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Why was Georges J. Painvin’s solution of the ADFGVX cipher important during World War I?

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A Vigenere cipher table displays the alphabet in both the top row and left column, with rows shifted to create a grid for encryption and decryption. Highlighted letters illustrate how to use the table. An explanation and example using the words cipher, key, and plaintext appears to the right. — cryptology In encrypting plaintext, the cipher letter is found at the intersection of the column headed by the plaintext letter and the row indexed by the key letter. To decrypt ciphertext, the plaintext letter is found at the head of the column determined by the intersection of the diagonal containing the cipher letter and the row containing the key letter.

The ADFGVX cipher was a sophisticated fractionation system used by the German army during World War I to secure tactical communications. Its importance lies in the fact that it was one of the most advanced field ciphers of its time, combining substitution and transposition to create a highly secure product cipher.123

The French cryptanalyst Georges J. Painvin achieved a critical breakthrough in 1918 by successfully cryptanalyzing these ciphers. His ability to break this complex system had a devastating effect on German military operations, most notably during the Second Battle of the Marne and the battle for Paris. By providing the Allies with actionable intelligence, Painvin’s work significantly undermined German tactical planning at a pivotal stage of the war.12