Cryptology and Cybersecurity for Young Scholars ~ Part Three: Decipher This!

This is the third in a series of posts related to the study of CRYPTOLOGY for advanced students in grades 3-5. See also: Part One: The History of Codes and Ciphers and Part Two: Crack the Code! FIND A VIRTUAL SLIDE SHOW READY-TO-SHARE WITH STUDENTS HERE!

Making and breaking codes and ciphers can be fun challenges for kids of all ages, and in this portion of the mini-unit, my students always enjoyed deciphering their way through an interactive mystery of some kind. In this post, I’ll share how you might lead up to that experience and include explanations of modern computer encryption methods and the role of mathematics in cryptology, adding depth to the unit and enhancing students’ appreciation of the importance of this area of study.

INTRODUCTORY ACTIVITIES

Begin by asking students what they would do if they wanted to send a secret message and they could NOT use invisible ink. They might say that they’d replace the letters in the message with either symbols, numbers, other letters, or some kind of motions. Explain that, in that case, they’d be using a substitution cipher, one in which the individual letters of a message are substituted with something else. The PLAIN TEXT is enciphered or encrypted into CIPHERTEXT and hopefully, only the sender and receiver know the cipher and KEY that will unlock the message.

If students answer by saying they would jumble the letters or wrap their message around a scytale (as presented in Part One), they would be using a transposition cipher, a cipher in which the letters of a message have not been substituted but have been repositioned.

A cryptogram puzzle is a substitution cipher and a great way to incorporate a lesson on letter frequency in the English language. In solving this type of puzzle, students usually instinctively know to look for certain patterns of letters and other language clues. You might start by sharing a cryptogram puzzle, such as the one below, and ask students HOW they would begin using these kinds of questions: “Where would you start? What would you look for?”

This lesson, offered by Marilyn Burns, engages students in discovering the frequency of letters in English words and sentences, and I recommend doing a lesson like this with students before solving cryptograms. Then, you can share this video lesson which guides students through solving the cryptogram shown above. Here is a student worksheet to accompany the video. I like to show just enough to get students started on the puzzle, give them some time to work on it, and then show a little more when they get stuck.

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DECIPHER THIS! ~ A DIGITAL ESCAPE ROOM

Because students may have prior knowledge of codes and ciphers, it’s sometimes better to assume they already know quite a bit (see “Six Strategies for Challenging Gifted Learners“). So, for the interactive mystery, various ciphers are presented in the form of some kind of a mystery to solve or “cyber challenge.” Given the current situation, with many students learning from home, I decided to create a digital escape room. Students take on the roles of “cybersecurity trainees” who must decipher encrypted messages in order to pass a training test and become eligible for further training. A digital handbook is provided to help them through the process. Here is an ANSWER KEY (password-protected so that students cannot access ~ please subscribe in order to get the PASSWORD)

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ENCRYPTION ON THE INTERNET

Internet encryption is the product of complex mathematical algorithms, but students benefit from being introduced to RSA encryption, named for the three computer scientists who created it: Ronald Rivest, Adi Shamir, and Leonard Adleman (note the first letter of each man’s last name- R S A). The idea behind RSA and asymmetric encryption is that instead of having ONE KEY used by both the sender and receiver, there are TWO KEYS, one public and one private. Bank transactions, online shopping, and all kinds of internet interactions are enabled through the use of PUBLIC KEY CRYPTOGRAPHY.

The video below explains the basic concept behind RSA Encryption in an engaging way for students! If you have students highly gifted in math who want to learn more about the RSA algorithm, you can find more explanation here, and here is another video that explains asymmetric encryption.

Here are a few additional resources. Please comment below if you have favorite activities for students that relate to cryptography and cybersecurity. Watch for a future post about the “Internet of Things” and the cybersecurity issues surrounding our “smart” devices, appliances, and buildings.

ADDITIONAL RESOURCES

• Encryption for Kids
• Science Show: “Cryptography: The Science of Making and Breaking Codes” (video)
• Cracking Codes Lesson and Resources
• Crypto Corner – Downloadable Resources
• Puzzlemaker – students can make their own cryptograms
• Pigpen Cipher – Encrypt /decrypt a message