Understanding WiFi Security: A Deep Dive into WiFi Issues

A rumor about the dangers of WiFi

　　WiFi has now penetrated our lives, and its radiation has been questioned repeatedly. There have been news reports stating that a pregnant woman’s family went door-to-door asking to turn off WiFi to avoid affecting the fetus, which caused panic among many pregnant women. Another widely circulated piece of information is that “plants near wireless routers do not sprout.”

　　In fact, under normal circumstances, the impact of WiFi radiation on human health and safety can be largely ignored. Currently, there is no scientific experiment or factual data that proves electromagnetic waves can adversely affect biological entities. The effects that can be produced on biological tissues are mainly due to heating effects, but this requires a strong and focused electromagnetic field.

　　In addition to concerns about human health, whether WiFi poses information security issues is also a hot topic of concern. Today, we will hear from industry experts about various aspects of WiFi.

　　Written by Zheng Jiaqiang (Professor at Nanjing Forestry University, School of Mechanical and Electronic Engineering)

　　“Boss, what’s the password?” The boss or waiter knowingly recites a string of numbers, or a phone number or some meaningful combination of numbers, and then the low-head generation… This is a scene you can often see or hear in tea houses, restaurants, coffee shops, car dealerships, and shops in recent years, or perhaps you often do this yourself.

1. What is WiFi?

　　With the rapid development of mobile internet, wireless routers have entered thousands of households (currently a dual-band router costs around 200 yuan), and humanity’s reliance on and demand for WiFi is increasing day by day. WiFi (Wireless Fidelity) was originally an abbreviation for wireless fidelity, and in wireless local area networks (WLAN), it refers to “wireless compatibility certification”, which is essentially a commercial certification and also a wireless networking technology, also known as the 802.11b standard, which is an industrial standard defined by IEEE for wireless network communication. Due to its high speed, reliability, and relatively low networking costs, WiFi technology has an absolute advantage in meeting users’ high-speed data transmission needs within specific areas.

　　Wireless access points (AP, Access Point), also known as wireless bridges or gateways, continuously receive and transmit data in a wireless local area network. Any PC equipped with a wireless network card can share wired local area network or even wide area network resources through an AP. Theoretically, when a wireless AP is added to the network, it can exponentially expand the network coverage diameter and allow more network devices to be accommodated. Each wireless AP typically has an Ethernet interface for connecting wireless and wired networks.

2. Who Pays for Public WiFi Coverage?

　　With the rapid popularization of smartphones and the rise of mobile e-commerce leveraging the integration of online and offline, the public’s call for free WiFi coverage in public areas is growing louder. However, there is no such thing as a free lunch; who builds the WiFi? Who pays? How is it built? Therefore, the sustainable development of WiFi construction commercial operation models is particularly important. According to multiple networks, domestic WiFi operation models mainly include box models, carriage models, port models, and business district models, and I will add one more public welfare model here.

　　(1) Box Model. This is a model where WiFi operators utilize existing broadband from small and medium-sized businesses (mainly catering and entertainment) to integrate and operate scattered urban WiFi resources by providing advertising routers (or set-top boxes) with promotional portal pages for free or for a fee, replacing the original routers of the businesses, such as the Alipay free WiFi plan. In the box model, WiFi operators mainly earn revenue from advertisements and payments, while businesses can gain information pushes, ordering, payment, and other various O2O applications from the advertising routers (or set-top boxes) provided by WiFi operators, but they need to pay for broadband fees themselves. The advantages of the box model are low construction costs, while the disadvantages are scattered businesses, slow scalability, low entry barriers, and high industry competition. Once covered by large commercial WiFi, they will lose their survival space.

　　(2) Carriage Model. This is a model where WiFi operators convert the signals from basic telecom operators’ base stations into WiFi signals (LTE-Fi) within vehicles, achieving “mobile coverage” for buses, subways, high-speed trains, and other means of transportation. For example, 16WiFi, its advantages are low investment, wide coverage, and high user usage rates, which can leverage this advantage to obtain stable advertising revenues. However, the carriage model currently has technical issues, such as the stability of the converted WiFi signals, network speed, and disconnection problems.

