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The Internet of Things that go Bump in the Night

February 29, 2016

As a young scientist, I would often emulate the photons of the waveguides I studied by bouncing off the walls of the hallway between the bedroom and kitchen as I rushed to start my day. On one such trip, I accidentally nudged a lever on the setback thermostat for our house, a fact I discovered the next morning when I awoke to an unusually chilly room. Well, accidents happen, this one mildly affecting the four members of my family that day, and the fix took just a second.

Light wave in a graded-index fiber
Light wave in a graded-index fiber. (Created using Inkscape.)

Some newer thermostats are packed with much more technology than my mechanical thermostat. They're Internet-connected, so they can be controlled anywhere using devices such as smartphones. This sounds like a nice feature, but some owners of the Nest smart thermostat found last month that the same problems that plague their computers can affect their thermostat as well.[1]

The Nest thermostats are designed to automatically update their software through the Internet, but an update caused a battery drain in some devices that resulted in erratic behavior, or a complete shutdown resulting in no heat on a cold January day. Unlike the quick fix of my thermostat, some of the Nest units needed a total "reboot." This involved unplugging the devices and manually restarting them. This high-tech tool with added convenience turned out to be quite inconvenient.

Smart thermostats are an example of an emerging technology known as the "Internet of Things (IOT)." The emergence of a new Internet addressing scheme called IPv6 allows 2128 separately-accessible devices to be connected to the Internet. That's about 3.4x1038 addresses, or more than 1028 unique addresses for each person on Earth. By one estimate, there will be 50 billion devices connected to the Internet by 2020.[2] I wrote about the IOT in an earlier article (The Internet of Things, October 11, 2013).

Whether or not people really need an Internet-connected toaster, it's estimated that the IOT could increase the U.S. gross domestic product by 2%-5% by 2025.[3] This economic benefit would arise from improved systems in manufacturing, transportation, health care, and waste management.

As we've learned from our experiences with spam email, computer hacking, targeted advertising, and individual tracking by smartphones and electronic toll systems, Internet technology has a definite dark side. Similar problems will arrive with the IOT. Economist, Gérald Santucci, writes that that the present safeguards on information privacy are largely inadequate, and they threaten personal privacy and the rights of individuals as we progress to this "Internet of Everything."[3-4]

Be afraid, be very afraid
This memorable phrase from the 1986 remake of "The Fly," could be a motto for the Internet of Things. (Created with the GNU Image Manipulation Program, GIMP.)

Software developers continue in their attempts to secure the usual Internet devices against hackers and corporate/government snooping. As this list shows, there are quite a few ways, such as the man-in-the-middle attack, to hack your personal information. Along with these attack modes, IOT devices and devices using RFID technology have additional problems that involve what are called side-channel attacks.

Portion of an RFID chip (MIT)Portion of an RFID chip.

The gold wire loop serves as both an antenna and a means to extract power from the device that reads the chip's information.

(MIT image.)

In a side-channel attack, seemingly irrelevant details of device performance can lead to knowledge of its internal workings. These might be the time it takes to reject the wrong password, or fluctuations in its power usage as it receives external commands. RFID devices are especially vulnerable to such attacks, since they are usually powered by the reader device, and a rogue reader can play tricks with their power source as it attempts to discern the working of their internal software.

As Chiraag Juvekar, a graduate student in the Department of Electrical Engineering and Computer Science at MIT, explains, side-channel extraction of things like passwords is difficult to do.
"The idea in a side-channel attack is that a given execution of the cryptographic algorithm only leaks a slight amount of information... So you need to execute the cryptographic algorithm with the same secret many, many times to get enough leakage to extract a complete secret."[5]

One way to thwart such attacks is to frequently change the secret key used in sending and receiving encrypted messages. A simplified scheme of this type is used in the rolling code software for vehicle keyless entry. However, a reader-powered device is vulnerable to an attack in which the reader repeatedly cuts the power before the chip changes to another secret key. This is an easy way to circumvent software that limits on the number of incorrect password entries before shutting down.[5]

Warded key, 17th century, probably German (Walters Art Museum)
People have been keeping secrets for a long time. This is a warded key from the 17th century, probably German. (Key image from the Walters Art Museum via Wikimedia Commons, modified.)

Juvekar is first author on a paper presented at the 2016 International Solid-State Circuits Conference, San Francisco, that describes a side-channel safe RFID chip developed jointly by MIT and Texas Instruments.[5] The tactic that they used is to make certain that the chip always remembers its last state when power is removed. To do this, the research team integrated non-volatile memory into the hardware.[5] The situation is analogous to an interrupted chess game when the board pieces are left undisturbed so that play can resume again at any time.

The chips incorporate ferroelectric crystal layers for two purposes. The first use is for energy-storage capacitors so some operations can be continued when the external power source is removed. The second use is for a non-volatile memory that contains a record of the chip's last state. When external power is restored, the chip continues where it left off, including operations needed to change the key. It won't respond to external commands until this is done.[5]

The MIT RFID chip is somewhat slower than others, since it needs time to charge its internal energy store before it accepts commands. The device, however, still gives thirty readings per second, which is sufficient for most RFID applications. Says Ahmad Bahai, chief technology officer at Texas Instruments,
"In the age of ubiquitous connectivity, security is one of the paramount challenges we face... Because of this, Texas Instruments sponsored the authentication tag research at MIT that is being presented at ISSCC. We believe this research is an important step toward the goal of a robust, low-cost, low-power authentication protocol for the industrial Internet."[5]

Some funding for this research came also from Denso, a Japanese automotive company.[5]


  1. Jaikumar Vijayan, "Nest Issues Update to Fix Thermostat Glitches," eweek, January 11, 2016.
  2. Dave Evans, "The Internet of Things - How the Next Evolution of the Internet Is Changing Everything," Cisco Internet Business Solutions Group. April, 2011.
  3. Michael Mandel, "Can the Internet of Everything bring back the High-Growth Economy?" Progressive Policy Web Site, September 12, 2013.
  4. Internet of Things Demands New Social Contract To Protect Privacy, Security Ledger Web Site, September 19, 2013.
  5. Larry Hardesty, "Hack-proof RFID chips," MIT Press Release, February 3, 2016.
  6. Larry Hardesty, "Secure computers aren't so secure," MIT Press Release, October 30, 2009.

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