I instinctively believe that encryption back doors are a bad idea. This article articulates a thought experiment that demonstrates its futility.
You Can’t Backdoor a Platform According to law enforcement and intelligence agencies, encryption should come with a backdoor. It’s not a new policy position—it dates to the Crypto Wars of the 1990s—but it’s gaining new Beltway currency. Cryptographic backdoors are a bad idea. They introduce unquantifiable security risks, like the recent FREAK vulnerability. They could equip oppressive governments, not just the United States. They chill free speech. They impose costs on innovators and reduce foreign demand for American products. The list of objections runs long.
http://webpolicy.org/2015/04/28/you-cant-backdoor-a-platform/