diff --git a/lib/lib_gnupg.sh b/lib/lib_gnupg.sh
index 21aaf11..381c716 100644
--- a/lib/lib_gnupg.sh
+++ b/lib/lib_gnupg.sh
@@ -112,8 +112,13 @@ EOF
 
     fi
 
-    shred -fzu -n 5 -- "${VAR_TMP_SECRET}/${VAR_SIGNING_KEY}"
-    shred -fzu -n 5 -- "${VAR_TMP_SECRET}/${VAR_SIGNING_CA}"
+    if [[ -n "${VAR_SIGNING_KEY}" ]]; then
+      shred -fzu -n 5 -- "${VAR_TMP_SECRET}/${VAR_SIGNING_KEY}"
+    fi
+
+    if [[ -n "${VAR_SIGNING_KEY}" ]]; then
+      shred -fzu -n 5 -- "${VAR_TMP_SECRET}/${VAR_SIGNING_CA}"
+    fi
 
     ### Export public key for verification inside ISO / chroot.
     install -d -m 0755 -o root -g root "${VAR_HANDLER_BUILD_DIR}/config/includes.chroot/etc/ciss/keys"