Understanding Steganography Technologies
Steganography is the
process of hiding data in other types of data such as images or text
files. The most popular method of hiding data in files is to utilize
graphic images as hiding places. Attackers can embed any information in a
graphic file using steganography. The hacker can hide directions on
making a bomb, a secret bank account number, or answers to a test. Any
text imaginable can be hidden in an image. In Exercise 4.3 you will use Image Hide to hide text within an image.
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ImageHide is a steganography
program that hides large amounts of text in images. Even after adding
bytes of data, there is no increase in the image size. The image looks
the same in a normal graphics program. It loads and saves to files and
therefore is able to bypass most email sniffers.
Blindside is a steganography application that hides information inside BMP (bitmap) images. It's a command-line utility.
MP3Stego hides information
in MP3 files during the compression process. The data is compressed,
encrypted, and then hidden in the MP3 bitstream.
Snow is a whitespace
steganography program that conceals messages in ASCII text by appending
whitespace to the end of lines. Because spaces and tabs generally aren't
visible in text viewers, the message is effectively hidden from casual
observers. If the built-in encryption is used, the message can't be read
even if it's detected.
CameraShy works with Windows
and Internet Explorer and lets users share censored or sensitive
information stored in an ordinary GIF image.
Stealth is a filtering tool for
PGP files. It strips off identifying information from the header, after
which the file can be used for steganography.
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To hide data in an image using ImageHide:
Download and install the ImageHide program.
Add an image in the Image Hide program.
Add text in the field at the bottom of the ImageHide screen.
Hide the text within the image using ImageHide.
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Steganography can be
detected by some programs, although doing so is difficult. The first
step in detection is to locate files with hidden text, which can be done
by analyzing patterns in the images and changes to the color palette.
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Stegdetect is an automated
tool for detecting steganographic content in images. It's capable of
detecting different steganographic methods to embed hidden information
in JPEG images.
Dskprobe is a tool on the Windows 2000 installation CD. It's a low-level hard-disk scanner that can detect steganography.
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