Ep.18: Secret Codes & Ciphers

Cryptography is the writing and decoding of secret messages, called ciphers. Now for governments these secret ciphers are a matter of national security. They hire special cryptanalysts who work on these ciphers using cryptanalysis. The secret is, solving substitution ciphers can be pretty entertaining! Ciphers are published daily in newspapers everywhere. If you practice encoding and decoding ciphers, you too can become a really great cryptanalyst.

Download the student worksheet that goes with this lesson.

The Date Shift cipher is a much harder code to break because the shift number varies from letter to letter, and also because it’s polyalphabetic (this means that a single number can represent multiple letters). I’ll explain it all here.

What do you think about the Date Shift cipher? The possibilities for numerical keys are endless. You can use the date you’re sending the message, birth dates, phone numbers, and more! Just remember to start decoding by writing the key numbers over the top of the encoded cipher. And always makes sure the decoder has the correct numerical key!

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