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check checksum when getting e2ee metadata

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Signed-off-by: Matthieu Gallien <matthieu.gallien@nextcloud.com>
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Matthieu Gallien 2023-03-28 00:45:28 +02:00
parent 1b0a93eabc
commit 1b14c127a4
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2 changed files with 36 additions and 13 deletions
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45
src/libsync/clientsideencryption.cpp
View file

@ -33,6 +33,7 @@
#include <QUuid>
#include <QScopeGuard>
#include <QRandomGenerator>
#include <QCryptographicHash>
#include <qt5keychain/keychain.h>
#include <common/utility.h>
@ -1555,10 +1556,10 @@ void FolderMetadata::setupExistingMetadata(const QByteArray& metadata)
}
}
if (_metadataKey.isEmpty()) {
qCDebug(lcCse()) << "Could not setup existing metadata with missing metadataKeys!";
return;
}
const auto sharing = metadataObj["sharing"].toString().toLocal8Bit();
const auto files = metaDataDoc.object()["files"].toObject();
const auto metadataKey = metaDataDoc.object()["metadata"].toObject()["metadataKey"].toString().toUtf8();
const auto metadataKeyChecksum = metaDataDoc.object()["metadata"].toObject()["checksum"].toString().toUtf8();
QByteArray sharing = metadataObj["sharing"].toString().toLocal8Bit();
QJsonObject files = metaDataDoc.object()["files"].toObject();
@ -1609,17 +1610,15 @@ void FolderMetadata::setupExistingMetadata(const QByteArray& metadata)
file.encryptionKey = QByteArray::fromBase64(decryptedFileObj["key"].toString().toLocal8Bit());
file.mimetype = decryptedFileObj["mimetype"].toString().toLocal8Bit();
// In case we wrongly stored "inode/directory" we try to recover from it
if (file.mimetype == QByteArrayLiteral("inode/directory")) {
file.mimetype = QByteArrayLiteral("httpd/unix-directory");
if (!checkMetadataKeyChecksum(metadataKey, metadataKeyChecksum)) {
_metadataKey.clear();
_files.clear();
return;
}
_files.push_back(file);
}
// decryption finished, create new metadata key to be used for encryption
_metadataKey = EncryptionHelper::generateRandom(metadataKeySize);
_isMetadataSetup = true;
// decryption finished, create new metadata key to be used for encryption
_metadataKey = EncryptionHelper::generateRandom(metadataKeySize);
_isMetadataSetup = true;
}
// RSA/ECB/OAEPWithSHA-256AndMGF1Padding using private / public key.
@ -1663,6 +1662,26 @@ QByteArray FolderMetadata::decryptJsonObject(const QByteArray& encryptedMetadata
return EncryptionHelper::decryptStringSymmetric(pass, encryptedMetadata);
}
bool FolderMetadata::checkMetadataKeyChecksum(const QByteArray &metadataKey,
const QByteArray &metadataKeyChecksum) const
{
const auto referenceMetadataKeyValue = computeMetadataKeyChecksum(metadataKey);
return referenceMetadataKeyValue == metadataKeyChecksum;
}
QByteArray FolderMetadata::computeMetadataKeyChecksum(const QByteArray &metadataKey) const
{
auto checksumData = _account->e2e()->_mnemonic.remove(' ');
for (const auto &singleFile : _files) {
checksumData += singleFile.encryptedFilename;
}
checksumData += metadataKey;
auto hashAlgorithm = QCryptographicHash{QCryptographicHash::Sha256};
hashAlgorithm.addData(checksumData.toUtf8());
return hashAlgorithm.result().toHex();
}
bool FolderMetadata::isMetadataSetup() const
{
return _isMetadataSetup;

4
src/libsync/clientsideencryption.h
View file

@ -213,6 +213,10 @@ private:
[[nodiscard]] QByteArray encryptJsonObject(const QByteArray& obj, const QByteArray pass) const;
[[nodiscard]] QByteArray decryptJsonObject(const QByteArray& encryptedJsonBlob, const QByteArray& pass) const;
[[nodiscard]] bool checkMetadataKeyChecksum(const QByteArray &metadataKey, const QByteArray &metadataKeyChecksum) const;
[[nodiscard]] QByteArray computeMetadataKeyChecksum(const QByteArray &metadataKey) const;
QByteArray _metadataKey;
QVector<EncryptedFile> _files;