Explained – ‘Steganography’ – Hide Data in Image, Audio and Video Files

Ever wondered to know how to hide secret data in image, audio and video files? Well, in this post I will take you through a concept called steganography using which, it is possible to hide your secret information in image files, songs or any other file of your choice. At the end of this post, you can also download free stegnographic tools and start hiding your data.

What is Steganography?

Steganography is a means of obscuring data where secret messages are hidden inside computer files such as images, sound files, videos and even executable files so that, no one except the sender and the receiver will suspect the existence of stealth information in it. Steganography may also involve the usage of cryptography where the message is first encrypted before it is concealed in another file. Generally, the messages appear to be something else such as an image, sound or video so that the transfer of secret data remains unsuspected.

The main advantage of steganography over other methods such as cryptography is that, it will not arose suspicion even if the files fall in the hands of a third party. Unlike cryptographic messages, stegnographic messages will no way attract the attention of a third party by themselves. Thus stegnanography has an upper hand over cryptography as it involves both encryption and obscurity.

HIDING DATA

Steganography in video files based on exploiting the YCbCr colour space: YCbCr or Y’CbCr is a family of colour spaces used as a part of the Color image pipeline in video and digital photography systems. YCbCr represents colours as a combination of three values:

Y=The luminosity (roughly the brightness)
Cb=The chrominance (roughly colour) of the blue primary
Cr=The chrominance (roughly colour) of the red primary (Green is achieved by using a combination of these three values)

This technique is based on YCbCr. YCbCr space that can remove the correlation of R, G and B in a given image, as less correlation between colours means less noticeable distortion. In this study they concentrate on human video images, more specifically on human skin tones or colours for  data hinding. note that human skin colour can range from almost black to nearly colourless-appearing reddish white due to the blood vessels under the skin-in different people. The objective of this study is to combat the use of forged passport documents or national identity cards, a security measure would be to embed individuals’ information in their photos

What are the Applications of Steganography?

Steganography is mainly used to obscure confidential information/data during storage or transmission. For example, one can hide a secret message in an audio file and send this to another party via email instead of sending the message in the textual format. The receiver on the other end will decrypt the hidden message using the private decryption key. In a worst case scenario, even if a third party does manage to gain access to the email, all he can find is the audio file and not the hidden data inside it. Other usage of steganography include digital watermarking of images for reasons such as copyright protection.

Even though steganography has many useful applications, some may use this technique for illegitimate purposes such as hiding a pornographic content in other large files. Rumors about terrorists using steganography for hiding and communicating their secret information and instructions are also reported. An article claiming that, al-Queda had used steganography to encode messages in images and transported them via e-mails, was reported by New York Times, in October 2001.

 

How do Steganography Tools Work?

Stegnography tools implement intelligent algorithms to carefully embed the encrypted text messages or data inside other larger files such as an image, audio, video or an executable file. Some tools will embed the encrypted data at the end of another file so that there will be enough room for storing larger data.

 

References: GoHacking

 

Please feel free to write your comments, suggestions or corrections.

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