How To Hide Data In Images and Audio Files (Steganography)
Steganography is the art and science of hiding messages. Steganography is often combined with cryptography so that even if the message is discovered it cannot be read.The key difference between Cryptography and Steganography lies with the fact that when a message is encrypted, one already knows that the message exists and it is encrypted, whereas with Steganography you might not even know (or observe) that there does exists a message too, simply because its hidden behind an image, video or an audio etc… which without keen observation might go without any suspicion. Steganography was also widely used by the terrorists responsible for the 9/11 attacks at the twin towers, this was later figured out during the post attack investigation.
It is fairly easy to hide and then unhide a secret message in a graphic,audio or video file without obviously altering the visible appearance of that file.
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 is licensed under the GNU General Public License (GPL) which permits modification and distribution of the program as long as these modifications are made available to the public under the GPL.
In order to get started with hiding a text behind an Image, you need to first download Steghide from here. The software is available for Windows and Linux. For Windows package, After downloading unzip the contents of the zip file into a directory of your choice. You can use steghide from the command prompt.
1. Once you have unzipped and extracted the contents of Steghide, navigate to the command prompt.
2. Typing steghide at the command prompt gives you all the available options.
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| Image: Hiding Data Behind Images and Audio Files using Steghid |
C:\>steghide embed -cf picture.jpg -ef secret.txt
Enter passphrase:
Re-Enter passphrase: embedding “secret.txt” in “picture.jpg”… done
This command will embed the file secret.txt in the cover file picture.jpg.4. After you have embedded your secret data as shown above you can send the file picture.jpg to the person who should receive the secret message. The receiver has to use steghide in the following way:
C:\>steghide extract -sf picture.jpg
Enter passphrase:
wrote extracted data to “secret.txt”.
- If the supplied passphrase is correct, the contents of the original file secret.txt will be extracted from the stego file picture.jpg and saved in the current directory.
While Steghide is all about embedding and extracting (hidden) data from image and audio files, Steganography is also a lot about detecting whether a particular file contains any form of embedding or not. As the size and the quality of the image doesnt alter much, most of the files over the internet go without any suspicion. If you are looking out for a tool which can do the detection part as well, Stegdetect is an automated tool for detecting steganographic content in images. It is capable of detecting several different steganographic methods to embed hidden information in JPEG images.
