RSA Cryptography
See “Public Key Cryptography and the RSA System” handout in the notebook.
RSA Activity:
Break the class into two groups and have each group encode (using the RSA system with p,
q, d, and e as selected in the handout) one of the following messages:
1. your prize is located in the main office
2. look on top of the lockers for your reward
Then have the groups switch encoded messages in order to decode the message encrypted by
the other group. After deciphering the encoded messages, the groups should follow the
instructions. For prizes we used cakes. The first group had a cake with “WYOO” on it, and
the other had “ATG!”. When the groups found their cakes, they were instructed to bring it
back to the classroom and to decode the message on the cake. They were not allowed to eat it
until the message was decoded. No hints were given as to how the messages on the cakes
should be decoded. However, decoding the message required stacking the first message on
top of the second and reading down the columns to spell “Way to go!” (see below).
Solutions for encoding/decoding the messages should be written out by the instructor in
order to check the work performed by the groups when encoding & decoding the messages
so that the messages are sent successfully.
WYOO
ATG!
Copyright 2007. Number Theory and Cryptology for Middle Level Teachers. Developed by the Math in the Middle Institute Partnership,
University of Nebraska, Lincoln.
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