WWII Encryption Test

At the end of my WWII unit, students had gained an appreciation for the value of breaking the enemy’s codes — the British against the Germans, and the Americans against the Japanese.

In that spirit, three or four days before the breathtakingly hard assessment for the Great Depression and World War II I announce with much fanfare that I posted the multiple choice unit test in a public place. The test is encrypted, I tell them, and if they can break the code they can have that test (and then the answers, presumably). I announce the test is encrypted with a 4096-bit PGP key. I urge them to read about codes and encryption. I tell them to talk to the calculus teacher, or anyone who has very strong math skills. Do they have an uncle that works for the NSA?

A day or two later they come back in protest. It is impossible to brute force attack such a large number, hoping for a random match.  I ask them to pool their computer-crunching power. But I make sure to only give them a couple of days to attack the code.

A perfect tweak to that unit that intrigues advanced students — the challenge of achieving the impossible!

Or is it “possible”?

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