C#-ITextSharp SetVisibleSignature无法按预期工作
作者：互联网
因此,我一直在使用IText的Java实现,但是现在我几乎将签名过程的一部分写到了C#中,并且遇到了麻烦.因此,当我使用SetVisibleSignature(rect,page,name)重载对我的文档进行签名时,它将按预期方式对文档进行签名(只要签名字段不存在),但是当我使用重载SetVisibleSignature(name)来对现有文档进行签名时字段,它实际上并不签署文档.我是否正在做一些愚蠢的事情而错过了什么？
感谢您的任何帮助.
更新的代码
using iTextSharp.text;
using iTextSharp.text.pdf;
using iTextSharp.text.pdf.security;
using Org.BouncyCastle.Security;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Security.Cryptography;
using System.Security.Cryptography.X509Certificates;
using BouncyCastle = Org.BouncyCastle;
public class DocumentSigner : IDocumentSigner
{
private const string _datetimeFormat = "dd/MM/yyyy hh:mm:ss";
private readonly IDateTimeProvider _dateTimeProvider;
private readonly ISettingManager _settingManager;
public DocumentSigner(IDateTimeProvider dateTimeProvider, ISettingManager settingManager)
{
Guard.ArgumentNotNull(dateTimeProvider, "dateTimeProvider");
Guard.ArgumentNotNull(settingManager, "settingManager");
_dateTimeProvider = dateTimeProvider;
_settingManager = settingManager;
}
public byte[] Sign(Certificate certificate, SigningInformation information, List<SigningBlock> signingBlocks, List<MemberItemSignature> signatureImages, byte[] document, bool certify)
{
document = AddMetaData(information, document);
document = AddSignatureFields(information, signingBlocks, document);
return SignDocument(certificate, information, signingBlocks, signatureImages, document, certify);
}
private byte[] AddMetaData(SigningInformation information, byte[] document)
{
if (information.CustomProperties != null && information.CustomProperties.Any())
{
using (MemoryStream outputStream = new MemoryStream())
{
using (PdfReader reader = new PdfReader(document))
{
using (PdfStamper stamper = new PdfStamper(reader, outputStream, '\0', true))
{
Dictionary<string, string> currentProperties = reader.Info;
foreach (string key in information.CustomProperties.Keys)
{
if (currentProperties.ContainsKey(key))
{
currentProperties[key] = information.CustomProperties[key];
}
else
{
currentProperties.Add(key, information.CustomProperties[key]);
}
}
stamper.MoreInfo = currentProperties;
}
}
return outputStream.ToArray();
}
}
return document;
}
private byte[] AddSignatureFields(SigningInformation information, List<SigningBlock> signingBlocks, byte[] document)
{
for (int i = 0; i < signingBlocks.Count; i++)
{
using (MemoryStream outputStream = new MemoryStream())
{
using (PdfReader reader = new PdfReader(document))
{
using (PdfStamper stamper = new PdfStamper(reader, outputStream, '\0', true))
{
CreateSignatureField(reader, stamper, signingBlocks[i]);
}
}
document = outputStream.ToArray();
}
}
return document;
}
private PdfSignatureAppearance CreatePdfAppearance(PdfStamper stamper, SigningInformation information, bool certify)
{
PdfSignatureAppearance appearance = stamper.SignatureAppearance;
appearance.Location = information.Location;
appearance.Reason = information.Purpose;
appearance.SignatureRenderingMode = PdfSignatureAppearance.RenderingMode.DESCRIPTION;
CreatePdfAppearanceCertifyDocument(appearance, certify);
return appearance;
}
private void CreatePdfAppearanceCertifyDocument(PdfSignatureAppearance appearance, bool certify)
{
if (certify)
{
appearance.CertificationLevel = PdfSignatureAppearance.CERTIFIED_FORM_FILLING;
}
else
{
appearance.CertificationLevel = PdfSignatureAppearance.NOT_CERTIFIED;
}
}
private PdfStamper CreatePdfStamper(PdfReader reader, MemoryStream outputStream, byte[] document)
{
return PdfStamper.CreateSignature(reader, outputStream, '\0', null, true);
}
private void CreateSignatureField(PdfReader reader, PdfStamper stamper, SigningBlock signingBlock)
{
if (signingBlock == null)
{
return;
}
if (!DoesSignatureFieldExist(reader, signingBlock.Name))
{
PdfFormField signatureField = PdfFormField.CreateSignature(stamper.Writer);
signatureField.SetWidget(new Rectangle(signingBlock.X, signingBlock.Y, signingBlock.X + signingBlock.Width, signingBlock.Y + signingBlock.Height), null);
signatureField.Flags = PdfAnnotation.FLAGS_PRINT;
signatureField.FieldName = signingBlock.Name;
signatureField.Page = signingBlock.Page;
stamper.AddAnnotation(signatureField, signingBlock.Page);
}
}
private bool DoesSignatureFieldExist(PdfReader reader, string signatureFieldName)
{
if (String.IsNullOrWhiteSpace(signatureFieldName))
{
return false;
}
return reader.AcroFields.DoesSignatureFieldExist(signatureFieldName);
}
