/// <summary>
/// Signs the given <paramref name="openXmlPackage"/>, using the given
/// <paramref name="certificate"/>.
/// </summary>
/// <param name="openXmlPackage">The <see cref="OpenXmlPackage"/>.</param>
/// <param name="certificate">The <see cref="X509Certificate2"/>.</param>
public static void Sign(OpenXmlPackage openXmlPackage, X509Certificate2 certificate)
{
if (openXmlPackage == null)
{
throw new ArgumentNullException(nameof(openXmlPackage));
}
if (certificate == null)
{
throw new ArgumentNullException(nameof(certificate));
}
RSA privateKey = certificate.GetRSAPrivateKey();
using SHA256 hashAlgorithm = SHA256.Create();
// Create KeyInfo.
var keyInfo = new KeyInfo();
keyInfo.AddClause(new KeyInfoX509Data(certificate));
// Create a Signature XmlElement.
var signedXml = new SignedXml {
SigningKey = privateKey, KeyInfo = keyInfo
};
signedXml.Signature.Id = Constants.PackageSignatureId;
signedXml.SignedInfo.SignatureMethod = Constants.SignatureMethod;
signedXml.AddReference(CreatePackageObjectReference());
signedXml.AddObject(CreatePackageObject(openXmlPackage.Package, hashAlgorithm));
signedXml.ComputeSignature();
XmlElement signature = signedXml.GetXml();
// Get or create the DigitalSignatureOriginPart.
DigitalSignatureOriginPart dsOriginPart =
openXmlPackage.GetPartsOfType <DigitalSignatureOriginPart>().FirstOrDefault() ??
openXmlPackage.AddNewPart <DigitalSignatureOriginPart>();
var xmlSignaturePart = dsOriginPart.AddNewPart <XmlSignaturePart>();
// Write the Signature XmlElement to the XmlSignaturePart.
using Stream stream = xmlSignaturePart.GetStream(FileMode.Create, FileAccess.Write);
using XmlWriter writer = XmlWriter.Create(stream);
signature.WriteTo(writer);
}
private void SetDigitalSignatureOriginPartbyDocumentType()
{
if (DocumentType == Types.WordProcessingML)
{
digSigOrigin = WordprocessingDocument.Open(package).DigitalSignatureOriginPart;
}
if (DocumentType == Types.SpreadSheetML)
{
digSigOrigin = SpreadsheetDocument.Open(package).DigitalSignatureOriginPart;
}
if (DocumentType == Types.PresentationML)
{
digSigOrigin = PresentationDocument.Open(package).DigitalSignatureOriginPart;
}
signers = GetDigitalSigners();
}
