所以我遇到了一个有趣的问题。所以我知道在itext/itextsharp中，当你签名时，有一个关于PdfSignatureAppearance的设置，你可以设置CertificateLevel，这正如预期的那样，但最近我遇到了一个问题，我在签署一个文件时，该文件中的第一个签名是用PdfSignature Appearance.CERTIFIED_FORM_FILLING签名的，从而允许我使用（PdfSignatureAppearance.NOT_CERTIFIED）添加/签署签名，该签名用作批准签名。
所以我问这个问题的原因是我遇到了一个问题，我有一个文档，文档中有现有的签名字段，我用PdfSignatureAppearance.CERTIFIED_FORM_FILLING签署第一个签名，然后用PdfSignatureAppearance.NOT_CERTIFIED签署签名，但当我签署第二个签名字段时，第一个签名字段无效。
我使用的这个文档是使用FoxitPro创建的，但如果我在Adobe DC Pro中做同样的事情，它会像预期的那样工作。
如有任何建议，我们将不胜感激。
这是我用来签署pdf文档的代码，它只是signer类，所以其他对象和对该类的引用将丢失。
public byte[] Sign(SignRequest request)
{
request.Document = SaveDocumentChanges(new SaveRequest
{
Document = request.Document,
FormFields = request.FormFields,
SigningBlocks = request.SigningBlocks
}, request.Information);
return SignDocument(request.Certificate, request.Information, request.SigningBlocks, request.SignatureImages, request.Document, request.IsFinalSignature);
}
private byte[] AddFormFields(List<FormField> formFields, byte[] document)
{
for (int i = 0; i < formFields.Count; i++)
{
using (MemoryStream outputStream = new MemoryStream())
{
using (PdfReader reader = new PdfReader(document))
{
using (PdfStamper stamper = CreatePdfStamper(reader, outputStream, false))
{
if (!DoesFormFieldExist(reader, formFields[i].Name))
{
CreateFormField(reader, stamper, formFields[i]);
}
else
{
UpdateFormField(stamper, formFields[i]);
}
}
}
document = outputStream.ToArray();
}
}
return document;
}
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 = CreatePdfStamper(reader, outputStream, false))
{
Dictionary<string, string> currentProperties = reader.Info;
foreach (string key in information.CustomProperties.Keys)
{
AddMetaDataAddDictionaryValue(currentProperties, key, information.CustomProperties[key]);
}
AddMetaDataAddDictionaryValue(currentProperties, "Producer", "Signisure");
AddMetaDataAddDictionaryValue(currentProperties, "Creator", "Signisure");
AddMetaDataAddDictionaryValue(currentProperties, "Author", "Signisure");
stamper.MoreInfo = currentProperties;
}
}
return outputStream.ToArray();
}
}
return document;
}
private void AddMetaDataAddDictionaryValue(Dictionary<string, string> dictionary, string key, string value)
{
if (dictionary.ContainsKey(key))
{
dictionary[key] = value;
}
else
{
dictionary.Add(key, value);
}
}
private void AddMetaDataAddDictionaryValue(PdfDictionary dictionary, PdfName key, PdfObject value)
{
if (!dictionary.Keys.Contains(key))
{
dictionary.Put(key, value);
}
}
private byte[] AddSignatureFields(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 = CreatePdfStamper(reader, outputStream, false))
{
if (!DoesSignatureFieldExist(reader, signingBlocks[i].Name))
{
CreateSignatureField(stamper, signingBlocks[i]);
}
}
}
document = outputStream.ToArray();
}
}
return document;
}
private void CreateFormField(PdfReader reader, PdfStamper stamper, FormField formField)
{
TextField field = new TextField(stamper.Writer, new Rectangle(formField.X, formField.Y, formField.X + formField.Width, formField.Y + formField.Height), formField.Name);
field.Text = formField.Value;
field.Font = BaseFont.CreateFont(BaseFont.TIMES_ROMAN, BaseFont.CP1252, BaseFont.EMBEDDED);
field.FontSize = 12;
field.Options = TextField.READ_ONLY;
stamper.AddAnnotation(field.GetTextField(), formField.Page);
}
private PdfSignatureAppearance CreatePdfAppearance(PdfStamper stamper, SigningInformation information, string location, bool certify)
{
PdfSignatureAppearance appearance = stamper.SignatureAppearance;
appearance.SignatureRenderingMode = PdfSignatureAppearance.RenderingMode.DESCRIPTION;
CreatePdfAppearanceCertifyDocument(appearance, certify);