　　(3) Port Model. This is a model where WiFi operators implement WiFi coverage and commercialization in public places such as airports and train stations. For example, Airport Free Wi-Fi adopts dedicated lines and professional APs to cover ticket halls, waiting halls, and squares. The advantage of the port model is that it can form a national WiFi network with cities as nodes, but the disadvantage is that its coverage population comes from all over the country, mostly transient visitors in cities, making it difficult to achieve localized applications and local business support. Therefore, this model mainly operates WiFi comprehensive portal applications (news, mobile games, videos, etc.).

　　(4) Business District Model. This is a model where WiFi operators cooperate with urban information infrastructure builders (basic telecom operators) based on a certain commercial model to achieve city-level WiFi coverage and commercialization for large commercial entities in business districts through fiber optic dedicated line access and business district-level AP hotspot construction, providing integrated online and offline operation platform services for shopping centers, department stores, supermarkets, brand stores, catering, leisure, and entertainment businesses in major business districts. Through the mobile smart business district APP mobile client (remote) and WiFi (near-field) client, it provides information interaction and online-offline integrated transaction matching based on location services (LBS) for users and businesses. For example, adding a functional plugin to the WeChat public platform, namely “WeChat Connect WiFi”, can provide a complete and convenient WiFi connection solution for merchants’ offline venues. Through the WeChat ecosystem and open platform system, merchants can better reach offline users and can close the loop between online and offline through WiFi near-field service capabilities, improving merchants’ operational efficiency.

　　(5) Public Welfare Model. This is a public welfare model that adopts operator construction, with government subsidies for maintenance and traffic fees. Operators focus on statistical sampling, big data mining, and innovative business models to offset construction investment and operational costs, exploring profit models in the WiFi 2.0 commercial era. The public welfare model is mainly based on market failures and the convenience of benefiting the public. In already covered public areas, it guides other builders not to build WiFi coverage; to ensure the effectiveness of WiFi usage in covered areas, it optimizes networks according to standards; and in areas with previous overlapping constructions that cause co-frequency interference, it implements dual-frequency signal methods to increase signal strength and solve interference problems. This type of WiFi network can be opened for free, serving as an important information platform for cities to serve citizens, gradually integrating relevant public information resources from various departments and achieving the effect of benefiting the public.

3. Is WiFi Safe?

　　(1) Demonizing WiFi Radiation Phenomenon.According to Yangtze Evening News, there was once a news report that attracted a lot of attention: a pregnant woman’s family went door-to-door asking to turn off WiFi to avoid affecting the fetus, which caused panic among many pregnant women. Another widely circulated piece of information is that “plants near wireless routers do not sprout.” In reality, the most common wireless routers operate at power levels between dozens to hundreds of milliwatts, which is less than the power of an ordinary mobile phone (the maximum radiation power of a phone is 2 watts). Because the intensity of radiation decreases with the square of the distance, compared to mobile phones, wireless routers and other WiFi devices are much farther away from users, which significantly reduces the power density of radiation that people receive. The electromagnetic wave bands used for WiFi are generally from 2.4GHz to 5GHz, which are quite close to the radio frequency electromagnetic wave bands used by mobile phones. The UK Health Protection Agency estimated that even if a wireless router is left on for a long time at a distance from the body, the radiation generated in a year is roughly equivalent to the radiation from a few minutes of mobile phone use. The impact of WiFi radiation on human health and safety can basically be ignored. Currently, there is no scientific experiment or factual data that can prove that electromagnetic waves adversely affect biological entities. The effects that can be produced on biological tissues are mainly due to heating effects, but this requires a strong and focused electromagnetic field. The electromagnetic waves used by WiFi are non-ionizing radiation, and under full load, the tested electromagnetic radiation is 24-31 microwatts per square centimeter, far below the current limit of 40 microwatts per square centimeter set by China’s “Electromagnetic Radiation Protection Regulations” (the EU standard is 450 microwatts per square centimeter, and the US is 600 microwatts per square centimeter). This is comparable to the radiation value of a mobile phone in standby mode, far below the radiation of a mobile phone during calls.

