Using spellcheck? Electromagnetic fields could reveal your writing

Georgia Tech is studying better software and hardware designs to prevent electronic snooping

Georgia Tech researchers Alenka Zajic and Milos Prvulovic use an AM/FM radio to pick up side-channel signals from a cell phone, which could be used to learn what computations are being done by the device.

Georgia Tech researchers Alenka Zajic and Milos Prvulovic use an AM/FM radio to pick up side-channel signals from a cell phone, which could be used to learn what computations are being done by the device.

It has long been known that subtle electronic fields and noises emitted by computers can reveal clues about your activity, a powerful spying method that can be done from a few feet away.

These so-called "side-channel signals" can be collected by antennas or microphones and through analysis could reveal sensitive data such as encryption keys.

It's not known if spy agencies are already using these methods, but the many academic studies outlining potential attacks would suggest it's probably a growing part of signals intelligence.

Researchers from the Georgia Institute of Technology have embarked on a three-year project to figure out how these electronic signal leaks could be prevented by redesigning hardware and software.

Milos Prvulovic, an associate professor with Georgia Tech's School of Computer Science, said his team has been looking for potential vulnerabilities in applications or hardware designs that might make such signals collection easier.

"I don't want to demonstrate an attack in order to be able to defend against it," Prvulovic said in a phone interview Thursday. "Then, the defenders are always playing catch up with the attackers."

Much effort has gone into trying to stop side-channel attacks from being successful against specific pieces of code, such as a cryptographic kernel.

But much less work has been done in leakage at a broader architectural level, such as what features are the strongest leakers, they write in their research paper.

To look into this, the researchers developed a new metric called "Signal Available to Attacker" (SAVAT), which measures the side-channel signal generated by a single instruction difference when a program is executing.

SAVAT quantifies the side channel signal's dependence on instruction-level differences. The metric allows programmers to modify their code to prevent such high differences from being detected, especially when processes are underway that deal with sensitive information.

They looked at the electronic emanations from three Windows XP laptops running 11 different instructions, as well as some mobile devices.

As expected, some signals were stronger than others depending on what components were involved. Two instructions executed on-chip tend to be quieter than a signal generated by an on-chip instruction that uses off-chip memory, according to their research paper.

Collecting those signal differences can reveal what an application is doing and could be used, for example, to obtain cryptographic keys without trying to break the encrypted content in other ways, Prvulovic said.

Over the years, people have become very good at collecting signals and matching that to a person's activity. During their work, Prvulovic and his colleagues discovered an interesting peculiarity about spellcheckers, which isn't mentioned in their paper.

There's not a lot of signal that comes from a computer running a word processing program that has spellcheck turned off, Prvulovic said. It's relatively difficult for an attacker to tell what key is pressed.

But turn spellcheck on, and things get really noisy. The signals can be picked up by an AM radio, Prvulovic said. In fact, the processing is so loud, it's audible: a person can hear it.

Each keystroke causes the spellchecker to look up the word in a dictionary to try to catch a mistake and flag it.

"It turns out that spellchecking is orders of magnitude more activity than you would normally get for just a simple key press," he said. "Modern software does a lot of stuff that is convenient but horribly computationally intensive. That creates differences that can be picked up."

Send news tips and comments to jeremy_kirk@idg.com. Follow me on Twitter: @jeremy_kirk

Join the newsletter!

Error: Please check your email address.
Rocket to Success - Your 10 Tips for Smarter ERP System Selection

Tags securityGeorgia Institute of Technology

Keep up with the latest tech news, reviews and previews by subscribing to the Good Gear Guide newsletter.

Jeremy Kirk

IDG News Service
Show Comments

Cool Tech

Breitling Superocean Heritage Chronographe 44

Learn more >

SanDisk MicroSDXC™ for Nintendo® Switch™

Learn more >

Toys for Boys

Family Friendly

Panasonic 4K UHD Blu-Ray Player and Full HD Recorder with Netflix - UBT1GL-K

Learn more >

Stocking Stuffer

Razer DeathAdder Expert Ergonomic Gaming Mouse

Learn more >

Christmas Gift Guide

Click for more ›

Most Popular Reviews

Latest Articles

Resources

PCW Evaluation Team

Edwina Hargreaves

WD My Cloud Home

I would recommend this device for families and small businesses who want one safe place to store all their important digital content and a way to easily share it with friends, family, business partners, or customers.

Walid Mikhael

Brother QL-820NWB Professional Label Printer

It’s easy to set up, it’s compact and quiet when printing and to top if off, the print quality is excellent. This is hands down the best printer I’ve used for printing labels.

Ben Ramsden

Sharp PN-40TC1 Huddle Board

Brainstorming, innovation, problem solving, and negotiation have all become much more productive and valuable if people can easily collaborate in real time with minimal friction.

Sarah Ieroianni

Brother QL-820NWB Professional Label Printer

The print quality also does not disappoint, it’s clear, bold, doesn’t smudge and the text is perfectly sized.

Ratchada Dunn

Sharp PN-40TC1 Huddle Board

The Huddle Board’s built in program; Sharp Touch Viewing software allows us to easily manipulate and edit our documents (jpegs and PDFs) all at the same time on the dashboard.

George Khoury

Sharp PN-40TC1 Huddle Board

The biggest perks for me would be that it comes with easy to use and comprehensive programs that make the collaboration process a whole lot more intuitive and organic

Featured Content

Latest Jobs

Don’t have an account? Sign up here

Don't have an account? Sign up now

Forgot password?