if (information != null)
{
appearance.Location = location != String.Empty ? String.Format("{0} ({1})", location, information.IPAddress) : information.IPAddress;
appearance.Reason = information.SignatoryReason;
appearance.Contact = String.Format("{0} ({1})", information.Signatory, information.SignatoryEmail);
}
return appearance;
}
private void CreatePdfAppearanceCertifyDocument(PdfSignatureAppearance appearance, bool certify)
{
if (certify)
{
appearance.CertificationLevel = PdfSignatureAppearance.CERTIFIED_FORM_FILLING_AND_ANNOTATIONS;
}
else
{
appearance.CertificationLevel = PdfSignatureAppearance.NOT_CERTIFIED;
}
}
private PdfStamper CreatePdfStamper(PdfReader reader, MemoryStream outputStream, bool isSignature)
{
if (CreatePdfStamperIsPDFADocument(reader))
{
if (isSignature)
{
return PdfAStamper.CreateSignature(reader, outputStream, _pdfVersion, null, true, PdfAConformanceLevel.PDF_A_1A);
}
else
{
return new PdfAStamper(reader, outputStream, _pdfVersion, true, PdfAConformanceLevel.PDF_A_1A);
}
}
else
{
if (isSignature)
{
return PdfStamper.CreateSignature(reader, outputStream, _pdfVersion, null, true);
}
else
{
return new PdfStamper(reader, outputStream, _pdfVersion, true);
}
}
}
private bool CreatePdfStamperIsPDFADocument(PdfReader reader)
{
if (reader.Metadata != null && reader.Metadata.Length > 0)
{
IXmpMeta xmpMeta = XmpMetaParser.Parse(reader.Metadata, null);
IXmpProperty pdfaidConformance = xmpMeta.GetProperty(XmpConst.NS_PDFA_ID, "pdfaid:conformance");
IXmpProperty pdfaidPart = xmpMeta.GetProperty(XmpConst.NS_PDFA_ID, "pdfaid:part");
if (pdfaidConformance == null || pdfaidPart == null)
{
return false;
}
return true;
}
return false;
}
private void CreateSignatureField(PdfStamper stamper, SigningBlock signingBlock)
{
if (signingBlock == null)
{
return;
}
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;
signatureField.Put(PdfName.CONTENTS, new PdfString(String.Empty));
CreateSignatureFieldAddLockProperties(signatureField, signingBlock, stamper);
stamper.AddAnnotation(signatureField, signingBlock.Page);
}
private void CreateSignatureFieldAddLockProperties(PdfFormField signatureField, SigningBlock signingBlock, PdfStamper stamper)
{
if (signingBlock.LinkedFormFields != null && signingBlock.LinkedFormFields.Count > 0)
{
PdfSigLockDictionary lockDictionary = new PdfSigLockDictionary(PdfSigLockDictionary.LockAction.INCLUDE, signingBlock.LinkedFormFields.ToArray());
signatureField.Put(PdfName.LOCK, stamper.Writer.AddToBody(lockDictionary).IndirectReference);
}
}
private bool DoesFormFieldExist(PdfReader reader, string formFieldName)
{
if (String.IsNullOrWhiteSpace(formFieldName))
{
return false;
}
return reader.AcroFields.Fields.Where(vp => vp.Key == formFieldName).Any();
}
private bool DoesSignatureFieldExist(PdfReader reader, string signatureFieldName)
{
if (String.IsNullOrWhiteSpace(signatureFieldName))
{
return false;
}
return reader.AcroFields.DoesSignatureFieldExist(signatureFieldName);
}
private AcroFields.FieldPosition GetAcroFieldByName(PdfStamper stamper, string signatureBlockName)
{
return stamper.AcroFields.GetFieldPositions(signatureBlockName).FirstOrDefault();
}
private List<string> GetAllSignatureFieldNames(PdfReader reader)
{
List<string> signatureFields = new List<string>();
signatureFields.AddRange(reader.AcroFields.GetBlankSignatureNames());
signatureFields.AddRange(reader.AcroFields.GetSignatureNames());
return signatureFields;
}
private void GetDocumentFormFieldsBuildFormFields(List<FormField> formFields, PdfReader reader, PdfStamper stamper)
{
