feat(database): use own public key as salt to encrypt the database

fixes #3583

BREAKING CHANGE:
The database will be encrypted with a new key, qTox versions before this
commit won't be able to decrypt the database.

src/persistence/db/rawdatabase.cpp

@@ -91,15 +91,43 @@
  * @param password If empty, the database will be opened unencrypted.
  * Otherwise we will use toxencryptsave to derive a key and encrypt the database.
  */
-RawDatabase::RawDatabase(const QString &path, const QString& password)
-    : workerThread{new QThread}, path{path}, currentHexKey{deriveKey(password)}
+RawDatabase::RawDatabase(const QString& path, const QString& password, const QByteArray& salt)
+    : workerThread{new QThread}
+    , path{path}
+    , currentSalt{salt}     // we need the salt later if a new password should be set
+    , currentHexKey{deriveKey(password, salt)}
 {
     workerThread->setObjectName("qTox Database");
     moveToThread(workerThread.get());
     workerThread->start();
 
-    if (!open(path, currentHexKey))
+    // first try with the new salt
+    if (open(path, currentHexKey))
+    {
         return;
+    }
+
+    // avoid opening the same db twice
+    close();
+
+    // fall back to the old salt
+    currentHexKey = deriveKey(password);
+    if(open(path, currentHexKey))
+    {
+        // still using old salt, upgrade
+        if(setPassword(password))
+        {
+            qDebug() << "Successfully upgraded to dynamic salt";
+        }
+        else
+        {
+            qWarning() << "Failed to set password with new salt";
+        }
+    }
+    else
+    {
+        qDebug() << "Failed to open database with old salt";
+    }
 }
 
 RawDatabase::~RawDatabase()
@@ -313,7 +341,7 @@ bool RawDatabase::setPassword(const QString& password)
 
     if (!password.isEmpty())
     {
-        QString newHexKey = deriveKey(password);
+        QString newHexKey = deriveKey(password, currentSalt);
         if (!currentHexKey.isEmpty())
         {
             if (!execNow("PRAGMA rekey = \"x'"+newHexKey+"'\""))
@@ -445,6 +473,7 @@ bool RawDatabase::remove()
  * @brief Derives a 256bit key from the password and returns it hex-encoded
  * @param password Password to decrypt database
  * @return String representation of key
+ * @deprecated deprecated on 2016-11-06, kept for compatibility, replaced by the salted version
  */
 QString RawDatabase::deriveKey(const QString &password)
 {
@@ -457,8 +486,37 @@ QString RawDatabase::deriveKey(const QString &password)
 
     static const uint8_t expandConstant[TOX_PASS_SALT_LENGTH+1] = "L'ignorance est le pire des maux";
     TOX_PASS_KEY key;
-    tox_derive_key_with_salt((uint8_t*)passData.data(), passData.size(), expandConstant, &key, nullptr);
-    return QByteArray((char*)key.key, 32).toHex();
+    tox_derive_key_with_salt(reinterpret_cast<uint8_t*>(passData.data()), static_cast<std::size_t>(passData.size()), expandConstant, &key, nullptr);
+    return QByteArray(reinterpret_cast<char*>(key.key), 32).toHex();
+}
+
+/**
+ * @brief Derives a 256bit key from the password and returns it hex-encoded
+ * @param password Password to decrypt database
+ * @param salt Salt to improve password strength, must be TOX_PASS_SALT_LENGTH bytes
+ * @return String representation of key
+ */
+QString RawDatabase::deriveKey(const QString& password, const QByteArray& salt)
+{
+    if (password.isEmpty())
+    {
+        return {};
+    }
+
+    if (salt.length() != TOX_PASS_SALT_LENGTH)
+    {
+        qWarning() << "Salt length doesn't match toxencryptsave expections";
+        return {};
+    }
+
+    QByteArray passData = password.toUtf8();
+
+    static_assert(TOX_PASS_KEY_LENGTH >= 32, "toxcore must provide 256bit or longer keys");
+
+    TOX_PASS_KEY key;
+    tox_derive_key_with_salt(reinterpret_cast<uint8_t*>(passData.data()), static_cast<std::size_t>(passData.size()),
+                             reinterpret_cast<const uint8_t*>(salt.constData()), &key, nullptr);
+    return QByteArray(reinterpret_cast<char*>(key.key), 32).toHex();
 }
 
 /**

src/persistence/db/rawdatabase.h

@@ -41,7 +41,7 @@ public:
     };
 
 public:
-    RawDatabase(const QString& path, const QString& password);
+    RawDatabase(const QString& path, const QString& password, const QByteArray& salt);
     ~RawDatabase();
     bool isOpen();
 
