeded.Count == signaturesToDelete.Count)
    {
        Console.WriteLine("All signatures were successfully deleted!");
    }
    else
    {
        Console.WriteLine($"Successfully deleted signatures : {deleteResult.Succeeded.Count}");
        Console.WriteLine($"Not deleted signatures : {deleteResult.Failed.Count}");
    }
    Console.WriteLine("List of deleted signatures:");
    foreach (BaseSignature temp in deleteResult.Succeeded)
    {
        Console.WriteLine($"Signature# Id:{temp.SignatureId}, Location: {temp.Left}x{temp.Top}. Size: {temp.Width}x{temp.Height}");
    }
}