It’s hard to overstate the role that Wi-Fi plays in virtually every facet of life. The organization that shepherds the wireless protocol says that more than 48 billion Wi-Fi-enabled devices have shipped since it debuted in the late 1990s. One estimate pegs the number of individual users at 6 billion, roughly 70 percent of the world’s population.
Despite the dependence and the immeasurable amount of sensitive data flowing through Wi-Fi transmissions, the history of the protocol has been littered with security landmines stemming both from the inherited confidentiality weaknesses of its networking predecessor, Ethernet (it was once possible for anyone on a network to read and modify the traffic sent to anyone else), and the ability for anyone nearby to receive the radio signals Wi-Fi relies on.
Ghost in the machine
In the early days, public Wi-Fi networks often resembled the Wild West, where ARP spoofing attacks that allowed renegade users to read other users' traffic were common. The solution was to build cryptographic protections that prevented nearby parties—whether an authorized user on the network or someone near the AP (access point)—from reading or tampering with the traffic of any other user.