数字签名签名者名称未显示

如何解决数字签名签名者名称未显示

在C＃中，当由Itextsharp库签名时，为什么不在pdf中显示签名者名称？ 我尝试通过数字证书USB令牌创建签名的PDF。当我在每个页面上生成签名时，该时间签名无法显示歌手姓名。

以下是获取证书的代码：

X509Certificate2 certClient = null;
X509Store st = new X509Store(StoreName.My,StoreLocation.CurrentUser);
string filename = @"..\List1.pdf";
st.Open(OpenFlags.MaxAllowed);
X509Certificate2Collection collection = st.Certificates;
foreach (X509Certificate2 cert in collection)
{                    
    if (cert.Subject.ToLower().Contains("serialnumber"))
    {
        certClient = cert;
        string username = certClient.Subject;
        string startdate = certClient.GetEffectiveDateString();
        string enddate = certClient.GetExpirationDateString();           
    }
}          
st.Close();
IList<X509Certificate> chain = new List<X509Certificate>();
X509Chain x509Chain = new X509Chain();
x509Chain.Build(certClient);
foreach (X509ChainElement x509ChainElement in x509Chain.ChainElements)
{
     chain.Add(DotNetUtilities.FromX509Certificate(x509ChainElement.Certificate));
}
PdfReader inputPdf = new PdfReader(filename);
string dest = @"..\sign10a.pdf";
PdfReader reader = new PdfReader(filename);
FileStream os = new FileStream(dest,FileMode.Create,FileAccess.Write);
PdfStamper stamper = PdfStamper.CreateSignature(reader,os,'\0');
PdfSignatureAppearance appearance = stamper.SignatureAppearance;
appearance.Acro6Layers = false;
appearance.Image = null;
appearance.SignatureRenderingMode = PdfSignatureAppearance.RenderingMode.DESCRIPTION;
appearance.SetVisibleSignature(new iTextSharp.text.Rectangle(100,10,250,100),reader.NumberOfPages,null);
IExternalSignature externalSignature1 = new X509Certificate2Signature(certClient,"SHA-256"); 
AllPagesSignatureContainer allPagesContainer = new AllPagesSignatureContainer(appearance,externalSignature1,chain);
MakeSignature.SignExternalContainer(appearance,allPagesContainer,8192);
reader.Close();
stamper.Dispose();

这是我的多个外观代码：

public class AllPagesSignatureContainer : IExternalSignatureContainer
{
    public AllPagesSignatureContainer(PdfSignatureAppearance appearance,IExternalSignature externalSignature,ICollection<X509Certificate> chain)
    {
        this.appearance = appearance;
        this.chain = chain;
        this.externalSignature = externalSignature;
    }

    public void ModifySigningDictionary(PdfDictionary signDic)
    {
        signDic.Put(PdfName.FILTER,PdfName.ADOBE_PPKMS);
        signDic.Put(PdfName.SUBFILTER,PdfName.ADBE_PKCS7_DETACHED);
        PdfStamper stamper = appearance.Stamper;
        PdfReader reader = stamper.Reader;
        PdfDictionary xobject1 = new PdfDictionary();
        PdfDictionary xobject2 = new PdfDictionary();
        xobject1.Put(PdfName.N,appearance.GetAppearance().IndirectReference);
        xobject2.Put(PdfName.AP,xobject1);
        PdfIndirectReference PRef = stamper.Writer.PdfIndirectReference;
        PdfLiteral PRefLiteral = new PdfLiteral((PRef.Number + 1 + 2 * (reader.NumberOfPages - 1)) + " 0 R");

        for (int i = 1; i < reader.NumberOfPages; i++)
        {
            var signatureField = PdfFormField.CreateSignature(stamper.Writer);
            signatureField.Put(PdfName.T,new PdfString("ClientSignature_" + i.ToString()));
            signatureField.Put(PdfName.V,PRefLiteral);
            signatureField.Put(PdfName.F,new PdfNumber("132"));
            signatureField.SetWidget(appearance.Rect,null);
            signatureField.Put(PdfName.SUBTYPE,PdfName.WIDGET);
            signatureField.Put(PdfName.AP,xobject1);
            signatureField.SetPage();
            Console.WriteLine(signatureField);

            stamper.AddAnnotation(signatureField,i);
        }
    }

    public byte[] Sign(Stream data)
    {
        String hashAlgorithm = externalSignature.GetHashAlgorithm();
        PdfPKCS7 sgn = new PdfPKCS7(null,chain,hashAlgorithm,false);
        IDigest messageDigest = DigestUtilities.GetDigest(hashAlgorithm);
        byte[] hash = DigestAlgorithms.Digest(data,hashAlgorithm);
        byte[] sh = sgn.getAuthenticatedAttributeBytes(hash,null,CryptoStandard.CMS);
        byte[] extSignature = externalSignature.Sign(sh);
        sgn.SetExternalDigest(extSignature,externalSignature.GetEncryptionAlgorithm());
        return sgn.GetEncodedPKCS7(hash,CryptoStandard.CMS);            
    }
    PdfSignatureAppearance appearance;
    ICollection<X509Certificate> chain;
    IExternalSignature externalSignature;
}

数字签名显示多页，但无法显示签名者名称。

我希望对您有所帮助，我从Internet上的示例中编写了代码。它会起作用，但只显示歌手姓名。

解决方法

你想知道为什么在你的可视化中

“数字签名”后没有名称。

iTextSharp 像这样创建文本行：

buf.Append("Digitally signed by ");
String name = null;
CertificateInfo.X509Name x500name = CertificateInfo.GetSubjectFields((X509Certificate)signCertificate);
if (x500name != null) {
    name = x500name.GetField("CN");
    if (name == null)
        name = x500name.GetField("E");
}
if (name == null)
    name = "";
buf.Append(name).Append('\n');

（摘自PdfSignatureAppearance.GetAppearance()）

signCertificate 此处是 BouncyCastle X509Certificate，否则可通过 PdfSignatureAppearance 属性 Certificate 访问。

但是在您的代码中，您没有设置该 appearance.Certificate 属性。因此，在上面的代码中，x500Name 是 null。因此，name 是 ""，并且在 "Digitally signed by " 之后没有添加名称。

如果您希望 iText 自动填写该字段，请提供必要的信息并设置 appearance.Certificate。或者，您可以自己生成外观。