MOUNTAIN VIEW, Calif. (AP) — 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 allowing users to talk and text in private, said a series of disclosures from former intelligence contractor Edward Snowden last year have been a boon for business.