Read the text and match the paragraphs with their headings. Arrange the paragraphs in the correct order.

1) What is steganography used for? 2) Security Focus. 3) Steganography tools. 4) Steganography and security. 5) What is Steganography?

a) __________ Like many security tools, steganography can be used for a variety of reasons, some good, some not so good. Legitimate purposes can include things like watermarking images for reasons such as copyright protection. Digital watermarks (also known as fingerprinting, significant especially in copyrighting material) are similar to steganography in that they are overlaid in files, which appear to be part of the original file and are thus not easily detectable by the average person. Further, steganography can be used to tag notes to online images (like post-it notes attached to paper files). Finally, steganography can be used to maintain the confidentiality of valuable information, to protect the data from possible sabotage, theft, or unauthorized viewing. Unfortunately, steganography can also be used for illegitimate reasons. For instance, if someone was trying to steal data, they could conceal it in another file or files and send it out in an innocent looking email or file transfer. And, as was pointed out in the concern for terroristic purposes, it can be used as a means of covert communication. Of course, this can be both a legitimate and an illegitimate application.

b) __________ There are a vast number of tools that are available for steganography. An important distinction that should be made among the tools available today is the difference between tools that do steganography, and tools that do steganalysis, which is the method of detecting steganography and destroying the original message. Steganalysis focuses on this aspect, as opposed to simply discovering and decrypting the message, because this can be difficult to do unless the encryption keys are known.

c) __________ As mentioned previously, steganography is an effective means of hiding data, thereby protecting the data from unauthorized or unwanted viewing. But stego is simply one of many ways to protect the confidentiality of data. It is probably best used in conjunction with another data hiding method. When used in combination, these methods can all be a part of a layered security approach. Some good complementary methods include:

Encryption — Encryption is the process of passing data or plaintext through a series of mathematical operations that generate an alternate form of the original data known as ciphertext. The encrypted data can only be read by parties who have been given the necessary key to decrypt the ciphertext back into its original plaintext form. Encryption doesn’t hide data, but it does make it hard to read!

Hidden directories (Windows) — Windows offers this feature, which allows users to hide files. Using this feature is as easy as changing the properties of a directory to “hidden”, and hoping that no one displays all types of files in their explorer.

Hiding directories (Unix) — in existing directories that have a lot of files, such as in the /dev directory on a Unix implementation, or making a directory that starts with three dots (...) versus the normal single or double dot.

Covert channels — Some tools can be used to transmit valuable data in seemingly normal network traffic. One such tool is Loki. Loki is a tool that hides data in ICMP traffic (like ping).

d) __________ While we are discussing it in terms of computer security, steganography is really nothing new, as it has been around since the times of ancient Rome. According to Dictionary.com, steganography (also known as “steg” or “stego”) is “the art of writing in cipher, or in characters, which are not intelligible except to persons who have the key; cryptography”. In computer terms, steganography has evolved into the practice of hiding a message within a larger one in such a way that others cannot discern the presence or contents of the hidden message. In contemporary terms, steganography has evolved into a digital strategy of hiding a file in some form of multimedia, such as an image, an audio file (like a .wav or mp3) or even a video file.

e) __________ Over the past couple of years, steganography has been the source of a lot of discussion, particularly as it was suspected that terrorists connected with the September 11 attacks might have used it for covert communications. While no such connection has been proven, the concern points out the effectiveness of steganography as a means of obscuring data. Indeed, along with encryption, steganography is one of the fundamental ways by which data can be kept confidential.

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Work in pairs. Find out how often and how your partner backups the data. Would he use the services of Carbonite? Report the results to the class.	\|	V. Talk about yourself, your family, and your friends.

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