STEG - Hiding and Revealing a Text Message (Lesson)

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Hiding and Revealing a Text Message

Introduction

Information can be represented in various ways, as seen through this lab with images being stored as 2D arrays of pixels. All information stored on a computer is stored as sequences of bits, and how those bits are interpreted can completely change their meaning. Consider the following eight-bit sequence – 0100 1101. It’s impossible to know what it represents without context. It could be the integer 77, the character ‘N’, the amount of red in a pixel, or any number of things.

The biggest consideration when determining how to represent information is knowing how many items need to be represented, since this will ultimately determine the number of bits that will be used. For example, early monitors were not capable of displaying the variance of color that current monitors can display, so colors were represented using far fewer bits. As monitors have improved and become capable of displaying more colors, the number of bits used to store color has increased so that all possible colors that can be displaced have a unique representation.

Click below to begin the Hiding and Revealing a Text Message Lab.

 

Check Your Understanding

Record the answers to the following questions on a sheet of paper. You will need the answers to complete the Lab Check Quiz.

 

  • 5. Given the representation scheme used, would it be possible to represent both uppercase and lowercase letters? What about digits? Exactly how many characters can be represented using the six-bit encoding scheme?
  • 6. When storing the secret message, a special value was used to signify the end of the message. Consider what would happen if there was no way to signal the end of a message. Which methods would change? Describe how the behavior would be different.

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