@@ -68,7 +68,8 @@ private:
     QString anonymizeQuery(const QByteArray& query);
 
 protected:
-    static QString deriveKey(const QString &password);
+    static QString deriveKey(const QString& password, const QByteArray& salt);
+    static QString deriveKey(const QString& password);
     static QVariant extractData(sqlite3_stmt* stmt, int col);
 
 private:
@@ -85,6 +86,7 @@ private:
     QQueue<Transaction> pendingTransactions;
     QMutex transactionsMutex;
     QString path;
+    QByteArray currentSalt;
     QString currentHexKey;
 };
 

src/persistence/profile.cpp

@@ -56,7 +56,6 @@ QVector<QString> Profile::profiles;
 
 Profile::Profile(QString name, const QString& password, bool isNewProfile)
     : name{name}, password{password}
-    , database(std::make_shared<RawDatabase>(getDbPath(name), password))
     , newProfile{isNewProfile}, isRemoved{false}
 {
     if (!password.isEmpty())
@@ -68,22 +67,10 @@ Profile::Profile(QString name, const QString& password, bool isNewProfile)
     s.setCurrentProfile(name);
     s.saveGlobal();
 
-    // At this point it's too early to load the personal settings (Nexus will do
-    // it), so we always load the history, and if it fails we can't change the
-    // setting now, but we keep a nullptr
-    if (database->isOpen())
-    {
-        history.reset(new History(database));
-    }
-    else
-    {
-        qWarning() << "Failed to open history for profile" << name;
-        GUI::showError(QObject::tr("Error"), QObject::tr("qTox couldn't open your chat logs, they will be disabled."));
-    }
-
     coreThread = new QThread();
     coreThread->setObjectName("qTox Core");
     core = new Core(coreThread, *this);
+    QObject::connect(core, &Core::idSet, this, &Profile::loadDatabase, Qt::QueuedConnection);
     core->moveToThread(coreThread);
     QObject::connect(coreThread, &QThread::started, core, &Core::start);
 }
@@ -512,6 +499,34 @@ QByteArray Profile::loadAvatarData(const QString& ownerId, const QString& passwo
     return pic;
 }
 
+void Profile::loadDatabase(const QString& id)
+{
+    if(isRemoved)
+    {
+        qDebug() << "Can't load database of removed profile";
+        return;
+    }
+
+    QByteArray salt = QByteArray::fromHex(ToxId {id}.publicKey.toUtf8());
+    if(salt.size() != TOX_PASS_SALT_LENGTH)
+    {
+        qWarning() << "Couldn't compute salt from public key" << name;
+        GUI::showError(QObject::tr("Error"), QObject::tr("qTox couldn't open your chat logs, they will be disabled."));
+    }
+    // At this point it's too early to load the personal settings (Nexus will do it), so we always load
+    // the history, and if it fails we can't change the setting now, but we keep a nullptr
+    database = std::make_shared<RawDatabase>(getDbPath(name), password, salt);
+    if (database && database->isOpen())
+    {
+        history.reset(new History(database));
+    }
+    else
+    {
+        qWarning() << "Failed to open database for profile" << name;
+        GUI::showError(QObject::tr("Error"), QObject::tr("qTox couldn't open your chat logs, they will be disabled."));
+    }
+}
+
 /**
  * @brief Save an avatar to cache.
  * @param pic Picture to save.
@@ -688,11 +703,12 @@ QVector<QString> Profile::remove()
     }
 
     QString dbPath = getDbPath(name);
-    if (database->isOpen() && !database->remove() && QFile::exists(dbPath))
+    if (database && database->isOpen() && !database->remove() && QFile::exists(dbPath))
     {
         ret.push_back(dbPath);
         qWarning() << "Could not remove file " << dbPath;
     }
+
     history.release();
     database.reset();
 

src/persistence/profile.h

@@ -25,6 +25,7 @@
 #include <QString>
 #include <QByteArray>
 #include <QPixmap>
+#include <QObject>
 #include <tox/toxencryptsave.h>
 #include <memory>
 #include "src/persistence/history.h"
@@ -32,8 +33,10 @@
 class Core;
 class QThread;
 
-class Profile
+class Profile : public QObject
 {
+    Q_OBJECT
+
 public:
     static Profile* loadProfile(QString name, const QString& password = QString());
     static Profile* createProfile(QString name, QString password);
@@ -78,6 +81,8 @@ public:
     static bool isEncrypted(QString name);
     static QString getDbPath(const QString& profileName);
 
+private slots:
+    void loadDatabase(const QString& id);
 private:
     Profile(QString name, const QString& password, bool newProfile);
     static QVector<QString> getFilesByExt(QString extension);