Recently one of my conversational partners in a discussion about “security in Android” mentioned an article of “PC-Welt” which, amongst other things, also recommends “SRT AppGuard” as a tool to improve the security of apps (as of February 2013, also see http://www.pcwelt.de/ratgeber/Android-Sicherheit-erhoehen-App-Rechte-beschraenken-5842959.html – I already contacted the editoral staff, maybe this article was already changed or removed).
In short: You should not use SRT AppGuard and there are good reasons why this app was removed from the Google Play Store a while ago!
(Please see the German version for more details)