Study and Analysis of Various Image Steganography Techniques

Steganography is the technique of hiding some data from the knowledge of an unwanted source inside some innocent looking canvas. When a steganographic system is developed, it is important to consider what the most appropriate cover work should be, and also how the stegogramme is to reach its recipient. In the last few years, we have seen many new and powerful steganography techniques reported in the literature. This paper gives the description of various techniques used in steganography. Different applications have different requirements of the steganography technique used. For example, some applications may require absolute invisibility of the secret information, while others require a larger secret message to be hidden. This paper intends to give an overview of image steganography, its uses and techniques. It also attempts to identify the requirements of a good steganographic algorithm and briefly reflects on which steganographic techniques are more suitable for which applications. I. Introduction The word steganography comes from the Greek Steganos, which mean covered or secret and Graphy mean writing or drawing. One of the oldest examples of steganography dates back to around 440 BC in Greek History. Herodotus, a Greek historian from the 5th Century BC, revealed some examples of its use in his work entitled " The Histories of Herodotus ". One elaborate example suggests that Histaeus, ruler of Miletus, tattooed a secret message on the shaven head of one of his most trusted slaves. After the hair had grown back, the slave was sent to Aristagorus where his hair was shaved and the message that commanded a revolt against the Persians was revealed [14]. In this example, the slave was used as the carrier for the secret message, and anyone who saw the slave as they were sent to Aristagorus would have been completely unaware that they were carrying a message. As a result of this, the message reached the recipient with no suspicion of covert communication ever being raised. The main goal of steganography is to communicate securely in a completely undetectable manner and to avoid drawing suspicion to the transmission of a hidden data [4]. It is not to keep others from knowing the hidden information, but in contrast to cryptography, it is to keep others from thinking that the information even exists. The basic model for steganography is shown on fig. 1. The model shows the basic process involved in steganography which consists of Carrier, Message …