What is Steganography?

Steganography deals with composing hidden messages so that only the sender and the receiver know that the message even exists. Since nobody except the sender and the receiver knows the existence of the message, it does not attract unwanted attention. Steganography was used even in ancient times and these ancient methods are called Physical Steganography. Some examples for these methods are messages hidden in messages body, messages written in secret inks, messages written on envelopes in areas covered by stamps, etc. Modern Steganography methods are called Digital Steganography. These modern methods include hiding messages within noisy images, embedding a message within random data, embedding pictures with the message within video files, etc. Implement steganography by How to hide text in image.

Types of Steganography:

Digital text

In Digital text one can perform steganography by making text the same color as the background in word processor documents, e-mails, and forum posts.Using Unicode characters that look like the standard ASCII character set. On most systems, there is no visual difference from ordinary text. Some systems may display the fonts differently, and the extra information would then be easily spotted, of course.Using hidden (control) characters, and redundant use of markup (e.g., empty bold, underline or italics) to embed information within HTML, which is visible by examining the document source. HTML pages can contain code for extra blank spaces and tabs at the end of lines, and colours, fonts and sizes, which are not visible when displayed.Using non-printing Unicode characters Zero-Width Joiner (ZWJ) and Zero-Width Non-Joiner (ZWNJ). These characters are used for joining and disjoining letters in Arabic and Persian, but can be used in Roman alphabets for hiding information because they have no meaning in Roman alphabets: because they are “zero-width” they are not displayed. ZWJ and ZWNJ can represent “1” and “0”.

Social steganography

In Social steganography is performed by Hiding a message in the title and context of a shared video or image or misspelling names or words that are popular in the media in a given week, to suggest an alternate meaning.

Network

Network steganography covers a broad spectrum of techniques, which include, Steganophony — the concealment of messages in Voice-over-IP conversations, e.g. the employment of delayed or corrupted packets that would normally be ignored by the receiver (this method is called LACK — Lost Audio Packets Steganography), or, alternatively, hiding information in unused header fields.WLAN Steganography – transmission of steganograms in Wireless Local Area Networks. A practical example of WLAN Steganography is the HICCUPS system (Hidden Communication System for Corrupted Networks)

Printed

Printed steganography is made by the digital way of printing the on the paper or it may be done by using the cipher text but it is not printable. For example, the letter size, spacing, typeface, or other characteristics of a cover-text can be manipulated to carry the hidden message. Only a recipient who knows the technique used can recover the message and then decrypt it. Francis Bacon developed Bacon’s cipher as such a technique.