Image Steganography using Stegosuite in Linux

With the rapid growth of network bandwidth and digital-communication techniques, the Internet is available to the majority of the population and it also becomes the common channel for transmitting many documents—for instance, video, image, text, and audio (in digital form). Many practices and methods have been developed to make the transmission of data more secure. The problem is that the focus of the current research is mainly on the better designing of data-hiding techniques used for transmitting secret data where digital images are selected as the cover-media. Unlike the other forms of communication, the process of steganography is defeated when the communication between sender and receiver is detected. Therefore, the first requirement for a good steganographic structure is it is undetectable.   

Hiding secret information in Audio and Images:

Many methods for hiding information in audio and images exist. These methods may include hiding information in unused space in file headers to hold "extra" information. Embedding techniques can range from the placement of indistinguishable information level, sometimes it includes manipulation of compression algorithms, and to the extent of modification of properties of the carrier. In audio file Steganography, small echoes or slight delays can be added or indistinct signals can be masked by sounds of higher amplitude.

Stegosuite:

Stegosuite is a graphical steganography tool (this is the main difference between Stegosuite and Stegohide). It is used to hide secret data or information in image files. Stegosuite provides the facility of embedding text messages and multiple files of any type.  To make the process of embedding more secure, the embedded data is encrypted using AES (Advanced Encryption Standard). Currently, the Stegosuite tool supports BMP, GIF, JPG, and PNG file types.  

Installing Stegosuite:

To install the Stegosuite tool in Kali Linux follow the below commands. 

sudo apt-get update -y

// Execute above command  first then execute 
// next command to avoid Archives 
// Installation Error
sudo apt-get install stegosuite

Now after complete execution of the above commands. To run Stegosuite simply type “stegosuite” in  terminal.

stegosuite

Embed data:

1. stegosuite command will open the Stegosuite window.
2. Click on the file in the Stegosuite window to select the image file.
3. Type the secret message or select the text files you want to embed in the image.
4. Choose any password and after that click on the Embed button.

In the above image, We are hiding a secret message as well as a text file. Then we just need to click on Embed and Steganography will be done.

Extract Data:

1. Click on the file in Stegosuite window to select the stego file you want to extract hidden information from
2. Type the password and click the extract button
3. The hidden data will be extracted

Type your Password and click on Extract. The hidden message and text files will be visible now. 

Techniques of image steganography:

Image steganography is a process of hiding information within an image. Some of the common techniques used to implement image steganography are as follows:

1. Least Significant Bit Substitution:

• Approach: Modify the least significant bits of pixel values to encode the secret itself.
• How it works: Considering an 8-bit color image, take the least significant bit of each color component (Red, Green, Blue) for holding bits of the secret message. Say we take a pixel value, `10110011`, and change the least significant bit to `10110010`; the image would be approximately the same.

2. Masking and Filtering:

• Method: Masking techniques that disguise the data in the important parts of the image or in filters.
• How it works: An image is overlaid with a mask or filter that holds the secret information, and changes become unnoticeable. Usually used in conjunction with other methods.

3. Transform Domain Techniques:

• Method: Embedding of secret data is done in the frequency domain of output image rather than in spatial domain.
• How it works: The method in which secret data is embedded is any transformation like DCT or DWT is used for embedding the secret data. It possibly can provide better Compression and noise robustness.

4. Palette-based Techniques:

• Method: Perform manipulation of the color palette in an indexed color image.
• How it works: In images providing a palette, typically GIFs, the secret information is embedded using the modification of the color palette entries, which could be barely visible.

5. Image Substitution:

• Method: Replace a piece of an image with another containing hidden information.
• How it works: Embedding secret data in an image segment by its replacement with another image segment, which, at the same time, has to stay perceptually near the original segment.

6. Redundant Pixel Encoding:

• Method: Utilizes redundancy in data of the source image.
• The way it functions: Embed the secret data in the redundant pixels or certain patterns of the cover image by modifying and encoding it. Observe to keep the changes minimal and less perceptible.

Each technique has different advantages and limitations, and the choice of method depends on the requirements for imperceptibility, capacity, and robustness against attacks.

Real-world applications of steganography:

Steganography is used in almost all areas of the following applications:

1. Secure Communication:

• Usage: Hiding of secret messages in any form of multimedia to avoid secret accesses.
• Example: Hiding a text message in any form of image, audio, video, etc., so that it looks unsuspicious and cannot be read or played by anybody who should not read or hear it.

2. Digital Watermarking:

• Usage: It involves the concealing of some information in images and videos to make the ownership safe and secure against unauthorized purposes.
• Example: Digital art inside which the copyright authenticity mark will be embedded.

3. Authentication:

• Application: Implanting hidden codes in documents or images to unambiguously verify the veracity of the source.
• Example: Hiding a unique code inside a document to check its source's authenticity.

4.Covert Operations:

• Application: Hidden in any other data to obviate detection.
• Example: Hiding sensitive data inside any digital file to prevent its interception.

5. Data Integrity:

• Usage: Provide hidden data to verify that data has not been edited or tampered with.
• Example: Software update in which you can embed a hidden signature to ensure no one has tampered with it.

These applications help assure privacy, protect intellectual property, and secure sensitive communications.

Conclusion

Steganography in an image using Stegosuite under Linux is the easiest way to hide data within an image. The utility provides a clear interface both to embed and extract the hidden message; therefore, this may be one of the tools helpful for all people interested in secure communications and protection of their private data. It is versatile with respect to processing a large number of image formats and has a very straightforward approach—which makes it a valuable tool for everyone interested in digital steganography.