c# – 使用iTextSharp 5.3.3和USB令牌签名PDF

我是iTextSharp(和StackOverFlow)的新手.我正在尝试使用外部USB令牌在C#中签名PDF.我尝试使用我从互联网上挖掘的以下代码.

Org.BouncyCastle.X509.X509CertificateParser cp = new Org.BouncyCastle.X509.X509CertificateParser();

//Get Sertifiacte
X509Certificate2 certClient = null;
X509Store st = new X509Store(StoreName.My,StoreLocation.CurrentUser);
st.Open(OpenFlags.MaxAllowed);
X509Certificate2Collection collection = X509Certificate2UI.SelectFromCollection(st.Certificates,"Please choose certificate:","",X509SelectionFlag.SingleSelection);
if (collection.Count > 0){
   certClient = collection[0];
}
st.Close();
//Get Cert Chain
IList<Org.BouncyCastle.X509.X509Certificate> chain = new List<Org.BouncyCastle.X509.X509Certificate>();
X509Chain x509chain = new X509Chain();
x509chain.Build(certClient );
foreach (X509ChainElement x509ChainElement in x509chain.ChainElements){
    chain.Add(DotNetUtilities.FromX509Certificate(x509ChainElement.Certificate));
}

PdfReader reader = new PdfReader(sourceDocument);
FileStream resstream = new FileStream(resultDocument,FileMode.Create,FileAccess.ReadWrite);

pdfstamper stamper = pdfstamper.CreateSignature(reader,resstream,'\0',null,true);

PdfSignatureAppearance appearance = stamper.SignatureAppearance;
appearance.Reason = reason;
appearance.Location = location;
appearance.SetVisibleSignature(new iTextSharp.text.Rectangle(20,10,170,60),1,"Signed");

X509Certificate2Signature es = new X509Certificate2Signature(certClient,"SHA-1");
MakeSignature.SignDetached(appearance,es,chain,CryptoStandard.CMS);

问题是我收到一个例外：

System.Security.Cryptography.CryptographicException was unhandled
  Message=Invalid type specified.

  Source=mscorlib
  StackTrace:
       at System.Security.Cryptography.CryptographicException.ThrowCryptographicException(Int32 hr)
       at System.Security.Cryptography.Utils._GetKeyParameter(SafeKeyHandle hKey,UInt32 paramID)
       at System.Security.Cryptography.Utils.GetKeyPairHelper(CspAlgorithmType keyType,CspParameters parameters,Boolean randomKeyContainer,Int32 dwKeySize,SafeProvHandle& safeProvHandle,SafeKeyHandle& safeKeyHandle)
       at System.Security.Cryptography.RSACryptoServiceProvider.GetKeyPair()
       at System.Security.Cryptography.RSACryptoServiceProvider..ctor(Int32 dwKeySize,Boolean useDefaultKeySize)
       at System.Security.Cryptography.X509Certificates.X509Certificate2.get_PrivateKey()
       at iTextSharp.text.pdf.security.X509Certificate2Signature..ctor(X509Certificate2 certificate,String hashAlgorithm)
       at WindowsFormsApplication1.PDFSignerHelper.signPdfFile(String sourceDocument,String resultDocument,X509Certificate2 certClient,String reason,String location)
  InnerException:

解决方法

这种方法对我们来说很好(iTextSharp 5.3.3).我们使用智能卡和USB令牌(供应商 – www.author.kiev.ua)：

X509Store store = new X509Store(StoreLocation.CurrentUser);
            store.Open(OpenFlags.ReadOnly);
            X509Certificate2Collection sel = X509Certificate2UI.SelectFromCollection(store.Certificates,X509SelectionFlag.SingleSelection);

            X509Certificate2 cert = sel[0];

            Org.BouncyCastle.X509.X509CertificateParser cp = new Org.BouncyCastle.X509.X509CertificateParser();
            Org.BouncyCastle.X509.X509Certificate[] chain = new Org.BouncyCastle.X509.X509Certificate[] {
            cp.ReadCertificate(cert.RawData)};

            IExternalSignature externalSignature = new X509Certificate2Signature(cert,"SHA-1");

            PdfReader pdfReader = new PdfReader(pathToBasePdf);

            signedPdf = new FileStream(pathToBasePdf,FileMode.Create);

            pdfstamper = pdfstamper.CreateSignature(pdfReader,signedPdf,'\0');
            PdfSignatureAppearance signatureAppearance = pdfstamper.SignatureAppearance;

            signatureAppearance.SignatureGraphic = Image.GetInstance(pathToSignatureImage);
            signatureAppearance.SetVisibleSignature(new Rectangle(100,100,250,150),pdfReader.NumberOfPages,"Signature");
            signatureAppearance.SignatureRenderingMode = PdfSignatureAppearance.RenderingMode.GRAPHIC_AND_DESCRIPTION;

            MakeSignature.SignDetached(signatureAppearance,externalSignature,CryptoStandard.CMS);