The art and science of writing hidden messages in such a way that no one, apart from the sender and intended recipient could understand or view is called Steganography.
According to Wikipedia, the word steganography is of Greek origin and means “concealed writing” from the Greek word steganos meaning “covered or protected” and graphei, meaning “writing”.
Steghide is a steganography program that is able to hide data in various kinds of image- and audio/files. The color respectivly sample frequencies are not changed thus making the embedding resistant against first-order statistical tests.
- Steghide application
- A .jpeg or .bmp file and a .txt file to hide within it
Straight from the Steghide website “Steghide is a steganography program that is able to hide data in various kinds of image- and audio-files. The color- respectivly sample-frequencies are not changed thus making the embedding resistant against first-order statistical tests”.
- Compression of embedded data
- Encryption of embedded data
- Embedding of a checksum to verify the integrity of the extracted data
- Support for Jpeg, Bmp, Wav and Au files
- Microsoft Windows
In my example I am going to use Microsoft Windows to hide some data in a text file called “secrettext.txt” in a file called “image.bmp” using Steghide version 0.5.1.
- Download Steghide
- Extract the application
- Copy the text and bmp file to the extracted location
- Drop to a command prompt
- Change to the directory the extracted application resides in
steghide.exe embed -ef secrettext.txt -cf image.bmp
- -ef = The text file you wish to encrypt
- cf = The image file you wish to encrypt the data in
Before encrypting the image it was 565,494 and after it was encrypted it is still 565,494. This makes it very hard to even detect that anything has been embedded within it.
You can also do this for audio files, the same process as above but use a Wav file.
Extracting the data is much the same as embedding it however you will need the following:
- Steghide Application
- The image/audio file
- The password
steghide.exe --extract -sf image.bmp -p password
The documentation for the application can be found here
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