Strange padlock icon on status bar (not rotation-lock!)
This icon does not appear in any of the devices running iOS 7 or 8. 

It's probably caused by a jailbreak tweak. OpenNotifier is one such jailbreak tweak which lets you customise the status bar to indicate notifications from any app. The icon does not seem to relate to anything specific so it's quite impossible to tell what's it's indicating. Checking the tweak settings could tell what's that icon is indicating.