diff --git a/activation.hpp b/activation.hpp
index ba7c618..7f0120f 100644
--- a/activation.hpp
+++ b/activation.hpp
@@ -8,6 +8,12 @@
 #include "xyz/openbmc_project/Software/ActivationProgress/server.hpp"
 #include "org/openbmc/Associations/server.hpp"
 
+#include "config.h"
+
+#ifdef WANT_SIGNATURE_VERIFY
+#include <experimental/filesystem>
+#endif
+
 namespace phosphor
 {
 namespace software
@@ -15,6 +21,10 @@
 namespace updater
 {
 
+#ifdef WANT_SIGNATURE_VERIFY
+namespace fs = std::experimental::filesystem;
+#endif
+
 using AssociationList =
     std::vector<std::tuple<std::string, std::string, std::string>>;
 using ActivationInherit = sdbusplus::server::object::object<
@@ -320,6 +330,21 @@
     /** @brief Tracks if the service that updates the U-Boot environment
      *         variables has completed. **/
     bool ubootEnvVarsUpdated = false;
+
+#ifdef WANT_SIGNATURE_VERIFY
+  private:
+    /** @brief Verify signature of the images.
+     *
+     * @param[in] imageDir - The path of images to verify
+     * @param[in] confDir - The path of configs for verification
+     *
+     * @return true if verification successful and false otherwise
+     */
+    bool verifySignature(const fs::path& imageDir, const fs::path& confDir);
+
+    /** @brief Called when image verification fails. */
+    void onVerifyFailed();
+#endif
 };
 
 } // namespace updater