private byte[] GetSignatureImage(List<MemberItemSignature> signatureImages, string signingBlockName)
{
MemberItemSignature signature = signingBlockName.Contains("Initial") ? signatureImages.Where(image => image.Use == SignatureUses.Initial).FirstOrDefault() : signatureImages.Where(image => image.Use == SignatureUses.Signature).FirstOrDefault();
if (signature != null)
{
return signature.Image;
}
else
{
return null;
}
}
private byte[] SignDocument(Certificate certificate, SigningInformation information, List<SigningBlock> signingBlocks, List<MemberItemSignature> signatureImages, byte[] document, bool certify)
{
for (int i = 0; i < signingBlocks.Count; i++)
{
using (MemoryStream outputStream = new MemoryStream())
{
using (PdfReader reader = new PdfReader(document))
{
using (PdfStamper stamper = CreatePdfStamper(reader, outputStream, document))
{
SigningBlock signingBlock = signingBlocks[i];
PdfSignatureAppearance appearance = CreatePdfAppearance(stamper, information, certify && i == 0);
SignDocumentSigningBlock(certificate, information, signingBlock, appearance, stamper, GetSignatureImage(signatureImages, signingBlock.Name));
}
}
document = outputStream.ToArray();
}
}
return document;
}
private void SignDocumentSigningBlock(Certificate certificate, SigningInformation information, SigningBlock block, PdfSignatureAppearance appearance, PdfStamper stamper, byte[] signatureImage)
{
X509Certificate2 x509Certificate = new X509Certificate2(certificate.Bytes, certificate.Password, X509KeyStorageFlags.Exportable);
appearance.SetVisibleSignature(block.Name);
SignDocumentSigningBlockWithImage(signatureImage, appearance);
SignDocumentSigningBlockWithText(appearance, x509Certificate);
using (RSACryptoServiceProvider rsa = (RSACryptoServiceProvider)x509Certificate.PrivateKey)
{
IExternalSignature externalSignature = new PrivateKeySignature(DotNetUtilities.GetRsaKeyPair(rsa).Private, _settingManager["DocumentSigningEncryptionHashAlgorithm"]);
MakeSignature.SignDetached(appearance, externalSignature, new BouncyCastle::X509.X509Certificate[] { DotNetUtilities.FromX509Certificate(x509Certificate) }, null, null, new TSAClientBouncyCastle(_settingManager["DocumentSigningTimestampingServiceAddress"]), Int32.Parse(_settingManager["DocumentSigningEstimatedTimestampSize"]), CryptoStandard.CMS);
}
}
private void SignDocumentSigningBlockWithImage(byte[] signatureImage, PdfSignatureAppearance appearance)
{
if (signatureImage != null && signatureImage.Length > 0)
{
Image signatureImageInstance = Image.GetInstance(signatureImage);
appearance.Image = signatureImageInstance;
appearance.SignatureGraphic = signatureImageInstance;
}
}
private void SignDocumentSigningBlockWithText(PdfSignatureAppearance appearance, X509Certificate2 x509Certificate)
{
if (x509Certificate == null)
{
return;
}
appearance.Layer2Text = SignDocumentSigningBlockWithTextBuildText(x509Certificate);
appearance.Layer2Font = new Font(Font.FontFamily.COURIER, 7.0f, Font.NORMAL, BaseColor.LIGHT_GRAY);
appearance.Acro6Layers = true;
}
private string SignDocumentSigningBlockWithTextBuildText(X509Certificate2 x509Certificate)
{
Dictionary<string, string> fields = SignDocumentSigningBlockWithTextBuildTextIssuerFields(x509Certificate.IssuerName.Name);
string organization = fields.Keys.Contains("O") ? fields["O"] : String.Empty;
string commonName = fields.Keys.Contains("CN") ? fields["CN"] : String.Empty;
string signDate = _dateTimeProvider.Now.ToString(_datetimeFormat);
string expirationDate = x509Certificate.NotAfter.ToString(_datetimeFormat);
return "Digitally signed by " + organization + "\nSignee: " + commonName + "\nSign date: " + signDate + "\n" + "Expiration date: " + expirationDate;
}
private Dictionary<string, string> SignDocumentSigningBlockWithTextBuildTextIssuerFields(string issuer)
{
Dictionary<string, string> fields = new Dictionary<string, string>();
string[] issuerFields = issuer.Split(',');
foreach (string field in issuerFields)
{
string[] fieldSplit = field.Split('=');
string key = fieldSplit[0].Trim();
string value = fieldSplit[1].Trim();
if (!fields.Keys.Contains(key))
{
fields.Add(key, value);
}
else
{
fields[key] = value;
}
}
return fields;
}
}
价值观
_settingManager["DocumentSigningEncryptionHashAlgorithm"] = "SHA-256";
_settingManager["DocumentSigningTimestampingServiceAddress"] = "http://services.globaltrustfinder.com/adss/tsa";
_settingManager["DocumentSigningEstimatedTimestampSize"] = 104000;
解决方法:
OP提供的代码引用并访问多个未知类的对象.因此,为了使其可运行,必须将其缩减为独立的.
精简版仍然可以用来重现和分析问题,请参见.脚本后.此后的任何声明均基于此简化版本的行为.
OP所观察到的问题可以使用iTextSharp 5.5.7(和类似地使用iText 5.5.7)进行复制,也非常有趣的是,不能使用任一库的5.5.6版本进行复制.随着我对Java的深入了解,我研究了iText中的更改.它们已经以非常忠实的方式移植到了iTextSharp.
确实,此问题是一个回归,在iText(Sharp)5.5.7中,在附加模式下对先前存在的空签名字段进行签名已损坏.
在5.5.6和5.5.7之间,对PdfSignatureAppearance.preClose进行了更改.如果对现有签名字段进行签名,则该代码用于处理相关签名字段的第一个小部件(af.getFieldItem(name).getWidget(0)),现在可在关联的合并字典(af.getFieldItem(name))上运行.getMerged(0)).
不幸的是,尽管前者实际上是原始PDF中存在的一个对象,因此调用writer.markUsed标记了它的更改内容以写入增量更新部分,但后者并不对应于原始PDF中的对象(它是多个对象的虚拟集合),因此调用writer.markUsed不会再将要写入的更改标记为增量更新.
因此,尽管实际签名值仍被写入文件,但它不再连接到指定的签名字段.
所做的更改已修复方法行为.
Before this
preClosedworked incorrectly because it retrieved field dictionary as widget annotation. It’s incorrect in case when field and widget dicts are not merged. In case they were merged, everything worked as expected. The latter is the most possible case for digital signature fields, but it isn’t obligated according to spec.(DEV-1448)
这是正确的,如果字段和窗口小部件字典分开,则必须对该字段(而不是窗口小部件)进行某些更改.只是实现无法在附加模式下按预期工作.
PS：这是OP代码的简化版本：
public class DocumentSigner
{
private const string _datetimeFormat = "dd/MM/yyyy hh:mm:ss";
public byte[] Sign(ICollection<X509Certificate> chain, ICipherParameters pk, string signingBlock, byte[] document, bool certify, String pattern = null)
{
document = AddMetaData(document);
if (pattern != null)
File.WriteAllBytes(String.Format(pattern, "1"), document);
document = AddSignatureFields(signingBlock, document);
if (pattern != null)
File.WriteAllBytes(String.Format(pattern, "2"), document);
return SignDocument(chain, pk, signingBlock, document, certify);
}
private byte[] AddMetaData(byte[] document)
{
return document;
}
private byte[] AddSignatureFields(string signingBlock, byte[] document)
{
using (MemoryStream outputStream = new MemoryStream())
{
using (PdfReader reader = new PdfReader(document))
{
using (PdfStamper stamper = new PdfStamper(reader, outputStream, '\0', true))
{
CreateSignatureField(reader, stamper, signingBlock);
}
}
document = outputStream.ToArray();
}
return document;
}
private PdfSignatureAppearance CreatePdfAppearance(PdfStamper stamper, bool certify)
{
PdfSignatureAppearance appearance = stamper.SignatureAppearance;
appearance.Location = "information.Location";
appearance.Reason = "information.Purpose";
appearance.SignatureRenderingMode = PdfSignatureAppearance.RenderingMode.DESCRIPTION;
CreatePdfAppearanceCertifyDocument(appearance, certify);
return appearance;
}
private void CreatePdfAppearanceCertifyDocument(PdfSignatureAppearance appearance, bool certify)
{
if (certify)
{
appearance.CertificationLevel = PdfSignatureAppearance.CERTIFIED_FORM_FILLING;
}
else
{
appearance.CertificationLevel = PdfSignatureAppearance.NOT_CERTIFIED;
}
}
private PdfStamper CreatePdfStamper(PdfReader reader, MemoryStream outputStream, byte[] document)
{
return PdfStamper.CreateSignature(reader, outputStream, '\0', null, true);
}
private void CreateSignatureField(PdfReader reader, PdfStamper stamper, string signingBlock)
{
if (signingBlock == null)
{
return;
}
if (!DoesSignatureFieldExist(reader, signingBlock))
{
PdfFormField signatureField = PdfFormField.CreateSignature(stamper.Writer);
signatureField.SetWidget(new Rectangle(100, 100, 200, 200), null);
signatureField.Flags = PdfAnnotation.FLAGS_PRINT;
signatureField.FieldName = signingBlock;
signatureField.Page = 1;
stamper.AddAnnotation(signatureField, 1);
}
}
private bool DoesSignatureFieldExist(PdfReader reader, string signatureFieldName)
{
if (String.IsNullOrWhiteSpace(signatureFieldName))
{
return false;
}
return reader.AcroFields.DoesSignatureFieldExist(signatureFieldName);
}
private byte[] GetSignatureImage(string signingBlockName)
{
return null;
}
