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Encryption bugfixing

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This commit is contained in:
Jakub Melka
2021-05-17 18:11:05 +02:00
parent 9539faf548
commit f070f0eb01
2 changed files with 37 additions and 19 deletions
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10
Pdf4QtLib/sources/pdfdocumentwriter.cpp
View File

@ -316,10 +316,16 @@ PDFOperationResult PDFDocumentWriter::write(QIODevice* device, const PDFDocument
device->write(entry.object.isNull() ? "f" : "n"); device->write(entry.object.isNull() ? "f" : "n");
writeCRLF(device); writeCRLF(device);
} }
// Jakub Melka: Adjust trailer dictionary, to be really dictionary, not a stream
PDFDictionary trailerDictionary = *document->getTrailerDictionary();
trailerDictionary.removeEntry("XRefStm");
PDFObject trailerDictionaryObject = PDFObject::createDictionary(std::make_shared<PDFDictionary>(qMove(trailerDictionary)));
device->write("trailer"); device->write("trailer");
writeCRLF(device); writeCRLF(device);
PDFWriteObjectVisitor trailerVisitor(device); PDFWriteObjectVisitor trailerVisitor(device);
storage.getTrailerDictionary().accept(&trailerVisitor); trailerDictionaryObject.accept(&trailerVisitor);
writeCRLF(device); writeCRLF(device);
device->write("startxref"); device->write("startxref");
writeCRLF(device); writeCRLF(device);
@ -339,7 +345,7 @@ void PDFDocumentWriter::writeCRLF(QIODevice* device)
void PDFDocumentWriter::writeObjectHeader(QIODevice* device, PDFObjectReference reference) void PDFDocumentWriter::writeObjectHeader(QIODevice* device, PDFObjectReference reference)
{ {
QString objectHeader = QString("%1 %2 obj").arg(QString::number(reference.objectNumber)).arg(QString::number(reference.generation)); QString objectHeader = QString("%1 %2 obj").arg(QString::number(reference.objectNumber), QString::number(reference.generation));
device->write(objectHeader.toLatin1()); device->write(objectHeader.toLatin1());
writeCRLF(device); writeCRLF(device);
} }

