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我正在尝试对任何给定pdf的每个页面进行数字签名。但它只在第一页或最后一页签字。我想我已经知道问题出在MakeSignature.SignDetached（）方法。此方法关闭所有流并关闭pdf以进行进一步签名。如何在没有MakeSignature.SignDetached（）方法的情况下对pdf进行数字签名？
我的代码：
public static void SignInForEveryPage(string input, string output, PDFEncryption pdfEnc, bool encrypt, bool passCheck, string pass) {
X509CertificateParser cp = new X509CertificateParser();
X509Certificate[] chain = { cp.ReadCertificate(CertInfo.MyCert.RawData) };
IExternalSignature externalSignature = new X509Certificate2Signature(CertInfo.MyCert, "SHA-1");
//Setup signature
if(File.Exists(output)) {
File.Delete(output);
}
PdfSignatureAppearance signatureAppearance=null;
PdfSignatureAppearance tempAppearance = null;
PdfReader reader = new PdfReader(input);
FileStream firstFileStream = new FileStream(output, FileMode.Create, FileAccess.ReadWrite);
PdfStamper pdfStamper = PdfStamper.CreateSignature(reader, firstFileStream, '\0', null, true);
for(int index = 1; index <= reader.NumberOfPages; index++) {
if(encrypt && pdfEnc != null) {
pdfEnc.Encrypt(pdfStamper);
}
if(passCheck) {
pdfStamper.SetEncryption(PdfWriter.STRENGTH128BITS, "123", "123", PdfWriter.ALLOW_COPY);
//Set password of output file
}
//Write the metadata
pdfStamper.MoreInfo = MetaData.GetMetaData();
pdfStamper.XmpMetadata = MetaData.GetStreamedMetaData();
//Set signature appearance
signatureAppearance = pdfStamper.SignatureAppearance;
signatureAppearance.Reason = ReasonText; //Reason
signatureAppearance.Contact = ContactText; //Contact
signatureAppearance.Location = LocationText; //Location
byte[] rawData = null;
var customText = "";
//Set the text shown in signature
customText += "Digitally Signed by:\n";
customText += CertInfo.CertName + "\n";
if(!string.IsNullOrEmpty(LocationText)) {
customText += "Location: ";
customText += LocationText + "\n";
}
if(!string.IsNullOrEmpty(ReasonText)) {
customText += "Reason: ";
customText += ReasonText + "\n";
}
customText += "Date: ";
customText += DateTimeOffset.Now.ToString("yyyy-MM-dd HH:mm:ss K") + "\n";
customText = customText.TrimEnd();
//set the image shown in signature
if(ShowImage && SignaturePictureImage != null) {
using(MemoryStream memoryStream = new MemoryStream()) {
SignaturePictureImage.Save(memoryStream, ImageFormat.Bmp);
rawData = memoryStream.ToArray();
}
}
//For signature position and size
var sigX = Mm2Pt(LeftNumValue);
var sigY = Mm2Pt(BottomNumValue);
var sigW = Mm2Pt(WidthNumValue);
var sigH = Mm2Pt(HeightNumValue);
//Draw the rectangle for signature field
//pdfStamper.Reader.GetPageSize(index);
signatureAppearance.SignatureGraphic = rawData == null ? null : iTextSharp.text.Image.GetInstance(rawData);
signatureAppearance.Layer2Text = customText;
signatureAppearance.Layer4Text = ""; //if null or not set then it will show 'signature not valid'
signatureAppearance.Acro6Layers = true;
if(signatureAppearance.SignatureGraphic != null) {
signatureAppearance.SignatureRenderingMode = PdfSignatureAppearance.RenderingMode.GRAPHIC_AND_DESCRIPTION;
//show image first then text in the signature
}
signatureAppearance.SetVisibleSignature(new Rectangle(sigX, sigY, sigX + sigW, sigY + sigH), index, null);
signatureAppearance.GetLayer(1);
tempAppearance = signatureAppearance;
MakeSignature.SignDetached(tempAppearance, externalSignature, chain, null, null, null, 0, CryptoStandard.CMS);
}
}
我使用iTextSharp的库。有没有解决这个问题的方法？
严格地说，“[如何使用iText在所有文档的页面中显示数字PDF签名]（http://stackoverflow.com/a/35724742/1729265）”是关于iText，而不是iTextSharp，但来自那里的参数保持一致。 – mkl
谢谢@mkl，我不知道同比对所有论点做了概述。我刚刚提出了它。 –
@furiousNoob *此方法关闭所有流并关闭pdf以进行进一步签名。* - 如果您已经意识到集成PDF签名的问题，请选择“多个签名（每页一个），每个单独一个可视化文件”我引用的答案，现在有实施困难，请相应更新您的问题。它最终会重新打开并回答。 – mkl