What is Steganography?
Steganography is the technique of hiding information within non-secret data or files. This gets done to avoid detection or to maintain the secrecy of data or information. The basic idea behind steganography gets concealing any type of information within another file. For example, the file might be a video, image, audio clip, etc. The data gets later extracted to its supposed destination. It is the art and science of embedding secret messages in the cover message. This gets done in a way that no one, except sender and receiver, suspects the existence of the message.
Steganography is different from cryptography. But if both put together can result in improved security of protected data or information. The use of both together takes an extra step to secure or protect the information. This gets done so even the intruder will not get to know the secret data or information. Unlike cryptography, which secures data by transforming it into another unreadable format, steganography makes data invisible by hiding (or embedding) them in another piece of data. Thus cryptography is the science of overt secret writing while steganography is covert secret writing. The cover, host, or carrier is the target media in which information gets hidden so that other people will not notice the presence of the information.
The modified cover, including the hidden data, is referred to as a stego-object which can be stored or transmitted as a message. The secret information can be embedded in various types of cover. If information is embedded in a cover text file, the result is a stego-text object. It is possible to have cover audio, video, and image for embedding which result in stego-audio, stego-video, stego-image Nowadays, the combinations of steganography and cryptography methods are also used to ensure data confidentiality and to improve information security.
Types of Steganography
Text Steganography
It is nothing but hiding information inside the text files. It involves changing the format of existing texts or changing words within a text. Steganography also involves generating random character sequences and using some sort of context-free grammar. There are a lot of ways in which data get hidden within texts. Some include format based methods, random and statistical generation, linguistic methods, etc.
Image Steganography
Image steganography involves hiding data within an image. It is one of the most popular ways of hiding data. This is because, in the image, there is a huge number of bits present in the digital representation. So, it becomes easier to hide the data within an image. There are a lot of ways in which data gets hidden within an image. For example, LSB steganography, masking and filtering, and many others.
Audio Steganography
The audio steganography consists of Carrier or Audio file, Message, and Password. Carrier is also known as a cover-file, which conceals the secret information. In the steganography model the secret message that the sender sends wants to remain in secret. Message can be of any type may be text, image, audio, or any type of file, .in secret stego key which only the receiver knows the corresponding decoding key will be able to extract the message from a cover-file. The cover file with the secret information is known as a stegofile.
Steganography vs Cryptography
Cryptography encrypts the message and that helps in hiding the content of the message. So, after encryption, the content of the message is not visible. This provides security but the attacker can crack the code and interpreted the message. So, adding a new layer of security cryptography along with steganography is the best option. If an attacker found that a steganographic image has a message then also he will get an encrypted message, not the original one. The combination of both makes the communication more secure and robust.
Algorithm of the combination technique:-
1] The sender will provide the plain text and a key
2] Then an algorithm is used for encryption of the
message.
3]Then this encrypted message or ciphertext is
embedded in an image with the help of some
algorithm to produce a Stegano Image and key is
option in this process.
4]Then the Stegano image is transmitted for
communication.
5] Then the receiver will perform the reverse processes.
The receiver will first extract the Cipher message form
image using extraction algorithm.
6] Then the receiver will apply a decryption algorithm and
will provide a key to decrypt the ciphertext.
7] The output will be the original plain text message.
