Introduction
Steganography is the art of hiding or concealment of secret information within an ordinary message or file. The purpose is to hide the existence of this information from a third party so as to covertly pass messages along without being detected. (1)
Throughout this report, we will discuss what a digital forensics investigator should know in relation to Steganography in electronic communication. We will talk about the history of steganography and then discuss how steganography techniques works in comparison to cryptography and digital watermarking. We will then talk about two different types of image and audio steganography methods that can be used to conceal hidden information. These methods are Least Significant Bit Insertion (LSB) and Discrete Cosine Transform (DCT). We will then talk about a tool that can be used hide and extract hidden
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The word dates back to the book, “Steganographia”, which was written in the 15th century by a German man named Johannes Trithemius. Trithemius was active in the Renaissance and worked on three books which were about magic. On the surface, these books are perceived to be written about magic but secretly, Trithemius had concealed encrypted Cryptographic and Steganographic information and in a way, Steganographia was actually a case of Steganography. (2,3)
The technique of Steganography first dates to ancient Greece. A man named Histiaeus, who was being held prisoner by King Darius, had shaved the heads of his most trusted slaves and tattooed messages upon their scalp. When their hair grew back, he would send them out on a mission to deliver these messages to the leader of Miletus, Aristagoras. As a result, a revolt began and he was released. This is the earliest known method of Steganography but over the last few centuries it has being used in a variety of ways.
Back-masking is the process where a recording is normally recorded, but the message is embedded in the song in a way that if the record is played backwards there is some kind of message in the song. This means that the song can be played both forward and backwards and the song will have two different meanings. This process was made popular by the Beatles.
National Institute of Standards and Technology. (2012). Computer Forensics Tool Testing Handbook. Retrieved March 23, 2014 from http://www.cftt.nist.gov/CFTT-Booklet-Revised-02012012.pdf
“Advance in Forensics Provide Creative Tools for Solving Crimes.” www.ctcase.org. Np. n.d. Web. 17 March 2014.
Computer forensic investigators have the tough job of finding a “binary” smoking gun. In order to do this, the investigator must be trained, qualified and have an “eye” for things that others may not see. The investigator must take into consideration that each computer examination is unique (Solomon 2011). Understanding the hardware, its operating system and other peripheral or network devices make this job that more difficult.
The first recorded use of steganography dates back to the early Greeks and the ruler, Demaratus. As king of Sparta, Demaratus ruled from 515 to 491 B.C. At this time, it was common to write on waxed tablets. To communicate a warning of an impending attack on Greece by the Persian ruler Xerxes, Demaratus scraped the wax off of a wooden tablet, inscribed a message, and then covered the tablet in wax once again. In this way, the tablets carried secret information to the intended recipient without arousing suspicion. Other times of conflict are rich with examples of steganography. The Underground Railroad used quilt patterns to direct slaves on their journey northward, cryptographic writing was used numerous times in both World War I and II, and
Image splicing forgery technique involves composition or merging of two or more images changing the original image significantly to produce a forged image. In case images with differing background are merged then it becomes very difficult to make the borders and boundaries indiscernible. Figure 2 below shows an example of image splicing where the face of two different people is combined to form a forged image.
- In Ancient Egypt, papyrus was used for writing maybe as early as from First Dynasty, but the first evidence is from the account books of King Neferirkare Kakai of the Fifth Dynasty.
Codes have been around for centuries ranging from wax, invisible ink, Morse code, the Enigma used by the Germans during World War II and now steganographic. Steganography is the latest form to insidiously hide information over the Internet without a trace of a file being altered. You are able to hide messages within images, voice or music. Steganography is an ancient method of hiding messages. Today messages are hidden in images and music. Steganography can be traced back to the ancient Greek who would write messages on tablets and cover them in wax. This made the tablets look blank and unsuspicious (Kolata, F4). Citizens of ancient civilizations would tattoo messages on their shaved heads. They would then let their hair grown in and travel across enemy lines to deliver the message (Seper, G1). During World War II the Allies placed a ban on flower deliveries with dates, crossword puzzles and even report cards (Kolata, F4) for fear of a message being hidden with in. Steganographers first alter their data by using encryption and then place the image into a pre-select image. Steganographers look for a piece of code that would be the least significant and look the least altered to the human eye (Kolata, F4), being as inconspicuousness and random as possible. This makes the messages undetectable unless you knew that there is a message hidden and you were able to crack the code.
The data a computer forensics acquisition tool collects is stored as an image file in one of three formats. Two formats are open source and the third is proprietary. Each vendor has unique features, so several different proprietary formats are available. Depending on the ...
What did they do ? Before we talk about it any further, we have to know some definitions that we use in digital forensics and digital evidence, not only two of them but the others too. This chapter will explain about it . Before we talk about it any further, we have to know the definition of what we are talking about. In the introduction we already know what digital forensic and digital evidence shortly are. In this chapter, we will more explore what they are, and some state that we found when we search about digital forensic and digital evidence. Computer forensics is a broad field and applied to the handling of crimes related to information technology. The goal of computer forensic is to securing and analyzing digital
The biggest challenge investigators face and who is involved with high tech crime is the fast-paced constant evolving nature of technology. When companies come out with new devices or new versions of old devices which is almost all the time, and those who gather digital evidence must remain current to be able to locate and preserve all potential evidence. As technology evolves the capacities of these devices will rapidly increase while their form factor grows continually smaller. Investigators must preserve digital evidence to make sure it is suitable for presentation in court as well. Investigators must first never change a crime scene or alter evidence. It is their goal to document and preserve the scene exactly as it was when the crime occurred. Extreme caution and care is needed because the mere act of documenting or cataloging a crime scene means that investigators are interacting with the scene. The second concern is the physical fragility of the evidence. Care must be taken to keep items from getting wet, stepped on etc, this can also be applied to digital evidence. Investigators have been able to examine hard disk drives that have been through fires because the drives are usually air and water tight and impervious to temperatures into the thousands of degrees. The third issue is that digital evidence can be lo...
Computer science is a vast field that includes nearly everything relating to computers. Everyday there is information transmitted all over the Internet. Pictures are uploaded, transactions are made on thousands of online retail websites, and banking transactions take place everyday on the Internet. All of these transactions have created a need for secure communications. People wish to keep things like banking, medical, and political information from the eyes of unwelcome parties. This has created a need for cryptography. Cryptography is the science or study of the techniques of secret writing, especially code and cipher systems, and is used by everyone from the average citizen to the government and military.
Jost, Kenneth. "Examining Forensics." CQ Researcher Online. N.p., 17 July 2009. Web. 29 Apr. 2014. . How criminals can use photoshop to eliminate evidence
Digital evidence Digital data stored in computers or digital systems or transmitted by them can be Use in proving or denying a crime may be digital or non-digital. The main aim of digital criminal analysis is to address digital crimes, which are committed using computer hardware or those located on digital systems or networks. Digital criminal analysis is the use of technology techniques in the criminal investigation of illegal cases, including the examination of the device or the target system, analysis of operations and retrieval of data and files in order to obtain a digital evidence used in legal
Cryptography is the study or science of techniques of secret writing and message hiding. Cryptography constitutes any method in which someone attempts to hide a message, or the meaning in some medium. One specific element of cryptography is encryption, which hides the data or information by transforming it into an undecipherable code. Encryption uses a specified key to perform the data transformation. The length of the key for the encryption