Audieo Steg

AUDIO STEGANOGRAPHY

Sanket Sheth Dept. of Computer Engineering, K.J. Somaiya College Of Engineering, Institute (Mumbai). [email protected]

Abstract: The main purpose of steganography is to hide the occurrence of communication. While most methods in use today are invisible to the observer's senses, mathematical analysis may reveal statistical discrepancies in the steganographic medium. These discrepancies expose the fact that hidden communication is happening. This paper presents a new method to preserve the statistical properties of the cover medium in the field of music. After applying a correcting transform to a music file, statistical steganalysis is no longer able to detect the presence of steganography. To evaluate the effectiveness of my approach, I present tests for the JPEG image format initially and follow it with MP3 format to explain how the new method works.

Keywords: Steganography Steganalysis

FORMULA USED FOR STEGANOGRAPHY: The following formula provides a very generic description of the pieces of the steganographic process: cover_medium + hidden_data + stego_key = stego_medium In this context, the cover_medium is the file in which we will hide the hidden_data, which may also be encrypted using the stego_key. The resultant file is the stego_medium (which will, of course. be the same type of file as the cover_medium). The cover_medium (and, thus, the stego_medium) are typically image or audio files.

AUDIO STEGANOGRAPHY ENCODING AND DECODING: To encode, following syntax is used: encode –E secret_text.txt –P passphrase sanket.wav sanket1.mp3 This compresses sanket.wav along with secret_text.txt into sanket1.mp3, encrypting the hidden text using the passphrase “passphrase.” Decoding the file is accomplished using: Decode –X –P passphrase sanket1.mp3 This uncompresses sanket1.mp3 into sanket1.mp3.pcm and decrypts and saves the hidden text as sanket1.mp3.txt

IMAGE STEGANOGRAPHY: Images typically use either 8-bit or 24-bit color. When using 8-bit color, there is a definition of up to 256 colors forming a palette for this image, each color denoted by an 8-bit value. A 24-bit color scheme, as the term suggests, uses 24 bits per pixel and provides a much better set of colors. In this case, each pix is represented by three bytes, each byte representing the intensity of the three primary colors red, green, and blue (RGB), respectively. The Hypertext Markup Language (HTML) format for indicating colors in a Web page often uses a 24-bit format employing six hexadecimal digits, each pair representing the amount of red, blue, and green, respectively. The color orange, for example, would be displayed with red set to 100% (decimal 255, hex FF), green set to 50% (decimal 127, hex 7F), and no blue (0), so we would use "#FF7F00" in the HTML code. GIF and 8-bit BMP files employ what is known as lossless compression, a scheme that allows the software to exactly reconstruct the original image. JPEG, on the other hand, uses lossy compression, which means that the expanded image is very nearly the same as the original but not an exact duplicate. While both methods allow computers to save storage space, lossless compression is much better suited to applications where the integrity of the original information must be maintained, such as steganography. While JPEG can be used for stego applications, it is more common to embed data in GIF or BMP files. The simplest approach to hiding data within an image file is called least significant bit (LSB) insertion. In this method, we can take the binary representation of the hidden_data and overwrite the LSB of each byte within the cover_image. If we are using 24-bit color, the amount of change will be minimal and indiscernible to the human eye. As an example, suppose that we have three adjacent pixels (nine bytes) with the following RGB encoding: 10010101 00001101 11001001 10010110 00001111 11001010 10011111 00010000 11001011

Now suppose we want to "hide" the following 9 bits of data (the hidden data is usually compressed prior to being hidden): 101101101. If we overlay these 9 bits over the LSB of the 9 bytes above, we get the following (where bits in bold have been changed): 10010101 00001100 11001001

10010111 00001110 11001011 10011111 00010000 11001011

Note that we have successfully hidden 9 bits but at a cost of only changing 4, or roughly 50%, of the LSBs.

Without going into any detail, it is worth mentioning steganalysis, the art of detecting and breaking steganography. One form of this analysis is to examine the color palette of a graphical image. In most images, there will be a unique binary encoding of each individual color. If the image contains hidden data, however, many colors in the palette will have duplicate binary encodings since, for all practical purposes, we can't count the LSB. If the analysis of the color palette of a given file yields many duplicates, we might safely conclude that the file has hidden information.

Audio Steganography : •

SOFTWARE REVIEW:

Now let us review one of the many available steganography tools. The software going to be reviewed is named STEGANOGRAPHY.

The above is the first window you will see when you open the software. It is quite selfexplanatory. One has to select a carrier by clicking on the picture button alongside the Step 1.For audio steganography, one can select any audio file (.wav, .mp3 etc.) Then one has to add message or a file by selecting the appropriate option after clicking on Add button.

On selecting File one has to select a file from the file browser. If one selects message option then a window opens as shown below:

One can enter the message in the space provided. Then enter password twice to complete the input details. Then clicking on hide opens the file browser again asking the file name for saving the file(with same extension as the carrier file).Now the file is ready with secret data to be sent without any trace of the same.

Now retrieving the file is also very simple. Simply specify the carrier file having the data. Then enter the password required to unhide the files. On clicking UNHIDE button one will see the files which were added to be retrieved which can be saved by double clicking on file name.

Double clicking on message opens a window with the message as shown below

Thus one can save the message as a txt file.

FUTURE PROSPECT: The fact that steganography cannot be detected at all times makes steganalysis an area of ongoing research. The limitations are magnified due to the fact that steganography is not an exact technique. Today’s steganographic programs can hide any type of binary data into various types of cover media. One can never predict whether there is a secret message to begin with; it’s much like looking for needles in haystack! The use of steganography by terrorists and criminals is likely to increase in the future, posing a problem for law enforcement agencies. Steganalysis needs to be further developed to help counter high tech terrorism and cases of industrial espionage. Apart from the law enforcement/intelligence and anti-terrorist significance, audio steganographic techniques also have peaceful applications, including: in-band captioning; integration of multiple media for convenient and reliable storage, management, and transmission; embedding executables for function control; error correction; and version upgrading. Computer specialists, signal-processing researchers, and information security professionals should expect to devote much more attention to the challenging area of information hiding and detection.

CONCLUSION : Steganography techniques involving audio file formats appear to be increasing in popularity. This may be attributed to the fact that current steganalysis tools available to the general public fall short when applied to audio files. Another factor that may be contributing to the increasing popularity is the widespread popularity of the MP3 file format and its ubiquitous presence on storage media and the Internet. Only adding to the appeal of audio steganography is the relatively large size of MP3 files. These large files make detection of stegotext more difficult. In conclusion, as more emphasis is placed on the areas of copyright protection, privacy protection, and surveillance, I believe that steganography will continue to grow in importance as a protection mechanism. Audio steganography in particular addresses key issues brought about by the MP3 format, P2P software, and the need for a secure broadcasting scheme that can maintain the secrecy of the transmitted information, even when passing through insecure channels.

Steganography techniques involving audio file formats appear to be increasing in popularity. This may be attributed to the fact that current steganalysis tools available to the general public fall short when applied to audio files. Another factor that may be contributing to the increasing popularity is the widespread popularity of the MP3 file format and its ubiquitous presence on storage media and the Internet. Only adding to the appeal of audio steganography is the relatively large size of MP3 files. These large files make detection of stegotext more difficult which make them suitable candidates as carrier files. [Note: This paper can be downloaded from http://sanketsheth.info/publications.html]

REFERENCES : 1. http://www.snotmonkey.com/work/school/405/methods.html#evalFirefoxHTM L\Shell\Open\Command 2. SOFTWARE RESOURCE: http://www.securekit.com