List<string> signatureFields = GetAllSignatureFieldNames(reader);
foreach (KeyValuePair<string, AcroFields.Item> field in reader.AcroFields.Fields)
{
string fieldName = field.Key.ToString();
if (!signatureFields.Where(signatureFieldName => signatureFieldName == fieldName).Any())
{
string fieldValue = reader.AcroFields.GetField(field.Key.ToString());
AcroFields.FieldPosition formFieldPosition = GetAcroFieldByName(stamper, fieldName);
formFields.Add(GetDocumentFormFieldsBuildFormFieldsCreateField(formFieldPosition, fieldName, fieldValue));
}
}
}
private FormField GetDocumentFormFieldsBuildFormFieldsCreateField(AcroFields.FieldPosition formFieldPosition, string fieldName, string fieldValue)
{
return new FormField
{
Height = (int)formFieldPosition.position.Height,
Name = fieldName,
Page = formFieldPosition.page,
Width = (int)formFieldPosition.position.Width,
X = (int)formFieldPosition.position.Left,
Y = (int)formFieldPosition.position.Top,
Value = fieldValue
};
}
private void GetDocumentSignatureBlocksBuildSignatureBlocks(List<SigningBlock> signatureBlocks, List<string> signatureBlockNames, PdfReader reader, PdfStamper stamper, bool isSigned)
{
foreach (string signatureBlockName in signatureBlockNames)
{
AcroFields.FieldPosition signatureFieldPosition = GetAcroFieldByName(stamper, signatureBlockName);
signatureBlocks.Add(GetDocumentSignatureBlocksBuildSignatureBlocksCreateBlock(signatureFieldPosition, signatureBlockName, isSigned));
}
}
private SigningBlock GetDocumentSignatureBlocksBuildSignatureBlocksCreateBlock(AcroFields.FieldPosition signatureFieldPosition, string fieldName, bool isSigned)
{
return new SigningBlock
{
Height = (int)signatureFieldPosition.position.Height,
Name = fieldName,
Page = signatureFieldPosition.page,
Width = (int)signatureFieldPosition.position.Width,
X = (int)signatureFieldPosition.position.Left,
Y = (int)signatureFieldPosition.position.Top,
IsSigned = isSigned
};
}
private string GetFormFieldValueForName(PdfStamper stamper, string formFieldName)
{
AcroFields formFields = stamper.AcroFields;
return formFields.GetField(formFieldName);
}
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;
}
return null;
}
private byte[] SaveDocumentChanges(SaveRequest request, SigningInformation information)
{
request.Document = AddMetaData(information, request.Document);
request.Document = AddFormFields(request.FormFields, request.Document);
request.Document = AddSignatureFields(request.SigningBlocks, request.Document);
return request.Document;
}
private byte[] SignDocument(Certificate certificate, SigningInformation information, List<SigningBlock> signingBlocks, List<MemberItemSignature> signatureImages, byte[] document, bool isFinalSignature)
{
for (int i = 0; i < signingBlocks.Count; i++)
{
document = SignDocumentSignSignatureField(certificate, information, signingBlocks[i], signatureImages, document, true);
}
if (isFinalSignature)
{
return SignDocumentLTVVerification(certificate, document);
}
return document;
}
private byte[] SignDocumentLTVVerification(Certificate certificate, byte[] document)
{
using (MemoryStream outputStream = new MemoryStream())
{
using (PdfReader reader = new PdfReader(document))
{
using (PdfStamper stamper = PdfStamper.CreateSignature(reader, outputStream, ' ', null, true))
{
SignDocumentSigningBlockAddLTVVerification(stamper, certificate);
}
}
return outputStream.ToArray();
}
}
private void SignDocumentSigningBlock(SigningComponents components, SigningInformation information, SigningBlock block, PdfSignatureAppearance appearance, PdfStamper stamper, byte[] signatureImage)
{
appearance.SetVisibleSignature(block.Name);
