GroupDocs.Signature provides PdfMetadataSignature class to specify different Metadata signature objects for MetadataSignOptions instance.
PDF document metadata is hidden attributes, some of them are visible only over viewing standard document properties like Author, Creation Date, Producer, Entry, Keywords etc. PDF document metadata contains 3 fields: Name, Value and TagPrefix, combination of Name and Tag prefix should be unique.
PDF document metadata could keep big amount of data that provides ability to keep serialized custom objects with additional encryption in there. See Advanced examples how to embed secure data.
Here are the steps to add metadata signatures into PDF document with GroupDocs.Signature:
Create new instance of Signature class and pass source document path as a constructor parameter.
This example shows how to sign PDF document with several e-signatures as metadata.
using(Signaturesignature=newSignature("sample.pdf")){MetadataSignOptionsoptions=newMetadataSignOptions();options.Add(newPdfMetadataSignature("Author","Mr.Scherlock Holmes"))// String value.Add(newPdfMetadataSignature("CreatedOn",DateTime.Now))// DateTime values.Add(newPdfMetadataSignature("DocumentId",123456))// Integer value.Add(newPdfMetadataSignature("SignatureId",123.456D))// Double value.Add(newPdfMetadataSignature("Amount",123.456M))// Decimal value.Add(newPdfMetadataSignature("Total",123.456F));// Float value// add these signatures to optionsoptions.Signatures.AddRange(signatures);signature.Sign("SampleSigned.pdf",options);}
How to eSign PDF with standard metadata signatures
This example shows how to sign PDF document with standard standard embedded PDF document metadata signatures. If PDF metadata signature already exists with same name its value will be overwritten.
using(Signaturesignature=newSignature("sample.pdf")){MetadataSignOptionsoptions=newMetadataSignOptions();// Using standard Pdf Metadata Signatures with new valuesMetadataSignature[]signatures=newMetadataSignature[]{PdfMetadataSignatures.Author.Clone("Mr.Scherlock Holmes"),PdfMetadataSignatures.CreateDate.Clone(DateTime.Now.AddDays(-1)),PdfMetadataSignatures.MetadataDate.Clone(DateTime.Now.AddDays(-2)),PdfMetadataSignatures.CreatorTool.Clone("GD.Signature-Test"),PdfMetadataSignatures.ModifyDate.Clone(DateTime.Now.AddDays(-13)),PdfMetadataSignatures.Producer.Clone("GroupDocs-Producer"),PdfMetadataSignatures.Entry.Clone("Signature"),PdfMetadataSignatures.Keywords.Clone("GroupDocs, Signature, Metadata, Creation Tool"),PdfMetadataSignatures.Title.Clone("Metadata Example"),PdfMetadataSignatures.Subject.Clone("Metadata Test Example"),PdfMetadataSignatures.Description.Clone("Metadata Test example description"),PdfMetadataSignatures.Creator.Clone("GroupDocs.Signature"),};options.Signatures.AddRange(signatures);// sign document to filesignature.Sign("sample_signed.pdf",options);}
Advanced Usage Topics
To learn more about document eSign features, please refer to the advanced usage section.
More resources
GitHub Examples
You may easily run the code above and see the feature in action in our GitHub examples: