Various techniques are employed to detect the presence of steganography. Shorter signatures are more likely to be present in non-stegoed images by random chance, thereby producing false positives in signature-based detection software. A detected signature almost always indicates the presence of steganography ("StegAlyzerSS," 2006). Signatures are also detectable by steganalytic software. Signatures are means of associating the image with a specific steganographic application in order to identify which steganographic application must be employed for image extraction. Some applications leave signatures, in the images in which they have hidden information. Artifacts consist of changes to associated information and are not necessarily detectable by analyzing only the pixilated composition of the image (Wayner, 2002).Įmbedding applications employ these steganographic algorithms in various ways and to varying degrees of effectiveness and stealth (Wayner, 2002). Image artifacts are observable anomalies in various characteristics of the image which indicate action of steganographic embedding software. The term 'file artifact' is used to refer to the evidence left by the steganography-producing software application on the host system that generated the stegoed files and is discussed in the second research project. The artifacts discussed in the first research project are specific only to the images. The embedding action of the algorithms often leaves image artifacts in the cover images ("Stego Suite," 2006). These algorithms act in known and predictable ways. The algorithms which are used for hiding information in the carrier files use different techniques to hide information in different types of files. Various techniques of steganography include LSB (least significant bit) steganography (Wayner, 2002), manipulation of the Discrete Cosine Transform (DCT) function (Acharya and Tsai, 2005), and the append technique (Goudy, 2007). The resultant files which contain the hidden information are referred to as stegoed files. The images in which the secret information is hidden are called carrier files or cover images. Steganography can be hidden within numerous types of files, most commonly image files. Steganography facilitates secret, undetected communication and refers to hiding information in information (Katzenbeisser and Petitcolas, 2000). The term steganography can also be used to refer to the hidden information itself. Steganography is the art and science of hiding information. The term steganography is derived from the Greek words steganos, which means 'covered', and graphein, which means 'to write' (Singh, 1999). Keywords: steganography, signature detection, file artifact detection. Thus, the contribution of the research was in demonstrating that the limitations of the tools based on the signature detection of steganographically altered images can be overcome by focusing the detection effort on detecting the artifacts of the steganography-producing tools. The results demonstrated that the problem of 'the detection of the usage of steganography' could be addressed by the approach adopted after the research redirection and that certain steganographic software was popular among the criminals. As a proof of concept, a sample set of criminal computers was scanned for the remnants of steganography-producing software. This approach was based on the concept of 'Stego-Usage Timeline'. the images, to the 'artifacts' left by the steganography-producing software while it is being used to generate steganographic images. Thus, a redirection was introduced in the methodology and the detection focus was shifted from the analysis of the 'product' of the steganography-producing software viz. The probable reasons included the growth and availability of large number of steganography-producing tools and the limited capacity of the detection tools to cope with them. The research failed to demonstrate that steganography was prevalent on the public Internet. A detection tool was used to analyze these images. Web crawling technology was used and images were downloaded from Web sites that were considered as likely candidates for containing information hidden using steganographic techniques. An attempt was made to determine if steganography was being used by criminals to communicate information. Bad actors passing information using steganography are of concern to the national security establishment and law enforcement. ![]() Steganography is the art and science of hiding information within information so that an observer does not know that communication is taking place.
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