Article Preview
Top1. Introduction
Steganography comes from the Greek words (στεγανό-ς, γραφ-ειν) meaning, “covered writing”. In the past, human used a hidden ink or concealed tattoos to transfer stegnographic messages. This day, data processor and internet technology supply simple to utilize different channels of communications for steganography (Agarwa, 2013; Provos & Honeyman, 2003).
Steganography is the science and art of concealing communications stenographic process, consequently hides the concealed contents in unnoticeable covering media, thus it will not induce the suspiciousness of eavesdroppers. Cryptography, in contra to, wherever the enemies are permitted to intercept, detect and update the contents without being capable to break a specific security promise ensured by a crypto-system. Steganography objectives are to conceal message into other safe media in a manner which doesn't let the enemies at all to notice that there are other messages (Dunbar, 2002; Changder et al., 2010a; Ammar et al., 2010; El Rahman, 2016; El Rahman et al., 2016). The steganography feature over just cryptography is the hidden content does not draw alertness to recipients, enemy, or messengers (Samphaiboon & Dailey, 2008; Ankit, 2007). A comparison between steganography and cryptography is presented in Table 1 (El Rahman, 2015).
Table 1. A comparison between steganography and cryptography (El Rahman, 2015)
Steganography used in many applications to contain secrete communication, whereas cryptographic encryption algorithms aren't obtainable and also, powerful cryptography is impractical. In several instances, for instance, in martial application, even the information which two parties communicate could be of great interest. Besides, in the healthcare, and particularly the systems of medical imaging, might extremely well-being from data hiding algorithms (Changder et al., 2009; Changder et al., 2010a).
Steganography techniques are in common (see Figure 1) established on substituting noisy components of a digital medium by hidden messages. The system Security must not be established on an embedding technique, but on concealing the key (Changder et al., 2010b).
Figure 1. Common steganography system model
The “Embedded” data is the data to be concealed in the cover media. The data include the cover media and the “embedded” data together is known as the “Stego” data. Reasonably, the procedures of embedding the embedded, or the hidden data into the cover media, is often known as embedding. The expression “cover” is utilized to characterize the innocent message, original, data, video, audio, and so on, as shown in Figure 2. The procedure could be symbolized by Equation (1) (Channalli & Jadhav, 2009):
Stego-Medium =
Embedded Message + Stego-Key + Cover Medium(1)