diff --git a/src/core/engine.cpp b/src/core/engine.cpp
--- a/src/core/engine.cpp
+++ b/src/core/engine.cpp
@@ -95,9 +95,6 @@
     connect(m_searchTimer, &QTimer::timeout, this, &Engine::slotSearchTimerExpired);
     connect(m_installation, &Installation::signalInstallationFinished, this, &Engine::slotInstallationFinished);
     connect(m_installation, &Installation::signalInstallationFailed, this, &Engine::slotInstallationFailed);
-    connect(m_installation, &Installation::signalInformation, this, &Engine::signalMessage);
-    connect(m_installation, &Installation::signalError, this, &Engine::signalError);
-
 }
 
 Engine::~Engine()
diff --git a/src/core/installation.h b/src/core/installation.h
--- a/src/core/installation.h
+++ b/src/core/installation.h
@@ -116,7 +116,9 @@
      */
     void uninstall(KNSCore::EntryInternal entry);
 
-    void slotInstallationVerification(int result);
+    // TODO KF6: remove, was used with deprecated Security class.
+    Q_DECL_DEPRECATED void slotInstallationVerification(int result);
+
     void slotPayloadResult(KJob *job);
 
 Q_SIGNALS:
@@ -126,8 +128,9 @@
 
     void signalPayloadLoaded(QUrl payload); // FIXME: return Entry
 
-    void signalInformation(const QString &) const;
-    void signalError(const QString &) const;
+    // TODO KF6: remove, was used with deprecated Security class.
+    Q_DECL_DEPRECATED void signalInformation(const QString &) const;
+    Q_DECL_DEPRECATED void signalError(const QString &) const;
 
 private:
     void install(KNSCore::EntryInternal entry, const QString &downloadedFile);
diff --git a/src/core/installation.cpp b/src/core/installation.cpp
--- a/src/core/installation.cpp
+++ b/src/core/installation.cpp
@@ -38,7 +38,6 @@
 #include <knewstuffcore_debug.h>
 
 #include "jobs/filecopyjob.h"
-#include "security.h"
 #include "question.h"
 #ifdef Q_OS_WIN
 #include <windows.h>
@@ -55,17 +54,6 @@
     , customName(false)
     , acceptHtml(false)
 {
-    Security *sec = Security::ref();
-
-    connect(sec,
-            &Security::validityResult,
-            this, &Installation::slotInstallationVerification);
-    connect(sec,
-            &Security::signalInformation,
-            this, &Installation::signalInformation);
-    connect(sec,
-            &Security::signalError,
-            this, &Installation::signalError);
 }
 
 bool Installation::readConfig(const KConfigGroup &group)
@@ -277,7 +265,6 @@
         return;
     }
 
-    // FIXME: first of all, do the security stuff here
     // this means check sum comparison and signature verification
     // signature verification might take a long time - make async?!
     /*
@@ -322,13 +309,6 @@
     }
 
     entry.setInstalledFiles(installedFiles);
-    // ==== FIXME: security code below must go above, when async handling is complete ====
-
-    // FIXME: security object lifecycle - it is a singleton!
-    Security *sec = Security::ref();
-
-    // FIXME: change to accept filename + signature
-    sec->checkValidity(QString());
 
     auto installationFinished = [this, entry]() {
         EntryInternal newentry = entry;
@@ -648,16 +628,7 @@
 
 void Installation::slotInstallationVerification(int result)
 {
-    qCDebug(KNEWSTUFFCORE) << "SECURITY result " << result;
-
-    //FIXME do something here ??? and get the right entry again
-    EntryInternal entry;
-
-    if (result & Security::SIGNED_OK) {
-        emit signalEntryChanged(entry);
-    } else {
-        emit signalEntryChanged(entry);
-    }
+    // Deprecated, was wired up to defunct Security class.
 }
 
 QStringList Installation::archiveEntries(const QString &path, const KArchiveDirectory *dir)
diff --git a/src/core/security.h b/src/core/security.h
--- a/src/core/security.h
+++ b/src/core/security.h
@@ -38,14 +38,11 @@
 {
 
 /**
-Handles security related issues, like signing, verifying.
-It is a private class, not meant to be used by third party applications.
-
-@author Andras Mantia <amantia@kde.org>
-
-* @internal
+ * Do not use this class. It is non-functional and internal.
+ * @internal
+ * @deprecated
 */
-class KNEWSTUFFCORE_EXPORT Security : public QObject
+class Q_DECL_DEPRECATED KNEWSTUFFCORE_EXPORT Security : public QObject
 {
     Q_OBJECT
 public: