Hidden in Plain Sight
Steganography is used by some modern printers, including HP and Xerox color laser printers. Barely visible tiny yellow dots on each page contain encoded printer serial numbers as well as date and time stamps. Many color printers produce these yellow dots to encode printing date, printer type and printer ID.Copyright 2008 Parhamr, Wikimedia Commons http://commons.wikimedia.org/wiki/File:Printer_Steganography_Illustration.png
Steganography is the science and art of hiding messages in plain sight so only the sender and intended recipient know the existence of a message. Steganography can be characterized as security through obscurity. Through this lesson, students experience a portion of the engineering design process as they research steganography and steganographic methods; identify problems, criteria and constraints; brainstorm possible solutions; and generate ideas. These are the critical first steps in the engineering design process, often overlooked by students who want to get to the "doing" phases—designing, building and testing. In computer science, a thorough design phase makes program implementation much easier and more effective. Students obtain practice with a portion of the design process that may be less exciting, but is just as important as the other steps in the process.
Along with its associated activity, the lesson is designed to provide students with practice in implementing the engineering design process. Students identify a problem, develop solutions, select and implement a possible solution, test the solution and redesign as needed to meet requirements. The process is driven by the concept of steganography, which may be new to students and potentially intriguing. For a centuries, individuals and governments have delivered messages to interested parties secretly using steganography. More recently, terrorists use steganography to hide messages from law enforcement. Software engineers, both those who hide messages and those who attempt to detect messages, use the design process to identify methods for hiding information and detecting the very subtle document and image changes that indicate the presence of hidden messages. These software engineers are on the front lines in detecting illegal behavior that is planned and communicated via steganography.
After this lesson, students should be able to:
- Research and explain steganography.
- Compare and contrast several different methods of steganography.
- Describe positive and negative uses of steganography.