Technical feasibility is not something the NSA can wish away. They're not magic. The fact is that keeping a microphone array active all the time would crush battery life, especially if it was constantly recording and transmitting.

Right now, even the FBI can remotely activate the microphone on your phone. Doubt this will change anything in the short run.

I have a Galaxy note phone and if you press the home button twice it activates the Samsung Voice Talk. Sometimes I activate it by mistake and I lock the phone. 2 minutes later a warm fuzzy feeling from my pocket lets me understand that I did this again... They need either less CPU intensive voice recognition or faster cooler CPUs if they want to go undetected with current technology...

Who's to say the NSA wouldn't just add their own hotwords to the "extremely low-power hotword detection"?

They could, but there's also a high chance of discovery. Also, blanket recording hotwords from millions and millions of phones is likely to result in so many false positives as to make the system useless.

For any kind of system to be workable, it's likely they'd have to narrow it down considerably to suspect users. Someone calling the phone number of a person or organization known to be N-degrees separated from real known targets is more likely to yield fruit than scooping up voice conversations from every phone that heard the phrase "bomb making"

Sure, but that's a little different than listening to everything. Not to mention trivial to detect. Just watch CPU consumption and start spouting off trigger words.

>Sure, but that's a little different than listening to everything.

The NSA never cared about listening to everything, that would be completely unmanageable, flagging conversations with key phrases has always been the course of action.

>Not to mention trivial to detect. Just watch CPU consumption and start spouting off trigger words.

It'd also be trivial to detect that you were using a CPU usage monitor and turn off those keywords, viruses do these sorts of things all the time to avoid detection.

That's not correct. Since 2001, the NSA has been retasked to recording all SIGINT information, and figure out what's relevant later. This was the reasoning behind NSA Total Information Awareness (hence the name,) as well as its successor programs including PRISM, FAIRVIEW, MARINA, BASKETBALL, etc.

Also, if you want an undectable CPU monitor, just use a temperature sensor strapped to the processor. Temp-monitoring was even used to find TOR hidden services.

It would still be useful to have it constantly listening while charging.

"Roving bug" capability is not magical. It was revealed in a court case in 2006, in a Nextel feature phone. It is probably implemented in the phone's baseband processor.

Operating a roving bug does use the phone's battery when active, of course. The tricky part is that can be activated when the phone is nominally off, probably by means of the phone waking up periodically and listening for special commands from the network.

If my surmise is correct and this feature is built into the baseband, depending on the system architecture and power management, a roving bug might use only a very small part of a smartphone's relatively large battery.

Roving bugs require secret cooperation from network operators and from chip makers (baseband firmware engineers, specifically). Makes one wonder how well these confidential cooperative agreements have held up as more chip makers are located in the PRC.