46
Pdf4QtLib/sources/pdfsecurityhandler.cpp
View File

@ -708,7 +708,6 @@ QByteArray PDFStandardSecurityHandler::decryptUsingFilter(const QByteArray& data
{ {
QByteArray initializationVector; QByteArray initializationVector;
QByteArray paddedData; QByteArray paddedData;
int paddingRemainder = 0;
}; };
auto prepareAES_data = [](const QByteArray& data) auto prepareAES_data = [](const QByteArray& data)
@ -726,18 +725,31 @@ QByteArray PDFStandardSecurityHandler::decryptUsingFilter(const QByteArray& data
result.paddedData = data.mid(AES_BLOCK_SIZE); result.paddedData = data.mid(AES_BLOCK_SIZE);
// Add padding remainder according to the specification // Remove errorneous data - we must have a data of multiple of AES_BLOCK_SIZE
int size = result.paddedData.size(); const int remainder = result.paddedData.size() % AES_BLOCK_SIZE;
result.paddingRemainder = AES_BLOCK_SIZE - (size % AES_BLOCK_SIZE); if (remainder != 0)
for (int i = 0; i < result.paddingRemainder; ++i)
{ {
result.paddedData.push_back(result.paddingRemainder); result.paddedData = result.paddedData.left(result.paddedData.size() - remainder);
} }
return result; return result;
}; };
auto removeAES_padding = [](const QByteArray& data)
{
if (data.isEmpty())
{
return data;
}
// If padding doesnt fit from 1 to AES_BLOCK_SIZE, then it is
// an error, but just clamp the value.
const int padding = data.back();
const int clampedPadding = qBound(1, padding, AES_BLOCK_SIZE);
return data.left(data.size() - clampedPadding);
};
switch (filter.type) switch (filter.type)
{ {
case CryptFilterType::None: // The application shall decrypt the data using the security handler case CryptFilterType::None: // The application shall decrypt the data using the security handler
@ -774,7 +786,7 @@ QByteArray PDFStandardSecurityHandler::decryptUsingFilter(const QByteArray& data
{ {
decryptedData.resize(aes_data.paddedData.size()); decryptedData.resize(aes_data.paddedData.size());
AES_cbc_encrypt(convertByteArrayToUcharPtr(aes_data.paddedData), convertByteArrayToUcharPtr(decryptedData), aes_data.paddedData.length(), &key, convertByteArrayToUcharPtr(aes_data.initializationVector), AES_DECRYPT); AES_cbc_encrypt(convertByteArrayToUcharPtr(aes_data.paddedData), convertByteArrayToUcharPtr(decryptedData), aes_data.paddedData.length(), &key, convertByteArrayToUcharPtr(aes_data.initializationVector), AES_DECRYPT);
decryptedData = decryptedData.left(data.length() - aes_data.paddingRemainder); decryptedData = removeAES_padding(decryptedData);
} }
break; break;
@ -791,7 +803,7 @@ QByteArray PDFStandardSecurityHandler::decryptUsingFilter(const QByteArray& data
{ {
decryptedData.resize(aes_data.paddedData.size()); decryptedData.resize(aes_data.paddedData.size());
AES_cbc_encrypt(convertByteArrayToUcharPtr(aes_data.paddedData), convertByteArrayToUcharPtr(decryptedData), aes_data.paddedData.length(), &key, convertByteArrayToUcharPtr(aes_data.initializationVector), AES_DECRYPT); AES_cbc_encrypt(convertByteArrayToUcharPtr(aes_data.paddedData), convertByteArrayToUcharPtr(decryptedData), aes_data.paddedData.length(), &key, convertByteArrayToUcharPtr(aes_data.initializationVector), AES_DECRYPT);
decryptedData = decryptedData.left(data.length() - aes_data.paddingRemainder); decryptedData = removeAES_padding(decryptedData);
} }
break; break;
@ -817,7 +829,6 @@ QByteArray PDFStandardSecurityHandler::encryptUsingFilter(const QByteArray& data
{ {
QByteArray initializationVector; QByteArray initializationVector;
QByteArray paddedData; QByteArray paddedData;
int paddingRemainder = 0;
}; };
auto prepareAES_data = [](const QByteArray& data) auto prepareAES_data = [](const QByteArray& data)
@ -836,11 +847,12 @@ QByteArray PDFStandardSecurityHandler::encryptUsingFilter(const QByteArray& data
// Add padding remainder according to the specification // Add padding remainder according to the specification
int size = data.size(); int size = data.size();
result.paddingRemainder = AES_BLOCK_SIZE - (size % AES_BLOCK_SIZE); const int paddingRemainder = AES_BLOCK_SIZE - (size % AES_BLOCK_SIZE);
for (int i = 0; i < result.paddingRemainder; ++i) result.initializationVector.reserve(result.initializationVector.size() + paddingRemainder);
for (int i = 0; i < paddingRemainder; ++i)
{ {
result.paddedData.push_back(result.paddingRemainder); result.paddedData.push_back(paddingRemainder);
} }
return result; return result;
@ -881,10 +893,10 @@ QByteArray PDFStandardSecurityHandler::encryptUsingFilter(const QByteArray& data
AES_data aes_data = prepareAES_data(data); AES_data aes_data = prepareAES_data(data);
if (!aes_data.paddedData.isEmpty()) if (!aes_data.paddedData.isEmpty())
{ {
QByteArray initializationVectorCopy = aes_data.initializationVector;
encryptedData.resize(aes_data.paddedData.size()); encryptedData.resize(aes_data.paddedData.size());
AES_cbc_encrypt(convertByteArrayToUcharPtr(aes_data.paddedData), convertByteArrayToUcharPtr(encryptedData), aes_data.paddedData.length(), &key, convertByteArrayToUcharPtr(aes_data.initializationVector), AES_ENCRYPT); AES_cbc_encrypt(convertByteArrayToUcharPtr(aes_data.paddedData), convertByteArrayToUcharPtr(encryptedData), aes_data.paddedData.length(), &key, convertByteArrayToUcharPtr(aes_data.initializationVector), AES_ENCRYPT);
encryptedData = encryptedData.left(data.length() - aes_data.paddingRemainder); encryptedData.prepend(initializationVectorCopy);
encryptedData.prepend(aes_data.initializationVector);
} }
break; break;
@ -899,10 +911,10 @@ QByteArray PDFStandardSecurityHandler::encryptUsingFilter(const QByteArray& data
AES_data aes_data = prepareAES_data(data); AES_data aes_data = prepareAES_data(data);
if (!aes_data.paddedData.isEmpty()) if (!aes_data.paddedData.isEmpty())
{ {
QByteArray initializationVectorCopy = aes_data.initializationVector;
encryptedData.resize(aes_data.paddedData.size()); encryptedData.resize(aes_data.paddedData.size());
AES_cbc_encrypt(convertByteArrayToUcharPtr(aes_data.paddedData), convertByteArrayToUcharPtr(encryptedData), aes_data.paddedData.length(), &key, convertByteArrayToUcharPtr(aes_data.initializationVector), AES_ENCRYPT); AES_cbc_encrypt(convertByteArrayToUcharPtr(aes_data.paddedData), convertByteArrayToUcharPtr(encryptedData), aes_data.paddedData.length(), &key, convertByteArrayToUcharPtr(aes_data.initializationVector), AES_ENCRYPT);
encryptedData = encryptedData.left(data.length() - aes_data.paddingRemainder); encryptedData.prepend(initializationVectorCopy);
encryptedData.prepend(aes_data.initializationVector);
} }
break; break;