What is steganography? How to perform steganography without using any software

What is Steganography : 

It is the art of hiding secret message inside ordinary message (which has no meaning). Steganography is alternate to encryption. Steganography is the useful technique to achieve computer security or information security.

In encryption the message to be kept secret (which is in plaintext/readable format) is applied to encryption algorithm and as a result of encryption algorithm the plaintext message get converted into ciphertext (ciphertext is the text which is not readable and understandable) and transmitted to destination.

If there is a person who capture the transmission media and who is able to sniff the messages in transit then the secret message in ciphertext form may attract to that third person. Ciphertext are point of attractions since it don’t have meaning, so the ultimate aim of attacker is to understand the ciphertext.

The contents of secret message are in ciphertext (not readable and understandable) but attacker can perform various cryptanalysis technique to get original message in plain text form (readable and understandable). The process of cryptanalysis may be time consuming but attacker can be succeeded to obtain original message. The time required to perform cryptanalysis can be one minute, can be one hour, can be one day, or one week or month/s. The complexity of algorithm and key makes it difficult to an attacker to obtain plaintext from ciphertext.

Attacker tries to retrieve contents/patterns form ciphertext because the message is in ciphertext form (which creates curiosity).

On the other hand steganography is alternate to encryption, here the message to be kept secret is hided in some ordinary message which is not relate to secret message. The contents of secret message are kept hidden in ordinary message such that its presence is doesn’t noticed by attacker/unauthorised person. There should be a pattern which is used for hiding of secret message in ordinary message and this pattern will be known to only sender and receiver of that message. (These patterns can be the first letter of each word, first letter of each sentence, last letter of each word etc.)

Steganography can be performed on text as well as on images. Traditional steganography works with text, in which secret text message is hidden inside ordinary/cover text message. Modern steganograpy is based on digital, in which a secret text message (ASCII) hides inside another ordinary/cover message text, here both text message are in digital/binary form. In modern steganography a secret text message can be hide inside a image/picture as well as a secret image is hide inside other ordinary image file. So in modern steganography text, image, audio or video file can be used as cover/ordinary message.

Steganography Terminology

Secret media (secret message) – the message to be kept secret. Secret message generated at sender side. Secret message can be in the form of text, image.

Cover media (ordinary message) – the message which is irrelevent to secret message used to hide secret message. Cover media can be text, image, audio, video.

Stego key – the pattern used to hide secret message inside cover media.

Stego medium – combination of secret message, cover media and stego key is called stego media.

Stego media = secret message + cover media + stego key

How to perform Steganography using command prompt

In this article, how steganography can be performed is depicted, for this we need

• A computer with windows operating system and command prompt.
• A secret message in text format and stored in text file (in this experiment we use secret.txt as secret media)
• A cover media in which we have to hide secret.txt file. (in this experiment we use coverfile.jpg as cover file)

Ensure that these two files are stored at same location.

Open the command prompt and go to path/location where files are stored. Here files are kept at location D:\steg. Now we have to change the path for that I’m using following command cd

Create a archive file of secret message, for this go to the location where secret.txt is stored, Right click on Secret.txt (right click àSecret.txt à Add to Archive) and click on add to archive. This creates secret.rar 

After this to perform steganography we have to use utility command copy.

In command prompt type

                             “copy /b “secret.rar” + “Cover file.jpg” steg.jpg”

On the similar ground we type the following statement, where copy is utility command, /b is option/parameter with copy utility, secret.rar is secret.txt archived to secret.rar, coverfile.jpg is the ordinary image in which we have to hide secret message, and 123.jpg is stego medium in the form of jpg image

So we execute the statement and we get a new file at the same location named as 123.jpg

Stego file will be created in same folder

Here our task is finished in senders perspective, the created stego file is transmitted to destination and now receivers performs necessary operations to access secret file.

Send this file to the receiver.

At Receiver side receiver receives the file as 123.jpg, if receiver opens file then he finds a image/picture. In order to get secret message receiver needs to change extension of steg file (jpg to rar). In order to do this receiver first have to enable the “show extensions for known file type”. Right click on 123.jpg then click on rename and select extension portion jpg and replace it with rar. (123.jpg à Right Click à Rename àchange .jpg to .rar)

Now we get a file named with 123 and having extension rar. 

Now Right click on file 123.rar à click on extract here or extract to 123

If we click on extract here we get a file secret.txt and when we open this file we get the secret message that is sent by sender.