STEGANOGRAPHY
Steganography is one method used to secure the transmission of confidential information. After the
application of the steganography method the resulting output file is called a stego-object.
Unintentional attacks usually include common data manipulations such as lossy compression,
digital-to-analog conversion, resampling, requantization, etc.
Here the data secret is being embedded inside the cover image to generate the image stego. Keys are
often needed in the planting process.
In the modern approach, depending on the nature of the object covering, steganography can be
divided into five types:
• Text Steganography: Text steganography can be achieved by changing the format of the text, or by
changing certain characteristics of the textual elements (eg, this includes lineshift coding, word
changing and feature coding.
The different algorithms used are least significant bit insertion, Masking and filtering, Redundant
Pattern Encoding, Encryption and Scattering, Algorithm and transformation.
• Video Steganography: Video files are generally collections of images and sound, so most of the
techniques presented on images and audio can be applied to video files as well. The great advantages
of video are the huge amount of data that can be hidden inside and the fact that it is a moving stream
of pictures and sound.
• Uses of Steganography: The three most popular and researched uses for steganography in open
systems environments are confidential channels, embedded data and digital watermarks.
STEGANOGRAPHY METHOD
The following formula gives a very general description of the part of the steganographic process:
cover_medium + hidden_data + stego_key = stego_medium In this context, cover_medium is the file
we will hide hidden_data, which can also be encrypted using the stego_key.
The resulting file is stego_medium (which of course will be the same file type as cover_medium).
Cover_medium (and, thus, stego_medium) is usually an image or audio file.
In this article, I will focus on image files and will therefore refer to cover_image and stego_image.
Before discussing how information is hidden in image files, it's worth a quick review of how images
are stored in the first place.
An image file is simply a binary file that contains a binary representation of the color or light intensity
of each image element (pixel) that the image consists of.
When using 8-bit color, up to 256 colors make up the palette defined for this image, each color is
denoted by an 8-bit value. GIF and 8-bit BMP files use what is known as lossless compression, this
scheme allows the software to precisely reconstruct the original image.
If we overlay these 9 bits over the LSB of the 9byte above, we get the following (where the bits in
bold have changed): 10010101 00001100 11001001 10010111 00001110 11001011 10011111
Steganography is one method used to secure the transmission of confidential information. After the
application of the steganography method the resulting output file is called a stego-object.
Unintentional attacks usually include common data manipulations such as lossy compression,
digital-to-analog conversion, resampling, requantization, etc.
Here the data secret is being embedded inside the cover image to generate the image stego. Keys are
often needed in the planting process.
In the modern approach, depending on the nature of the object covering, steganography can be
divided into five types:
• Text Steganography: Text steganography can be achieved by changing the format of the text, or by
changing certain characteristics of the textual elements (eg, this includes lineshift coding, word
changing and feature coding.
The different algorithms used are least significant bit insertion, Masking and filtering, Redundant
Pattern Encoding, Encryption and Scattering, Algorithm and transformation.
• Video Steganography: Video files are generally collections of images and sound, so most of the
techniques presented on images and audio can be applied to video files as well. The great advantages
of video are the huge amount of data that can be hidden inside and the fact that it is a moving stream
of pictures and sound.
• Uses of Steganography: The three most popular and researched uses for steganography in open
systems environments are confidential channels, embedded data and digital watermarks.
STEGANOGRAPHY METHOD
The following formula gives a very general description of the part of the steganographic process:
cover_medium + hidden_data + stego_key = stego_medium In this context, cover_medium is the file
we will hide hidden_data, which can also be encrypted using the stego_key.
The resulting file is stego_medium (which of course will be the same file type as cover_medium).
Cover_medium (and, thus, stego_medium) is usually an image or audio file.
In this article, I will focus on image files and will therefore refer to cover_image and stego_image.
Before discussing how information is hidden in image files, it's worth a quick review of how images
are stored in the first place.
An image file is simply a binary file that contains a binary representation of the color or light intensity
of each image element (pixel) that the image consists of.
When using 8-bit color, up to 256 colors make up the palette defined for this image, each color is
denoted by an 8-bit value. GIF and 8-bit BMP files use what is known as lossless compression, this
scheme allows the software to precisely reconstruct the original image.
If we overlay these 9 bits over the LSB of the 9byte above, we get the following (where the bits in
bold have changed): 10010101 00001100 11001001 10010111 00001110 11001011 10011111