private byte[] SignDocument(ICollection<X509Certificate> chain, ICipherParameters pk, string signingBlock, byte[] document, bool certify)
{
using (MemoryStream outputStream = new MemoryStream())
{
using (PdfReader reader = new PdfReader(document))
{
using (PdfStamper stamper = CreatePdfStamper(reader, outputStream, document))
{
PdfSignatureAppearance appearance = CreatePdfAppearance(stamper, certify);
SignDocumentSigningBlock(chain, pk, signingBlock, appearance, stamper, GetSignatureImage(signingBlock));
}
}
document = outputStream.ToArray();
}
return document;
}
private void SignDocumentSigningBlock(ICollection<X509Certificate> chain, ICipherParameters pk, string block, PdfSignatureAppearance appearance, PdfStamper stamper, byte[] signatureImage)
{
appearance.SetVisibleSignature(block);
SignDocumentSigningBlockWithImage(signatureImage, appearance);
SignDocumentSigningBlockWithText(appearance, chain.First());
IExternalSignature externalSignature = new PrivateKeySignature(pk, "SHA-256");
MakeSignature.SignDetached(appearance, externalSignature, chain, null, null, new TSAClientBouncyCastle("http://services.globaltrustfinder.com/adss/tsa"), 104000, CryptoStandard.CMS);
}
private void SignDocumentSigningBlockWithImage(byte[] signatureImage, PdfSignatureAppearance appearance)
{
if (signatureImage != null && signatureImage.Length > 0)
{
Image signatureImageInstance = Image.GetInstance(signatureImage);
appearance.Image = signatureImageInstance;
appearance.SignatureGraphic = signatureImageInstance;
}
}
private void SignDocumentSigningBlockWithText(PdfSignatureAppearance appearance, X509Certificate x509Certificate)
{
if (x509Certificate == null)
{
return;
}
appearance.Layer2Text = SignDocumentSigningBlockWithTextBuildText(x509Certificate);
appearance.Layer2Font = new Font(Font.FontFamily.COURIER, 7.0f, Font.NORMAL, BaseColor.LIGHT_GRAY);
appearance.Acro6Layers = true;
}
private string SignDocumentSigningBlockWithTextBuildText(X509Certificate x509Certificate)
{
Dictionary<string, string> fields = SignDocumentSigningBlockWithTextBuildTextIssuerFields(x509Certificate.IssuerDN.ToString());
string organization = fields.Keys.Contains("O") ? fields["O"] : String.Empty;
string commonName = fields.Keys.Contains("CN") ? fields["CN"] : String.Empty;
string signDate = System.DateTime.Now.ToString(_datetimeFormat);
string expirationDate = x509Certificate.NotAfter.ToString();
return "Digitally signed by " + organization + "\nSignee: " + commonName + "\nSign date: " + signDate + "\n" + "Expiration date: " + expirationDate;
}
private Dictionary<string, string> SignDocumentSigningBlockWithTextBuildTextIssuerFields(string issuer)
{
Dictionary<string, string> fields = new Dictionary<string, string>();
string[] issuerFields = issuer.Split(',');
foreach (string field in issuerFields)
{
string[] fieldSplit = field.Split('=');
string key = fieldSplit[0].Trim();
string value = fieldSplit[1].Trim();
if (!fields.Keys.Contains(key))
{
fields.Add(key, value);
}
else
{
fields[key] = value;
}
}
return fields;
}
}
PPS：Java / iText测试使用ComplexSignatureFields.java中的signTest_2_user2699460单元测试完成,该单元测试适用于test-2-user2699460.pdf(上面的C#代码的中间输出).
PPPS：同时,导致回归的更改已回滚：
Returned the use of .getWidget method instead of .getMerged since the case, when signature field dictionary and dictionary its widget annotation are not merged, is rather uncommon if can be encountered at all. Moreover the use of merged dictionary instead of widget requires more efforts since .getMerged method returns not actually the dictionary obtained by merging signature field dict and widget annotation dict, but also AcroForm dict.
(DEV-1579)
因此,回归很可能将在5.5.8版中解决
标签：signing,pdf,itextsharp,c 来源： https://codeday.me/bug/20191027/1947649.html