How difficult is it to wiretap someone’s phones or digital communications? Is it possible to tell if your communications are being tapped?

From a technological perspective, wiretapping has always been feasible and rather easy. Most commercial systems are designed with such capabilities. For instance, 4G LTE, the mobile communications system used around the world, is designed with lawful interception as part of the standard. For wired internet access, most internet service providers deploy deep packet inspection technologies that search data for non-compliance, viruses, spam, and the like while also intercepting traffic. Wiretapping without a warrant requires more advanced tools but remains feasible in many cases.

Newer technologies relying on end-to-end encryption—such as the anonymous communication software Tor—aim at higher levels of privacy to protect both the content of communications as well as meta-data. However, they also have limitations and recent research indicates that they are continuously being attacked.

It is possible to detect and protect against some of the typical wiretapping techniques using the right tools, including end-to-end encryption. However, it is very hard to protect against targeted and highly sophisticated techniques that are hard to detect and defeat.

How does wiretapping work? Does it need to be set up in person or can it be done remotely?

Lawful interception of cellular communications does not require a physical presence since it is a functionality of most systems. Wiretapping without a warrant can, for instance, be done by downgrading a cellular communication to a second-generation 2G one, where it is easy to pose as a legitimate base station, then intercepting or injecting voice calls, SMS, and data. This is because, unlike more recent cellular networks, 2G networks only authenticate the mobile to the base station and not the other way around.

Today, it is easy to build a rogue GSM, or global system for mobile communication, base station for a few hundred dollars—an approach that would typically require a physical presence. In recent years, however, with the popularity of mobile apps and the pervasiveness of smart- and connected devices, including software radios, it has become possible to turn many devices into wiretapping devices, therefore alleviating the necessity of physical presence.

Intercepting encrypted https traffic is also feasible through a variety of means, including exploiting vulnerabilities of the design, implementation, and deployment. But you can also do it through simpler approaches, such as obtaining certificates from an established certification authority.

What’s the difference between wiretapping and other types of surveillance, such as hacked communications or a data breach?

Hacking the communications and data breaches typically imply illegal activities. A data breach might reveal secret passwords or keys that facilitate wiretapping. Hacking into communications infrastructure also makes traffic interception feasible on phone and some data traffic.

How have new technologies changed the feasibility and difficulty of wiretapping?

Driven by research, new technologies are emerging to make wiretapping significantly harder than in the past. Today, careful users have some choices in protecting their communications against typical adversaries. However, protecting users’ communications, and especially meta-data, against sophisticated adversaries remains a challenging problem due to the myriad layers of technology that need protection—the hardware, software, protocols design, manufacturing, integration, configurations, operation and management, and so on.