Summary
Highlights
Bill Swearingen, a hacker from Kansas City and co-founder of the Cowtown Computer Congress, is introduced at DefCon 27. This is his 15th year, but first time speaking, as he believes it's time to 'give back' to the community. He touches upon his personal philosophy shaped by his engineer father, emphasizing curiosity and understanding how things work. He states his talk is 'illegal' in all 50 states, humorously dealing with audience hecklers and police presence, reiterating that the talk is about technology exploration, not law-breaking.
Swearingen recounts his past experience with 'iHacked' 10 years prior, where he released a device that triggered emergency preemptive traffic lights to turn green. He shares lessons learned from that experience, including not talking publicly about committing felonies, as selling or using such devices is a federal offense with penalties up to two years in prison and a $10,000 fine.
Driven by a speeding ticket, Swearingen delved into how radar works. He explains that radar measures speed by detecting the Doppler shift of sound waves, primarily using high-frequency radio waves (microwaves). He details the types of radar bands (X, K, Ka) used by police, with K-band being the most common, and highlights that only a tiny fraction of the transmitted signal is reflected back.
Swearingen conducts a live demo with an audience volunteer, a 'Mr. Police Officer', using a modified Hot Wheels radar gun. He demonstrates how to return the same frequency to indicate standing still and then how to slightly adjust the frequency to falsely indicate a moving speed, like 111 mph, by precisely calculating the required frequency shift.
He explains how a device could be built to transmit specific frequencies (e.g., 10.5 GHz for X-band or 24.12 GHz for K-band) to consistently report a desired speed, like 65 mph. He also humorously confirms his father's story about microwaves jamming radar, noting that a microwave oven would report negative speeds to an X-band radar. However, he acknowledges the problem of constant speed in varying speed zones and the legality of radar jamming (illegal since 1996).
Swearingen pivots to laser speed guns (LIDAR), noting that they are regulated by the FDA, not the FCC, and are classified as Class 1 lasers (like laser pointers). Unlike radar, laser measures distance, not speed, by sending a series of pulses and calculating the distance based on the return time. Speed is then derived from multiple distance measurements over time (100-200 measurements per second). He notes that laser jammers are legal in about two-thirds of US states.
He explains that a laser gun only determines speed after multiple pulses. This creates a window for countermeasures. By transmitting a quick pulse immediately upon detecting a laser hit, before the gun receives its own reflection, one can report a false distance (e.g., 100 feet away), causing the gun to return an error. He details how commercial laser jammers use various pulse strategies, including varying returns, and how a gun can be identified by its pulse characteristics to implement specific countermeasures.
Swearingen introduces NOTCHACOTCHA, an open-source laser jammer based on the ESP8266 and designed for automotive installation. It uses a 940nm brute-force mode, pulsing every 1 millisecond, which effectively jams 80% of current laser guns. He mentions it doesn't work against advanced systems like Dragon Eye but hopes the open-source community will help develop more sophisticated countermeasures. The device costs only about $8 to build, and the code is available, encouraging community contributions to create a commercial-grade open-source laser jammer.