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Signature plugin: digital signing

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Jakub Melka
2022-05-22 17:17:06 +02:00
parent aebed28c6d
commit 3d6954dc41
4 changed files with 241 additions and 53 deletions
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76
Pdf4QtViewerPlugins/SignaturePlugin/signatureplugin.cpp
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@ -23,6 +23,7 @@
#include "pdfdocumentbuilder.h"
#include "certificatemanagerdialog.h"
#include "signdialog.h"
#include "pdfdocumentwriter.h"
#include <QAction>
#include <QToolButton>
@ -325,16 +326,77 @@ void SignaturePlugin::onSignDigitally()
SignDialog dialog(m_dataExchangeInterface->getMainWindow(), m_scene.isEmpty());
if (dialog.exec() == SignDialog::Accepted)
{
QByteArray data = "xxgaghre";
QByteArray result;
SignatureFactory::sign(dialog.getCertificatePath(), dialog.getPassword(), data, result);
for (int i = 1; i < 15; ++i)
QByteArray data = "SampleDataToBeSigned" + QByteArray::number(QDateTime::currentMSecsSinceEpoch());
QByteArray signature;
if (!SignatureFactory::sign(dialog.getCertificatePath(), dialog.getPassword(), data, signature))
{
data.append(data);
QMessageBox::critical(m_widget, tr("Error"), tr("Failed to create digital signature."));
return;
}
SignatureFactory::sign(dialog.getCertificatePath(), dialog.getPassword(), data, result);
pdf::PDFInteger offsetMark = 123456789123;
constexpr const char* offsetMarkString = "123456789123";
const auto offsetMarkStringLength = std::strlen(offsetMarkString);
pdf::PDFDocumentBuilder builder(m_document);
pdf::PDFObjectReference signatureDictionary = builder.createSignatureDictionary("Adobe.PPKLite", "adbe.pkcs7.detached", signature, QDateTime::currentDateTime(), offsetMark);
pdf::PDFObjectReference formField = builder.createFormFieldSignature("signature", { }, signatureDictionary);
builder.createAcroForm({ formField });
pdf::PDFDocument signedDocument = builder.build();
// 1) Save the document with incorrect signature
QBuffer buffer;
pdf::PDFDocumentWriter writer(m_widget->getDrawWidgetProxy()->getProgress());
buffer.open(QBuffer::ReadWrite);
writer.write(&buffer, &signedDocument);
const int indexOfSignature = buffer.data().indexOf(signature.toHex());
if (indexOfSignature == -1)
{
QMessageBox::critical(m_widget, tr("Error"), tr("Failed to create digital signature."));
buffer.close();
return;
}
// 2) Write ranges to be checked
const pdf::PDFInteger i1 = 0;
const pdf::PDFInteger i2 = indexOfSignature;
const pdf::PDFInteger i3 = i2 + signature.size() * 2;
const pdf::PDFInteger i4 = buffer.data().size() - i3;
auto writeInt = [&](pdf::PDFInteger offset)
{
QString offsetString = QString::number(offset);
offsetString = offsetString.leftJustified(static_cast<int>(offsetMarkStringLength), ' ', true);
const auto index = buffer.data().lastIndexOf(QString(offsetMarkString), indexOfSignature);
buffer.seek(index);
buffer.write(offsetString.toLocal8Bit());
};
writeInt(i4);
writeInt(i3);
writeInt(i2);
writeInt(i1);
// 3) Sign the data
QByteArray dataToBeSigned;
buffer.seek(i1);
dataToBeSigned.append(buffer.read(i2));
buffer.seek(i3);
dataToBeSigned.append(buffer.read(i4));
if (!SignatureFactory::sign(dialog.getCertificatePath(), dialog.getPassword(), dataToBeSigned, signature))
{
QMessageBox::critical(m_widget, tr("Error"), tr("Failed to create digital signature."));
buffer.close();
return;
}
buffer.seek(i2);
buffer.write(signature.toHex());
buffer.close();
}
}