WWII Cryptology: The Fatal Flaw of Repeated Messages
2025-08-31
A declassified US Army cryptology manual reveals a crucial strategy in WWII US military communications: never send the same message twice, even using different encryption methods. The manual details the importance of 'paraphrasing'—rewriting messages to change wording without altering meaning—to avoid repetition. This echoes the Allied experience breaking German Enigma codes, where the repetition of messages encrypted with different methods provided crucial clues. This underscores that in cryptography, operational procedures and protocols are as vital as the encryption technology itself.
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cryptology