# Building Cryptosystems

Daniel J. Sturtevant
Engineering Systems Division
Massachusetts Institute of Technology
Cambridge, Massachusetts 02139 USA

This video module presents an introduction to cryptography – the method of sending messages in such a way that only the intended recipients can understand them. In this very interactive lesson, students will build three different devices for cryptography and will learn how to encrypt and decrytp messages. There are no prerequisites for this lesson, and it has intentionally been designed in a way that can be adapted to many audiences. It is fully appropriate in a high school level math or computer science class where the teacher can use it to motivate probability/statistics or programming exercises. The video module itself should take one class session, although the building of the cryptography devices may take longer and could be done ahead of time. Materials necessary for this lesson include paper cups, scissors, tape or glue and pens or pencils. Additional materials are downloadable from this website. During the in-class portion of this interactive lesson, students will learn to build the cryptography devices and will learn how to send and “crack” secret messages.

Dan Sturtevant is a Ph.D. student with prior degrees in engineering, political science, and management. He is a software engineer with industry experience in Linux, cryptosystems, and simulation modeling. He is interested in how computers can help us improve our lives and better understand ourselves.

This page is from the website of Thomas Jefferson's home, Monticello, and discusses the history and mechanics of Jefferson's Wheel Cipher.
http://www.monticello.org/reports/interests/wheel_cipher.html

http://www.monticello.org/jefferson/wheelcipher/index2.html

This article provides a comprehensive history of the British cryptoanalysts who broke the Enigma Machine code during World War II.
http://www.pc-wholesale.com/computer-code-cracking-and-cryptology.html

This site provides extensive information on the Enigma Machine, including history, classroom exercises and additional resources on the topic.
http://plus.maths.org/issue34/features/ellis/

Information on cryptography from the Internet Mathematics Library of the  Math Forum@Drexel University.
http://mathforum.org/library/topics/cryptography/

A more advanced and comprehensive introduction to cryptography
http://www.ciphersbyritter.com/LEARNING.HTM

http://www.secretcodebreaker.com/videos.html

This website, sponsored by the company, Barcodes, Inc., provides articles on a wide variety of topics related to cryptography.
http://www.barcodesinc.com/articles/cryptography2.htm

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