　　（2）WiFi Has Security Risks.WiFi devices have a high level of security; the issue is how WiFi is used. Wireless networks with passwords are generally more secure than free WiFi, and wireless networks provided by operators require users to log in, making them even more secure. However, it is undeniable that there are still considerable security risks associated with WiFi usage. Due to the low technical threshold for commercial WiFi, anyone can set up a WiFi network by purchasing equipment, software, and network services. It is technically very easy to create a false WiFi environment in public places that emits signals to lure users into connecting. Hackers manage to obtain user accounts and passwords because they set up human traps. The hackers do not breach the security of WiFi devices but exploit software vulnerabilities in insecure web browsers. Password-free wireless networks are easier for hackers to compromise. According to reports, Tencent Security announced that it has partnered with domestic commercial WiFi service providers and some businesses to establish the “Tencent Security WiFi Alliance” to achieve WiFi network coverage. Based on Tencent Security’s open platform, the Security WiFi Alliance connects resources from telecom operators, commercial WiFi operators, and businesses to provide free and secure WiFi services; Tencent Mobile Manager establishes a unified security WiFi service standard, allowing users to connect to a secure WiFi network simply by using Tencent Mobile Manager. When using Tencent’s “National WiFi”, as long as you plug it in and scan, it can automatically install drivers to create a WiFi connection, with features such as preventing unauthorized access, blocking malicious websites, and intercepting Trojan fraud.

4. The Future of WiFi

　　(1) Drone-Based WiFi Signal Transmitters

　　It is said that Facebook founder Mark Zuckerberg and Google are constantly competing for drone network services. A few years ago, he quietly acquired the British solar-powered drone manufacturer Ascenta and hopes to develop a drone system that uses low-flying drones to maximize network signal strength, essentially turning drones into flying WiFi signal transmitters. These solar-powered drones can fly continuously in the air for months or even years, aiming to bring internet access to remote areas worldwide. It is reported that a team of surveillance drones serving in Iraq was reassigned to provide WiFi in remote, poorly communicated battlefields. The RQ-7 Shadow drone plays roles such as surveillance and intelligence gathering in the Iraq military, but it has now transformed into the world’s most advanced wireless router, using drones as a hub to compensate for radio signal limitations and increase data transmission channels. This project, organized by the US DARPA, has modified drones that can transmit 1GB of data per second (equivalent to the transmission capacity of a 4G network), allowing access to tactical centers and reference mission data in remote war zones through the internet. This information consists of internal documents that are not carried on person, which can now be viewed on computers. The challenge of this project lies in how to equip existing drones with wireless systems, as the Shadow is not the largest drone, making it difficult to add more equipment. However, DARPA claims to have developed a micro-antenna that can emit high-frequency directional millimeter waves, which can significantly enhance signals through special amplifiers, allowing drones to provide signals at high altitudes without being seen by the enemy. They use external devices to provide wireless services, with the device being only 8 inches wide and weighing just 20 pounds, capable of providing 9 hours of service. DARPA also claims to have developed a point-to-point connection method that can ignore the influence of terrain and obstacles while ensuring signal strength. Currently, the project is still in design topology, but it is unclear what improvements can be made to allow the lightweight Shadow to withstand adverse weather conditions. The plan will incorporate wireless devices into aircraft and ground vehicles and complete docking of four WiFi drones and two ground vehicles.

　　(2) Passive WiFi Technology

　　According to PC World on August 5, 2014, a team from the University of Washington has developed WiFi devices that do not require power, utilizing backscatter technology to combine wireless power and WiFi, allowing them to use surrounding radio wave signals as energy sources and establish connections for data transmission with WiFi networks. Passive WiFi devices may be widely used in the Internet of Things field, connecting a large number of devices to the internet. Traditional WiFi devices consume a lot of power, while backscatter technology will greatly reduce or even eliminate the need for power.

