Illustration of Watermarking (Lossy Vigenere)

Simon Singh demonstrated a lossless Vigenere in his book, “The Code Book.” I learned it differently in my youth, under the moniker “Rogue’s Gallery.”

This (symmetric) Vigenere is “lossy,” and replaces lost information with the character “z.” The placement of the “z’s” is password dependent, so encrypting and decrypting with one password, and then performing the same operation with a different password, illustrates the principle of a password dependent watermark.

screen_watermark

(Python Implementation)

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About James Johnson

I am an amateur mathematician & political theorist who enjoys (occasionally cerebral) humor.
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