Steganography
What is Steganography
Steganography is the practice of concealing a file, message, image,
or video within another file, message, image, or video.
Steganography is a technique of hiding the communication by
concealing the secret message into a fake message. The term steganography has
Greek influences which means “covered writing”. The
main idea behind the steganography is to prevent the suspicion about the
existence of the information.
Earlier,
invisible ink, pencil impressions on the handwritten characters, small pin
punctures are the methods used to hide the message. Simplest technique of
hiding a message is to create a message in which only a few significant characters
contains the secret message.
The steganography technique involves a cover carrier, secret
message, stego key and stego carrier. Text, audio, image and video behaves as
cover carriers which contain the hidden information embedded in it. Stego
carrier is generated using a cover carrier and embedded message. Stego key is
also used as supplementary secret information like a password used by the
recipient to extract the message.
Forms of steganography –
Text: In this steganography, the text can be used as a
cover media. To hide the message a word or line can be shifted; whitespaces can
be used, even the number and position of the vowels are utilised to conceal the
secret message.
Audio: Audio stenography can conceal the secret message in
the audio file with the help of its digital representation. It can be achieved
easily as a typical 16-bit file has 216 sound levels, and a few levels
difference could not be detectable by the human ear.
Video: Video steganography brings more possibilities of
disguising a large amount of data because it is a combination of image and
sound. Therefore, image and audio steganography techniques can also be employed
on the video.
Image: It is the most pervasively used form of
steganography, the reason behind this is that it causes least suspicion.
The main disadvantage of using the
steganography is a significant amount of overhead it produces for hiding a
small amount of information. Additionally, the system must not be discovered
otherwise it is useless.
Definition of Cryptography
The cryptography provides
several encoding schemes for achieving the security while communicating in a
public network. The word cryptography originated from a Greek word, which
signifies “secret writing”. The
cryptography can be understood by an example, where a sender sends a message
which initially exists in the plaintext. Before the transmission of the message
over the network, it is encrypted and converted into the ciphertext. When this
message is received at the receiver’s end, it is again decrypted back into the
plaintext.
Differences Between Steganography
and Cryptography
Key Differences Between Steganography and Cryptography
1.
The meaning of the steganography is “covered or hidden writing”
while cryptography signifies “secret writing”.
2.
Steganography is an attempt to achieve secure and undetectable
communication. On the other hand, cryptography intends to make the message
readable for only the target recipient but not by others through obtaining a
disguised form of message.
- In
steganography, the main structure of the message is not changed whereas
cryptography imposes a change on the secret message before transferring it
over the network.
- The
cryptography is prevalently used unlike steganography, which is not so
familiar.
- The
degree of the security of the secret data is measured by the key length
which makes the algorithm strong and unbreakable. Conversely, there is no
such thing in steganography.
- Steganography
provides only confidentiality and authentication. On the contrary, the
principles of security provided by the cryptography are confidentiality,
integrity, authentication, and non-repudiation.
- Spacial
domain, transform domain embedding and model-based are some of the
algorithms used in steganography. In contrast, the cryptography uses
techniques named as transpositional, substitution, stream and block
ciphers.
- The
steganography can be employed on any medium such as text, audio, video and
image while cryptography is implemented only on the text file.
- The reverse engineering employed to decode the message in cryptography is known as cryptanalysis. As against, the technique used to detect the presence of the steganography is known as steganalysis.
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