Introduction

Before you can begin analysing evidence from a source, it first of all needs to be imaged. This describes a forensic process in which an exact copy of a drive is made. This is an important step, especially if evidence needs to be taken to court, because forensic investigators must be able to demonstrate that they have not altered the evidence in any way.

The term forensic image can refer to either a physical or a logical image. Physical images are precise replicas of the drives they reference, whereas a logical image is a copy of a certain volume within that drive. In general, logical images show what the machine’s user will have seen and dealt with, whereas physical images give a more comprehensive overview of how the device works at a higher level.

A hash value is generated to verify the authenticity of the acquired image. Hash values are essentially cryptographic digital fingerprints which show whether a particular item is an exact copy of another. Altering even the smallest...