A security researcher has created an app that allows you to log an iPad user’s keystrokes from any distance, so long as you’ve got a line of sight to the device’s keyboard.

Researcher Haroon Meer of security firm Thinkst in South Africa’s Pretoria announced the app, shoulderPad, earlier this week, Forbes’ Andy Greenberg reports.

The app, which can be installed on Mac OS and jailbroken iPhones and iPads, uses image recognition software to identify each keystroke an iPad user makes. As a form of feedback, the iPad’s virtual keyboard flashes blue when you hit a key to confirm that you pressed the right one. It’s this blue flash that allows the app to decode keystrokes automatically.

The same technology could be used on recorded surveillance camera footage to get the same results, Meer told Forbes.

This development is bound to provoke some discussions at Apple, and I know I’ll be more careful about punching in a password in public — even if it is unlikely there’s someone watching with shoulderPad.