Image Steganography using clustering pattern matching & folding method -- 2

Because internet is a public environment, transmitted data are easy to be copied or destroyed by spies. Therefore, how to transmit data secretly by internet becomes an important topic. One of the main techniques of achieving this task is data encryption, which transforms data into a cipher text via cipher algorithms. Because cipher text look like a stream of meaningless codes, they easily attract grabbers, who may try to either recover them or simply destroy them. To overcome this problem, information hiding offers different approaches to transmitting secret data. Steganography is a technique to hide information from the observer to establish an invisible communication [1]. Information hiding is a method of embedding secret messages into multimedia data, such as images, videos, or movies, such that an unauthorized user will not be aware of the existence of the hidden messages. Steganography differs in the sense that where cryptography focuses on keeping in the contents of a message secret, steganography focuses on keeping the existence of a message secret . Steganography and cryptography are both ways to protect information from unwanted parties but neither technology alone is perfect and can be compromised. Once the presence of hidden information is revealed or even suspected, the purpose of steganography is partly defeated. The strength of steganography can thus be amplified by combining it with cryptography. Steganography focuses on the imperceptibility and the robustness of secret message. Human can barely feel the distinction between the embedded host signal and the original cover signal. So, the un detectability is assured.