In theory, it is possible to intercept unencrypted data transmitted by handheld devices through wireless signals to achieve data theft. The following is described in detail from both the technical principle and the actual feasibility： ### Technical principle -**Wireless communication basics**: Handheld devices (such as mobile phones and tablet computers) communicate with base stations or other devices through wireless signals. Common wireless communication technologies include Wi-Fi, Bluetooth, cellular networks (2G/3G/4G/5G), etc. These wireless signals propagate in the air. In theory, as long as the signal is within the coverage range, it is possible for people with corresponding receiving equipment to obtain the data transmitted therein. -**Signal monitoring principle**: An attacker can use some specialized equipment and software to monitor wireless signals. For example, a spectrum analyzer can be used to scan wireless signals in a specific frequency band to obtain information such as the strength, frequency, and modulation method of the signal. For unencrypted wireless communications, such as open Wi-Fi networks or unencrypted Bluetooth connections, an attacker can directly parse the data content transmitted therein. -**Wi-Fi**: The 802.11 protocol family defines the communication standard of Wi-Fi. In the case of unencrypted (such as no password is set or the insecure encryption method WEP is used), an attacker can capture wireless data packets, which may contain various data sent and received by the device, such as the content of Web pages browsed on the Internet, and the password of the logged-in account (if it is not carried out during transmission).Encryption processing) and so on. -**Bluetooth**: Bluetooth technology is used for short-range wireless communication. Similarly, in an unencrypted Bluetooth connection, an attacker can monitor data transmitted between devices, such as audio data transmitted between a mobile phone and a Bluetooth headset, and health data transmitted between a mobile phone and a smart bracelet. ### Practical feasibility -**Environmental restrictions** -**Distance and range**: The strength of the wireless signal will rapidly decay as the distance increases. Generally speaking, to effectively intercept data, an attacker needs to monitor at a closer distance to the handheld device. For example, for ordinary Wi-Fi networks, in the case of unobstructed, the effective coverage may be within tens of meters; the effective distance of Bluetooth is usually about 10 meters. This limits the area where an attacker can eavesdrop. -**Signal interference**: In a complex electromagnetic environment, wireless signals are vulnerable to interference from other signals. For example, in a place where there are multiple wireless devices working at the same time around, various signals are intertwined with each other, which will affect the attacker's monitoring effect of the target signal. In addition, obstacles such as buildings and walls will also block and scatter wireless signals, further weakening the signal strength and increasing the difficulty of monitoring. -**Legal and ethical constraints** -In most countries and regions, it is illegal to intercept other people's wireless communication data without authorization. This kind of behavior infringes the privacy rights and freedom of communication of others and will be sanctioned by law. Therefore, from the legal point of view, there is a great risk of this kind of data theft, and the perpetrator will face legal responsibility. -**Technical threshold and cost** -To achieve effective interception and data analysis of wireless signals, an attacker needs to have certain professional knowledge and technical capabilities, as well as corresponding equipment. Professional wireless monitoring equipment is expensive, and the operation and use of these equipment requires relevant technical skills, which are not easy for ordinary personnel to do. This also limits the widespread occurrence of this kind of data theft to a certain extent.