In mobile device forensics, what distinguishes a physical acquisition from a logical acquisition, and when is a physical acquisition necessary?

In mobile device forensics, a physical acquisition involves creating a bit-by-bit copy of the entire contents of the device's storage, including allocated and unallocated space. This means acquiring all data, including deleted files, fragments, and system data. A logical acquisition, on the other hand, involves extracting data from the device using its operating system's application programming interfaces (APIs). This method only retrieves data that is accessible to the user or applications, such as contacts, call logs, SMS messages, photos, and application data. A physical acquisition is necessary when a more thorough examination of the device is required, such as when recovering deleted data, analyzing file system structures, or bypassing security features like encryption. It is also necessary when logical acquisition is not possible due to device damage, operating system restrictions, or lack of support from forensic tools. Physical acquisition techniques, such as JTAG or chip-off, provide access to the raw data on the device's storage chips, allowing for a more complete and in-depth analysis. Logical acquisitions are typically faster and less invasive, but they may not provide access to all of the data on the device. The choice between a physical and logical acquisition depends on the specific goals of the investigation and the capabilities of the forensic tools and techniques available.