SignDocumentSigningBlockWithImage(signatureImage, appearance);
SignDocumentSigningBlockWithText(appearance, information, appearance.SignDate);
if (components.Certificate != null)
{
using (RSACryptoServiceProvider rsa = (RSACryptoServiceProvider)components.Certificate.PrivateKey)
{
PrivateKeySignature privateKeySignature = SignDocumentSigningBlockBuildDigestSigningMethod(information, rsa) as PrivateKeySignature;
SignatureHelper.Sign(appearance, privateKeySignature, components.CertificateChain, new List<ICrlClient> { components.CrlClient }, components.OcspClient, components.TimeStampingAuthority, Int32.Parse(_settingManager["DocumentSigningEstimatedDigestSize"]), CryptoStandard.CMS, SignDocumentSigningBlockCreateMetaData(information));
}
}
else
{
HSMExternalSignature hsmExternalSignature = SignDocumentSigningBlockBuildDigestSigningMethod(information, null) as HSMExternalSignature;
SignatureHelper.Sign(appearance, hsmExternalSignature, components.TimeStampingAuthority, Int32.Parse(_settingManager["DocumentSigningEstimatedDigestSize"]), CryptoStandard.CMS, SignDocumentSigningBlockCreateMetaData(information));
}
}
private void SignDocumentSigningBlockAddLTVVerification(PdfStamper stamper, Certificate certificate)
{
SigningComponents components = new SigningComponents(_settingManager, certificate);
LtvVerification ltvVerification = stamper.LtvVerification;
List<string> signatureFieldNames = stamper.AcroFields.GetSignatureNames();
PdfPKCS7 pkcs7 = stamper.AcroFields.VerifySignature(signatureFieldNames.Last());
if (pkcs7.IsTsp)
{
bool validationAddedSuccessfully = ltvVerification.AddVerification(signatureFieldNames.Last(), components.OcspClient, components.CrlClient, LtvVerification.CertificateOption.SIGNING_CERTIFICATE, LtvVerification.Level.OCSP_CRL, LtvVerification.CertificateInclusion.YES);
}
else
{
foreach (string name in stamper.AcroFields.GetSignatureNames())
{
bool validationAddedSuccessfully = ltvVerification.AddVerification(name, components.OcspClient, components.CrlClient, LtvVerification.CertificateOption.WHOLE_CHAIN, LtvVerification.Level.OCSP_CRL, LtvVerification.CertificateInclusion.YES);
}
}
ltvVerification.Merge();
PdfSignatureAppearance appearance = stamper.SignatureAppearance;
LtvTimestamp.Timestamp(appearance, components.TimeStampingAuthority, null);
}
private IExternalSignature SignDocumentSigningBlockBuildDigestSigningMethod(SigningInformation information, RSACryptoServiceProvider rsaCryptoProvider)
{
if (information.CertificateUse == CertificateUse.SignisureCertificate || rsaCryptoProvider == null)
{
return new HSMExternalSignature(_hsmService, _settingManager["DocumentSigningEncryptionHashAlgorithm"]);
}
else
{
return new PrivateKeySignature(DotNetUtilities.GetRsaKeyPair(rsaCryptoProvider).Private, _settingManager["DocumentSigningEncryptionHashAlgorithm"]);
}
}
private PdfDictionary SignDocumentSigningBlockCreateMetaData(SigningInformation information)
{
PdfDictionary signatureDictionary = new PdfDictionary();
if (!String.IsNullOrWhiteSpace(information.IdentificationInformation))
{
AddMetaDataAddDictionaryValue(signatureDictionary, new PdfName(".Signisure.IdentificationInformation"), new PdfString(information.IdentificationInformation));
}
if (!String.IsNullOrWhiteSpace(information.JuristicEntity))
{
AddMetaDataAddDictionaryValue(signatureDictionary, new PdfName(".Signisure.JuristicEntity"), new PdfString(information.JuristicEntity));
}
if (!String.IsNullOrWhiteSpace(information.Capacity))
{
AddMetaDataAddDictionaryValue(signatureDictionary, new PdfName(".Signisure.Capacity"), new PdfString(information.Capacity));
}
