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Encryption bugfixing (AES 256)

This commit is contained in:
Jakub Melka 2021-05-31 11:09:07 +02:00
parent e001adc65b
commit ea555fe540
1 changed files with 11 additions and 8 deletions
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19
Pdf4QtLib/sources/pdfsecurityhandler.cpp
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@ -515,7 +515,7 @@ void PDFSecurityHandler::fillEncryptionDictionary(PDFObjectFactory& factory) con
factory << PDFInteger(m_V); factory << PDFInteger(m_V);
factory.endDictionaryItem(); factory.endDictionaryItem();
if (m_V == 2 || m_V == 3) if (m_V == 2 || m_V == 3 || m_V == 4)
{ {
factory.beginDictionaryItem("Length"); factory.beginDictionaryItem("Length");
factory << PDFInteger(m_keyLength); factory << PDFInteger(m_keyLength);
@ -1171,7 +1171,7 @@ PDFObject PDFStandardSecurityHandler::createEncryptionDictionaryObject() const
} }
factory.beginDictionaryItem("P"); factory.beginDictionaryItem("P");
factory << PDFInteger(m_permissions); factory << PDFInteger(int32_t(m_permissions));
factory.endDictionaryItem(); factory.endDictionaryItem();
if (m_R == 6) if (m_R == 6)
@ -1219,7 +1219,7 @@ QByteArray PDFStandardSecurityHandler::createFileEncryptionKey(const QByteArray&
MD5_Update(&context, &value, sizeof(value)); MD5_Update(&context, &value, sizeof(value));
} }
std::array<uint8_t, MD5_DIGEST_LENGTH> fileEncryptionKey; std::array<uint8_t, MD5_DIGEST_LENGTH> fileEncryptionKey = { };
MD5_Final(fileEncryptionKey.data(), &context); MD5_Final(fileEncryptionKey.data(), &context);
const int keyByteLength = m_keyLength / 8; const int keyByteLength = m_keyLength / 8;
@ -1280,7 +1280,7 @@ QByteArray PDFStandardSecurityHandler::createEntryValueU_r234(const QByteArray&
case 3: case 3:
case 4: case 4:
{ {
std::array<uint8_t, MD5_DIGEST_LENGTH> hash; std::array<uint8_t, MD5_DIGEST_LENGTH> hash = { };
MD5_CTX context = { }; MD5_CTX context = { };
MD5_Init(&context); MD5_Init(&context);
@ -1291,7 +1291,8 @@ QByteArray PDFStandardSecurityHandler::createEntryValueU_r234(const QByteArray&
RC4_KEY key = { }; RC4_KEY key = { };
RC4_set_key(&key, fileEncryptionKey.size(), convertByteArrayToUcharPtr(fileEncryptionKey)); RC4_set_key(&key, fileEncryptionKey.size(), convertByteArrayToUcharPtr(fileEncryptionKey));
std::array<uint8_t, MD5_DIGEST_LENGTH> encryptedHash; std::array<uint8_t, MD5_DIGEST_LENGTH> encryptedHash = { };
std::array<uint8_t, MD5_DIGEST_LENGTH> targetBuffer = { };
RC4(&key, hash.size(), hash.data(), encryptedHash.data()); RC4(&key, hash.size(), hash.data(), encryptedHash.data());
QByteArray transformedKey = fileEncryptionKey; QByteArray transformedKey = fileEncryptionKey;
@ -1303,7 +1304,8 @@ QByteArray PDFStandardSecurityHandler::createEntryValueU_r234(const QByteArray&
} }
RC4_set_key(&key, transformedKey.size(), convertByteArrayToUcharPtr(transformedKey)); RC4_set_key(&key, transformedKey.size(), convertByteArrayToUcharPtr(transformedKey));
RC4(&key, encryptedHash.size(), encryptedHash.data(), encryptedHash.data()); RC4(&key, encryptedHash.size(), encryptedHash.data(), targetBuffer.data());
encryptedHash = targetBuffer;
} }
// We do a hack here. In the PDF's specification, it is written, that arbitrary 16 bytes // We do a hack here. In the PDF's specification, it is written, that arbitrary 16 bytes
@ -1311,6 +1313,7 @@ QByteArray PDFStandardSecurityHandler::createEntryValueU_r234(const QByteArray&
// want to compare byte arrays entirely (otherwise we must compare only 16 bytes to authenticate // want to compare byte arrays entirely (otherwise we must compare only 16 bytes to authenticate
// user password). // user password).
result = m_U; result = m_U;
result.detach();
if (result.size() != 32) if (result.size() != 32)
{ {
@ -1772,9 +1775,9 @@ PDFSecurityHandlerPointer PDFSecurityHandlerFactory::createSecurityHandler(const
break; break;
} }
handler->m_cryptFilters["DefaultCF"] = handler->m_filterDefault; handler->m_cryptFilters["StdCF"] = handler->m_filterDefault;
handler->m_R = getRevisionFromAlgorithm(settings.algorithm); handler->m_R = getRevisionFromAlgorithm(settings.algorithm);
handler->m_permissions = settings.permissions; handler->m_permissions = settings.permissions | 0xFFFFF000;
QByteArray adjustedOwnerPassword = handler->adjustPassword(settings.ownerPassword, handler->m_R); QByteArray adjustedOwnerPassword = handler->adjustPassword(settings.ownerPassword, handler->m_R);
QByteArray adjustedUserPassword = handler->adjustPassword(settings.userPassword, handler->m_R); QByteArray adjustedUserPassword = handler->adjustPassword(settings.userPassword, handler->m_R);