Is there any advantage in encrypting sensor data that is not private?

Question

Some sites, such as this article on end-to-end encryption for IoT, suggest that all traffic sent across the IoT network should be encrypted, saying:

Enterprises, government agencies and other organizations should take adopt [sic] an “encrypt-everything” strategy to protect against IoT-enabled breaches.

I can understand the need to encrypt any data that could be confidential, such as the commands to lock/unlock a 'smart lock' device, but is it really necessary to encrypt everything, such as the sensor that reports the current thermostat reading?

Is it simply the case that "encrypt everything" stops people from forgetting to encrypt data that really ought to be encrypted, or is there a real benefit from using cryptography, despite the extra power, time and cost of it?

Answer 1

Absolutely, because:

1. A secure device and channel means that you can trust the data. Yes, the actual temperature is not very private, but an attacker can provide false temperatures and cause an undesirable response (e.g turning heating on unneccesarily). This is how stuxnet worked, by misreporting the speed of the centrifuges, causing the control system to make them go faster until they broke. Note that a secure channel is not only encrypted, but authenticated and integrity-protected. Integrity is what matters here.
   Encryption alone does not let you trust the data: an attacker can modify encrypted data even if they don't know exactly what they're modifying. Even authentication alone does not let you fully trust the data, as authentic data can be replayed. You need a protocol that guarantees data integrity.
2. It's difficult to tell the difference between a faulty device and a compromised device. Detection and repair of faults is difficult and costly, so not having to repair devices (or debug the entire system) is worth putting in some security.
3. Within a broader ecosystem you don't want some devices with encryption and some not, as this increases costs, maintenance, and management of devices. If you cannot say, for certain, that no private data will be transmitted in a few years' time on the system (not just the device), then it may be safer to engineer it now.
4. Your definition of private data may be wrong, and unless you're checking it with auditors and regulatory experts across the regions in which you operate, assume that the data is private. GPS co-ordinates, and even IP addresses can be considered personally identifiable by some regulatory frameworks.

Answer 2

Sensor reports to a current thermostat reading feel very private to me. A burglar could use the data to find out when a person is at home. After the house got robbed the owner might decide it's a good idea to sue the manufacturer of the thermostat violating their privacy and thus enabling the burglary.

Is this the kind of legal risk a manufacturer of the thermostat wants for their products? Do you want to argue in front of a court that it's completely fine for your company to give burglars the information that they need to know when to break into the homes of your customers?

Answer 3

Yes, there is advantage to encrypting all communications. You wouldn’t post asking of there is any advantage to locking your house, would you?

There question is not of whether, but of how much, advantage there can be.

One of the greatest security experts Bruce Schneier, who has a great blog, btw, will tell you that you can't make things totally secure. What you can do is make them secure enough to make the cost of cracking them more than the benefit from doing so.

In crude financial terms, if it costs $100 to break into somewhere and get $5, the potential intruder is deterred, even though it is possible to break in.

In crude social terms, if I have a visible alarm, security cameras, motion activation floodlights and a pack of hounds, a determined burglar could still break in to my house. But if your house next door looks the same and doesn't have such deterents ...

You can read a lot of his musings on the IoT, by Goggling for Bruce Schneier iot, including

• Security Economics of the Internet of Things
• Regulation of the Internet of Things
• Real-World Security and the Internet of Things
• We Need To Save the Internet From the Internet of Things
• Major IoT disaster could happen at any time

Random Bruce Schneier fact #81

Bruce Schneier taught Chuck Norris how to divide by zero as they stood silent in an elevator.

Answer 4

It's always a choice of the designer/developer. But using encryption and other security measures becoming a necessity in these days.

As per an example, sensor that reports the current thermostat reading, can be taken control by an intruder to send you false signals. (They can have some strategy to rob you by doing so, who knows ?)

You may have heard that you cannot make systems that are Unbreachable. You only make systems which are harder to breach !

No matter what steps you've taken, they still can break them. Hence why bother to take some extra steps to make it safe ?

Answer 5

In addition to other answers, if the data is sent in plaintext it can be modified.

Apart from mentioned problems faking data can cause (turning heat to the max due to lying thermometer in the middle of hot summer might lead to fire hazard, for example) manipulating data can lead to compromise of IoT device, and everything that accesses it (for example, you notebook might be checking temperature, but HTML page showing temperature could be replaced in-transit with computer virus designed to infect your internal network, or JSON data might be modified to break into application reading malformed data etc).

Not that implementing security is without its risks, especially in IoT world. Security is hard, and implementation of it usually vastly increases codebase, and with it number of bugs (and thus possible attack vectors / exploit opportunities). IoTs rarely get firmware upgrades, so when a IoT device without auto-update has a problem, it is almost guaranteed to provide Botnets with extra zombie machines.

And yes, auto-upgrade itself is not without issues - from privacy issues to possibility that evildoers will take control of it if not implemented properly; but it should be lower risk than hoping your first firmware will be without any security bugs allowing attackers to increase their zombie ranks.