Data imaging and hashing
Imaging refers to the exact copying of data either as a file, folder, partition, or entire storage media or drive. When doing a regular copy of files and folders, not all files may be copied due to their attributes being set to the system or even hidden. To prevent files from being left out, we perform a special type of copy where every bit is copied or imaged exactly as it is on the current medium as if taking a picture or snapshot of the data.
Creating a copy of each bit of data exactly is referred to as creating a physical image. Performing a bit-stream copy ensures the integrity of the copy. To further prove this, a hash of the original evidence and the physical image are calculated and compared. A hash can be compared to a digital fingerprint of the data whereby an algorithm such as MD5, SHA1, SHA-256, or even SHA-512 can be run against the evidence data to produce a unique output. If one bit changes in the evidence and the hash is again calculated...