　　(3) LiFi Technology Combining Light and WiFi

　　Light, like radio waves, belongs to electromagnetic waves, and its frequency is 100,000 times that of WiFi hotspot frequencies. The combination of light and WiFi has created LiFi (Light Fidelity, visible light wireless communication, also known as optical fidelity technology), whose technical principle is to use rapid light pulses to wirelessly transmit information (by adding a microchip to an LED bulb, the bulb can become a wireless network transmitter). Information can be encoded in light at different rates, for instance, turning the LED on represents 1, and turning it off represents 0. By rapidly switching on and off, information can be transmitted (different colors of LEDs can also be used to transmit data), meaning that signals can be transmitted through rapidly flickering bulbs at speeds fast enough to reach billions of times per second. Due to the LED’s intensity, the human eye hardly perceives the rapid changes in light, while light-sensitive sensors can detect these changes, and various mobile receiving ends can decode the data through visible light. Fudan University has already adopted light to replace radio waves for data transmission, achieving speeds 10 times faster than WiFi, demonstrating that four computers can connect through a single bulb, with offline maximum speeds reaching 3.25G and average online speeds of 150M, making it the fastest “light internet” in the world. The spectrum of light is 10,000 times larger than that of radio frequencies, meaning LiFi has greater bandwidth and higher speeds, and network setups require almost no new infrastructure; “where there is light, there is network signal; turn off the light, and the network is gone.” However, LiFi still has limitations, such as not being able to penetrate walls. Although it is more secure, if the light is blocked, the network signal will be cut off; in practical applications of LiFi technology, can you tolerate being under constant light exposure? Due to various limitations, LiFi can only serve as a supplementary method for wireless transmission in small spaces, such as providing WiFi through LiFi technology for underwater operations.

　　(4) High-Altitude WiFi

　　Passengers on airplanes have long needed to turn off mobile devices, relying on televisions and magazines to pass the time. However, WiFi connections on airplanes are becoming increasingly common. “Sky WiFi” can be categorized into “local area networks” and “earth-to-sky connections”. Typically, airlines take three steps: first, equip each airplane seat with a tablet; second, establish an in-cabin local area network to achieve interconnectivity within the cabin; third, establish communication between the sky and the ground. Technically, there are two main ways for earth-to-sky connections: one is through internal wireless networks installed on the aircraft and satellites for communication, then through satellites to ground stations for communication, and the ground stations connect to domestic network operators for global coverage, but the biggest issue is slow speed, only achieving “narrowband” transmission; the other method is to use onboard equipment to establish network links with ground base stations, equipping airplanes with dual modems and directional antennas. When the airplane is flying overhead, it exchanges data with these networks, but the problem is that base stations must be modified, and service is limited to the segment of the flight where the base stations have been modified. Additionally, when the airplane is over the ocean or too far from ground base stations, speed and reliability can be affected.

　　(5) Global WiFi Coverage

　　Covering every corner of the world with wireless networks sounds like a beautiful vision. However, an ambitious media development investment fund company in the US intends to make it a reality, with a project called “Outernet”. This company is in contact with NASA, hoping to receive assistance in conducting signal release tests at the International Space Station. In the later stages, they will also need NASA’s help to send hundreds of mini-satellites (cubesats) into designated orbits. According to the plan, once the satellites reach their predetermined orbits, they will receive network data released from ground base stations, and the satellites will need to decode this data and convert it into wireless network signals continuously released to the Earth, providing WiFi services worldwide. The company expects to launch hundreds of mini-satellites into low Earth orbit by June 2015, allowing any electronic terminal in any corner of the world to connect and enjoy wireless networks. The future remains uncertain.

　　(This article is reprinted from Zheng Jiaqiang’s blog on ScienceNet)