Steganography is a technique of hiding information in digital media. Don’t be confused it with Cryptography. Basically, the purpose of cryptography and steganography is to provide secret communication. Cryptography modifies the content in an unreadable form (encryption), whereas Steganography is the practice of hiding private or sensitive information within something that appears to be nothing out to the usual.

Steganography isn’t something new, throughout history Steganography has been used to secretly communicate information between people.

Some examples of Steganography in past times are:

  • During World War 2 invisible ink was used to write information on pieces of paper so that the paper appeared to the average person as just being blank pieces of paper. Liquids such as milk, vinegar and fruit juices were used, because when each one of these substances is heated they darken and become visible to the human eye.
  • In Ancient Greece they used to select messengers and shave their head, they would then write a message on their head. Once the message had been written the hair was allowed to grow back. After the hair grew back the messenger was sent to deliver the message, the recipient would shave off the messengers hair to see the secret message.

In Modern times, Steganography is mainly used in Image, Audio and Video. Essentially the difference between cryptography and steganography is that, while both hide a message, steganography is meant to make the message invisible, while cryptography changes the message’s form, by means of replacement and/or algorithm.