Classical ciphers are typically applied to English text, but they can also be used to encrypt images and sound files to add an audio-visual component to cryptology courses that is appealing to both mathematical and general audiences. Using audio-visual plaintext has the added benefit of more clearly revealing the strengths and weaknesses of classical ciphers since images and sounds are much more error-tolerant than text. Finally, we introduce ECrypt, a free program that makes it easy for everyone to encrypt image and sound files.

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