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While Encryption Steganography I. INTRODUCTION While Encryption is detectable and a target for questions by the government as well as hackers, Steganography takes it one step further and hides the message within an encrypted message or other mediums; such as images, making it virtually impossible to detect. It is a method related to the art of hiding a secret message within a larger one in such a way that the unwanted person cannot make out the presence or contents of the hidden message being sent. It can be hidden in a picture or a sound file. Most communication channels like telephone lines and radio broadcasts transmit signals, which are always followed by some kind of, noise.
This noise can be replaced by a secret signal that has been changed into a form that is not detectable from noise without knowledge of a secret key and this way, the secret signal can be transmitted undetectable. [ 1 ] A. Purpose of this paper The purpose of this paper is to introduce steganography by explaining what it is and how it works in conjunction with cryptography; provide a brief history; note on the types of software programs available and how effective they are. B. Body First, I will define stenography, along with cryptography and digital watermarking.
I will also discuss the differences between the two. Second, I will discuss briefly the history of steganography. Finally, I will review several different software applications available that provide steganography, how they are implemented and discuss any failures that may occur. C.
Conclusion I will review the topics, which were discussed and give my personal opinion on a particular software programs that I tried out. II. STEGANOGRAPHY A. Definition Steganography comes from the Greek word Steganos meaning covered or secret, basically hidden writing. Steganography is a non-cryptographic technique for hiding data in the natural noise component of some other signal. Steganography simply takes one piece of information and hides it within another.
It uses computer files (images, sounds recordings, even disks) which contain unused or insignificant areas of data. Invisible inks, microdots, character arrangement, digital signatures, covert channels, and spread spectrum communications also use Steganography. Steganography takes advantage of these areas, replacing them with information (encrypted mail, for instance). The least significant bits (LSBs) of most digitized signals; music or images for instance; are randomly distributed. You can change these bits to anything you like without noticeably changing the music or images.
Cryptography disguises the text of the message but doesn? t hide the fact that it is doing so. PGP (Pretty Good Privacy), a very strong cryptographic tool. Its popularity doesnt stem from the fact that nobody knows how to break the system other than by a brute-force attack (which is a prerequisite for any good crypto system). PGP became popular because it is extremely well designed, fast, and has an excellent key management. There are many cryptographic algorithms as strong as the one used in PGP, but Pgp's popularity and free availability made it a de facto standard for secure electronic communications all over the world. [ 2 ] Digital watermarking which is a special technique of creating invisible digital marks in images and audio files that carry copyright information.
These marks can be detected by special programs that can derive a lot of useful information from the watermark: when the file was created, who holds the copyright, how to contact the author etc. As you know tons of copyrighted materials are reproduced, i. e. stolen on the Net every day so this technology might be useful if you are a designer. B.
History Steganography dates back to ancient Greece. During ancient Greek wars, if a solder needed to notify his leader that he had information on enemies planning to attack at a certain place and time, he would take a blank tablet write the message then cover the tablet with wax. This was a way to conceal the information as he passed through inspections. [ 3 ] Another way they used to send hidden messages was to shave the messenger? s head then tattoo the information. Once his hair had grown enough to cover the message, he was then sent on his way to deliver the message. Of course, he had to have his hair shaved again for the message to be revealed then let his hair grow back.
During World War II, the Germans developed the microdot. A secret message was photographically reduced to the size of a period, and affixed as the dot for the letter i or other punctuation on a paper containing a written message. Microdots permitted the transmission of large amounts of printed data, including technical drawings, and the fact of the transmission was effectively hidden. Another form of hiding information was using Null ciphers (unencrypted messages).
The real message is " camouflaged" in an innocent sounding message. Due to the " sound" of many open coded messages, mail filters detected the suspect communications. However " innocent" messages were allowed to flow through. An example of a message containing such a null cipher is: News Eight Weather: Tonight increasing snow. Unexpected precipitation smothers eastern towns.
Be extremely cautious and use showtimes especially heading east. The highways are knowingly slippery. Highway evacuation is suspected. Police report emergency situations in downtown ending near Tuesday.
By taking the first letter in each word, the following message can be derived: Newt is upset because he thinks he is President. The following message was actually sent by a German Spy in WWII [Kahn 67 ]: Apparently neutrals protest is thoroughly discounted and ignored. Island hard hit. Blockade issue affects pretext for embargo on by products, ejecting suet's and vegetable oils. Taking the second letter in each word the following message emerges: Pershing sails from NY June 1.
Recently, Margaret Thatcher was so irritated with numerous press leaks of cabinet documents, she had the word processors programmed to encode their identity in the word spacing, so that disloyal ministers could be traced. [ 4 ] C. Software Three types of stegonagraphic software packages were evaluated by Neil Johnson and Sushi Jajodia (authors of Exploring Steganography: Seeing the Unseen) on their limitations and flexibility. [ 5 ] They are Stegodos, White Noise Storm and S-Tools for Windows. Stegodos is a share-ware program, which can be downloaded for free off the internet (web). Its limitation is that it only works with 320 x 200 -pixel images with 256 colors.
Using a Renoir painting, they tried to insert a photo of the Russian strategic bomber base (web). It could not be used because of size restrictions. They were able to use the software in the Shakespeare image once it was cropped and fitted into the 320 x 200 pixel image. There was some distortion to the image but not very noticeable. Stegodos uses LSBs (Least Significant Bits) to hide it? s messages.
It is the less successful tool of the three tested. White Noise Storm is a DOS application and is very effective. It uses the LSB approach and applies this to IBM Paintbrush (PCX) files. They were able to embed the Russian strategic bomber base into the Renoir painting with no degradation to the image.
But, there were problems due to noise interference in the integrity of the image, which altered the color palette considerably in the Renoir painting. The main disadvantage of this encryption method is the loss of many bits that can be used to hold information. [ 5 ] The last software evaluated was S-Tools for Window. This freeware program lets you hide files of any type in. gif and. bmp images as well as in.
wav sounds. Furthermore, S-Tools is actually a steganography and cryptographic product in one, because the file to be hidden is encrypted using one of the symmetric key algorithms: Triple DES and IDEA are very secure as of today. Another good steganography product is Steganos for Windows 95. It has almost the same functions as S-Tools, but applies a different algorithm (HWY 1) and is able to hide data in. bmp and. wav files as well as in plain text and HTML files in a very clever way.
Steganos just adds a certain number of additional spaces at the end of each text line. Steganos also adds an option of sending files from your hard drive to the shredder, which makes it impossible to recover them. III. CONCLUSION In conclusion, I gave a brief definition of steganography as well as cryptography and digital watermarking. Next, I went into a little history about Steganography and where it originated.
Finally, I discussed some of the software that is available, what implementations were used and noted any limitations with those software programs. Steganography is much powerful tool when used in conjunction with cryptography because it adds another layer of protection to an encrypted file. Commercial applications of steganography, digital watermarking and digital fingerprinting is now in use to track the copyright and ownership of electronic media. [ 5 ] [ 1 ] Markus Kuhn, 1995 web [ 2 ] Introduction to PGP web [ 3 ] Mr. Byte, Steganography, 1997 - 1999 web [ 4 ] Anderson, Ross J. , Petitcolas, Fabien A. P. , On The Limits of Steganography 16 [ 4 ] 474 - 481, May 1998 [ 5 ] Johnson, Neil F. , Steganography, 26 - 34 web
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