return signatureDictionary;
}
private void SignDocumentSigningBlockWithImage(byte[] signatureImage, PdfSignatureAppearance appearance)
{
if (signatureImage != null && signatureImage.Length > 0)
{
Image signatureImageInstance = Image.GetInstance(ImageHelper.FlattenImage(signatureImage));
appearance.Image = signatureImageInstance;
appearance.SignatureGraphic = signatureImageInstance;
}
}
private void SignDocumentSigningBlockWithText(PdfSignatureAppearance appearance, SigningInformation information, DateTime timestampDateTime)
{
BaseFont verdana = BaseFont.CreateFont(AssemblyDirectory + "\Content\Fonts\Verdana\Verdana.ttf", BaseFont.CP1252, BaseFont.EMBEDDED);
BaseFont helvetica = BaseFont.CreateFont(AssemblyDirectory + "\Content\Fonts\Helvetica\Helvetica.ttf", BaseFont.CP1252, BaseFont.EMBEDDED);
BaseFont comicSans = BaseFont.CreateFont(AssemblyDirectory + "\Content\Fonts\ComicSans\ComicSans.ttf", BaseFont.CP1252, BaseFont.EMBEDDED);
appearance.Layer2Text = SignDocumentSigningBlockWithTextBuildText(appearance, information, timestampDateTime);
appearance.Layer2Font = new Font(verdana);
}
private string SignDocumentSigningBlockWithTextBuildText(PdfSignatureAppearance appearance, SigningInformation information, DateTime timestampDateTime)
{
return String.Format("Signee: {0}nSign date: {1}nLocation: {2}nReason: {3}", information.Signatory, timestampDateTime.ToLocalTime().ToString("yyyy-MM-dd HH:mm:ss zzz"), appearance.Location, appearance.Reason);
}
private byte[] SignDocumentSignSignatureField(Certificate certificate, SigningInformation information, SigningBlock signingBlock, List<MemberItemSignature> signatureImages, byte[] document, bool isVisible)
{
SigningComponents components = new SigningComponents(_settingManager, certificate);
using (MemoryStream outputStream = new MemoryStream())
{
using (PdfReader reader = new PdfReader(document))
{
using (PdfStamper stamper = CreatePdfStamper(reader, outputStream, true))
{
PdfSignatureAppearance appearance = CreatePdfAppearance(stamper, information, SignDocumentSignSignatureFieldBuildLocation(stamper, signingBlock), false);
SignDocumentSigningBlock(components, information, signingBlock, appearance, stamper, GetSignatureImage(signatureImages, signingBlock.Name));
}
}
return outputStream.ToArray();
}
}
private string SignDocumentSignSignatureFieldBuildLocation(PdfStamper stamper, SigningBlock signingBlock)
{
StringBuilder builder = new StringBuilder();
for (int index = 0; index < signingBlock.LinkedFormFields.Count; index++)
{
builder.Append(GetFormFieldValueForName(stamper, signingBlock.LinkedFormFields[index]));
if (index + 1 < signingBlock.LinkedFormFields.Count)
{
builder.Append(", ");
}
}
return builder.ToString();
}
private void UpdateFormField(PdfStamper stamper, FormField formField)
{
AcroFields formFields = stamper.AcroFields;
if (formField.Value != null && GetFormFieldValueForName(stamper, formField.Name) != formField.Value)
{
formFields.SetField(formField.Name, formField.Value);
formFields.SetFieldProperty(formField.Name, "setfflags", PdfFormField.FF_READ_ONLY, null);
}
}
}
}
简短回答：
如果使用级别为PdfSignatureAppearance.CERTIFIED_FORM_FILLING的证书签名对文档进行签名，则可以添加任意数量的额外批准签名，而不会破坏原始（或先前）签名。
更长的答案：
如果你写：，没有人会相信你
我正在尝试首先使用PdfSignatureAppearance.CERTIFIED_FORM_FILLING对文档进行签名，这将允许我添加更多签名字段、编辑表单字段或对其他签名字段进行签名，但这会使我随后的签名无效。
你在这里说的不对。
然而，也许您没有正确签署PDF。请允许我重复我的简短回答：
如果使用级别为 我强调两个概念。PDF最多可以有一个证书签名（也称为作者签名），该签名应为文档中的第一个签名PdfSignatureAppearance.CERTIFIED_FORM_FILLING的认证签名对文档进行签名，则可以添加任意数量的额外批准签名
也许您正在使用证书签名对文档进行签名（我认为这是真的，因为您谈论的是证书级别）。也许您正在尝试添加第二个证书签名。显然，这会破坏PDF中的签名，因为PDF规范只允许一个证书签名。
也许您的问题是通过添加批准签名而不是证书签名来解决的。