GCHQ and NSA Collaborate to Steal the Keys to Your CellphoneNadia Kayyali In other words, for millions or even billions of users around the world, global cellular communications are about as secure from GCHQ and NSA as an FM radio broadcast. Heres how it works. As The Intercept explains: The privacy of all mobile communications voice calls, text messages and Internet access depends on an encrypted connection between the cellphone and the wireless carriers network, using keys stored on the SIM, a tiny chip smaller than a postage stamp, which is inserted into the phone. All mobile communications on the phone depend on the SIM, which stores and guards the encryption keys created by companies like Gemalto. So, under normal circumstances, when a mobile call, text, or other communication is made, that communication is encrypted as it travels through the air from a mobile device to a carriers tower. At that point, even if the communication was intercepted by a third party (like the NSA or Iran or the local mafia), it would be encrypted and (generally speaking) indecipherable. But anyone who has obtained the encryption key (known as a Ki) for a particular wireless user could use it to decrypt that communication. To make matters worse, because of how Kis operate, any previously obtained encrypted communications can be decrypted later once anyone obtains the correct Ki. As the Intercept notes, if an intelligence agency has been passively intercepting someones communications for a year and later acquires the permanent encryption key, it can go back and decrypt all of those communications. This type of interception leaves no trace on the wireless providers network or on an individual users device. In short, GCHQ and NSA have obtained the master keysliterally and figurativelyto unlock millions, if not billions, of the worlds mobile devices. While todays disclosure is bad news for global privacy, there is still some good news. As The Intercept article points out, there are alternatives to relying on Ki encryption. And if youd like to install them, EFF has created easy-to-use guides as part of our Surveillance Self-Defense project: These are just two of the many tools available for secure messaging. Our Secure Messaging Scorecard examines dozens of messaging technologies and rates each of them on a range of security best practices. Of course no method is foolproof. But, as documents published by Der Spiegel in December show, it appears that, as of 2012, the NSA had yet to crack the encryption provided by these technologies. And that, at least, is good news. Please visit the Electronic Frontier Foundation, where this article first appeared, for the latest news in digital privacy and civil liberties. 