In this photo taken Wednesday, July 30, 2014, Silicon Valley pioneer and Silent Circle co-founder Jon Callas holds up Blackphone with encryption apps displayed on it at the Computer History Museum in Mountain View, Calif.
Revelations about the National Security Agency's electronic eavesdropping capabilities have sparked anger in Germany and a boom in encryption services that make it hard for the most sophisticated spies to read emails, listen to calls or comb through texts.
Jon Callas, co-founder of Silent Circle, which sells an encryption app that allows users to talk and text in private, says a series of disclosures from former intelligence contractor Edward Snowden last year have been a real boon for business.
Silent Circle is one of a host of online security companies pitching products to security-conscious customers around the world who want to shield their communications from foreign governments - and nowhere is the market hotter than in Germany. Eavesdropping targets have reportedly included German Chancellor Angela Merkel.