Skill Level Intermediate
- [Narrator] Steganography is a term that describes concealing information within other information. It can be used to share messages, or transmit data without raising the suspicion of people who observe the information. A classic example of steganography, comes from videos of prisoners blinking their eyes in Morse code. Or in photos of them with carefully made holes in their clothing, to communicate a word or message in Morse code. Other common examples of steganography, involve highlighting or marking text in the document, that might not easily be noticed, or in making deliberate mistakes in text, the pattern or content of which communicates information, but which themselves look like careless typos, or common misspellings. Here we have a few short examples. One reading, "Happy Birthday", and another saying to meet on Tuesday. Information can also be communicated within a clear piece of text, if both the sender and receiver know of a particular pattern. Like to look for the second letter of every word, or the first letter of each sentence, or something like that. Here a note to a friend spells out Tuesday, if you read the first letter of each sentence. The longer the message, the more information can be communicated. Messages like this don't have to be made in long form documents though. They could be communicated in a shopping list, an order form, or anywhere else where there's enough text to get the message across, and the sender and recipient both know the pattern to look for. Other media can be used to communicate information steganographically as well. Like in the Morse code example, specific patterns can be agreed upon by people who want to communicate, and then that pattern can be represented in many different ways. An example of this would be turning off or removing specific bulbs from a string of decorative lights. Information can be encoded in many ways, and steganography also applies to many digital methods as well. Someone could use the time between key presses on a keyboard, to represent information, for example. And other technical methods can transmit even more information. These include modifying the actual information that makes up files to contain hidden information, without making the change obvious to someone who opens the original file. Some image and audio formats, have fairly high error tolerance, and where these errors in the file can be, a clever message sender could insert bits of other information, even other images or whole files. There are many other examples of steganography out there, and if you're interested, I encourage you to explore more. When you're exploring the corners of information security, you'll come across many interesting concepts and techniques. Messages and information sent using steganographic techniques, can be easy to use but hard to detect, if someone doesn't know what they're looking for.