Digital Forensics Techniques

This assignment delves into the realm of digital forensics, exploring two key techniques: data acquisition from Linux computers and steganography. It outlines methods for creating disk images using hardware or software tools like ProDiscover Basic and live CDs. Additionally, it discusses various steganographic approaches, including bit-plane complexity segmentation (BPCS) and least significant bits (LSB), for embedding secret messages within graphic files. The assignment provides algorithms for both data hiding and retrieval processes.

Running head: DIGITAL FORENSICS
Digital Forensics
Name of the Student:
Name of the University:
Author Note:

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Task 2
The following method will show how to acquire disk image from a Linux Computer
by using certain hardware or software or both from a crime scene. Linux is an operating
system that is equipped with a number of predefined features of the forensic tools, which help
in forensic data acquisition (Nelson, Phillips& Steuart, 2014). Linux can access the drive,
which is not mounted. The following tools can be used to carry out the acquisition of the disk
image:
 A USB external hard drive with cable
 A forensic Live CD
 Console commands to modify the BIOS of the device to run the Live CD
 Using Shell Commands for Acquisition of data
ProDiscover Basic – Simple digital forensic investigation software permits to make image,
perform analysis and generate report based on proofs found on a drive. The data on a forensic
image can be viewed by looking at the clusters that hold the information or by content
(Sindhu & Meshram, 2012). The Search node present in the tool can be used to search for
specific data from the data sets that are present in the image of the drive. It is required to
create or load a project after the software is launched and evidences are needed to be added
from the Add button. The Content View or Cluster View nodes can then be used to analyse
the data and the Tools menu to perform certain operations against the information. The
Report node performs the function of showing important information about the project to the
user (Rafique & Khan, 2013).

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An external USB, SATA hard drive can then be connected to the suspect computer
with a cable and the images and the reports can be transferred from the computer to the hard
drive for using for forensic examination (Quick & Choo, 2016).

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Task 3
The research requires procedures to embed four secret messages in some graphic files
that have been provided by the lead investigator of a case where the graphic files were sent
from an unknown source to a suspect. The process of hiding any kind of data into any digital
content without causing any kind of degradation to the original digital can be done with a
process known as Steganography. The process includes hiding a data such as a message by
hiding it into different carriers. The purpose of this method is to ensure that particular
information is obtained by a target recipient and not intercepted in the middle of transmission
(Hussain & Hussain, 2013).
Many kinds of modern steganographic techniques are there for this purpose such as
permutation steganography, batch steganography, bit-plane complexity segmentation
(BPCS), chaos based spread spectrum image steganography (CSSIS) and least significant bits
(LSB). There are various processes of hiding secret data in graphic files. It varies among the
approach of various researchers dealing in the concept of Steganography (Al-Shatnawi,
2012).
Some adopt the procedure of embedding data into the audio-visual files. In that
approach the Steganography algorithm contains a cover message, in which the secret content
is hidden. In other researchers’ perspective an algorithm is adopted in which large amount of
data is hidden with high security. The algorithm includes the process of embedding a large
amount of data such as image, audio or text file inside a colour bitmap or bmp image. The
image mentioned above will be filtered and separated where bits replacement takes place on
the accurate pixels. The pixels are selected in a random manner. Another method that can be
adopted in this process is by hiding the data at the corners and edges of the images (Hamid et
al., 2012).

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The procedure of storing large amount of data inside a bmp image file is considered in
this case. The figure given below shows the algorithm for embedding the data inside the
image.
Begin
Input: Cover_Image, Secret_Message, Secret_Key;
Transfer Secret_Message into Text_File;
Zip Text_File;
Convert Zip_Text_File to Binary_Codes;
Convert Secret_Key into Binary_Codes;
Set BitsPerUnit to Zero;
Encode Message to Binary_Codes;
Add by 2 unit for bitsPerUnit;
Output: Stego_Image;
End
Figure 1: Algorithm for hiding data inside the graphic file
(Source: Hamid et al., 2012 )
The figure given below provides the algorithm for the process of retrieving hidden
data stored in the graphic file.

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Begin
Input: Stego_Image, Secret_Key;
Compare Secret_Key;
Calculate BitsPerUnit;
Decode All_Binary_Codes;
Shift by 2 unit for bitsPerUnit;
Convert Binary_Codes to Text_File;
Unzip Text_File;
Output Secret_Message;
End
Figure 2: Algorithm for extracting data from the Graphic file
(Source: Hamid et al., 2012)

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References
Al-Shatnawi, A. M. (2012). A new method in image steganography with improved image
quality. Applied Mathematical Sciences, 6(79), 3907-3915.
Hamid, N., Yahya, A., Ahmad, R. B., & Al-Qershi, O. M. (2012). Image steganography
techniques: an overview. International Journal of Computer Science and Security
(IJCSS), 6(3), 168-187.
Hussain, M., & Hussain, M. (2013). A survey of image steganography techniques.
Nelson, B., Phillips, A., & Steuart, C. (2014). Guide to computer forensics and investigations.
Cengage Learning.
Quick, D., & Choo, K. K. R. (2016). Big forensic data reduction: digital forensic images and
electronic evidence. Cluster Computing, 19(2), 723-740.
Rafique, M., & Khan, M. N. A. (2013). Exploring static and live digital forensics: Methods,
practices and tools. International Journal of Scientific & Engineering Research, 4(10),
1048-1056.
Sindhu, K. K., & Meshram, B. B. (2012). Digital forensics and cyber crime datamining.
Journal of Information Security, 3(3), 196.