Zimmerman Telegram

In early 1917, during the early stages of World War I, British cryptographers encountered a German encoded telegram. This telegram is often referred to as the Zimmerman Telegram. These cryptographers were able to decipher the telegram, and in doing so they changed cryptanalysis history. Using this deciphered message, they were able to convince the United States to join the war.

The Zimmerman Telegram was a secret communication between the Foreign Secretary of the German Empire, Arthur Zimmerman, and the German ambassador in Mexico, Heinrich von Eckardt. The telegram contained an offer for Mexico to reclaim its territory of New Mexico, Texas, and Arizona if it joined the German cause.

Choctaw Codetalkers

As WWI went on, the United States had the continuing problem of the lack of secure communication. Almost every phone call made was intercepted by the Germans, leaving every move made by the allies known to the Germans. Army commander, Captain Lewis devised a plan that utilized American Indian languages. He found eight Choctaw men in the battalion and used them to talk to each other over radio and phone lines. Their language was valuable because ordinary codes and ciphers of a shared language can be broken, whereas codes based on a unique language must be studied extensively before beginning to decode them. Within 24 hours of using the Choctaw language as encryption, the advantage fell in favor of the United States. Within 72 hours, the Germans were retreating and the allies were in full attack.

Enigma Encryption Machine

At the end of World War I, Arthur Scherbius invented the Enigma, an electro-mechanical machine that was used for encryption and decryption of secret messages. Because of the numerous configurations, the Enigma was virtually unbreakable with brute force methods.

It wasn't until World War II that the Enigma gained its fame. Due to the Enigma's statistical security, Nazi Germany became overconfident about their ability to encrypt secret messages. This overconfidence caused the downfall of the Enigma. Along with numerous German operator errors, the Enigma had several built-in weaknesses that Allied cryptographers exploited. The major weakness was that its substitution algorithm did not allow any letter to be mapped to itself. This allowed the Allied cryptographers to decrypt a vast number of ciphered messages sent by Nazi Germans.

Purple

While the Allied forces were focusing on cracking the German Enigma, the Japanese developed an encryption machine called Purple. In contrast to the Enigma's rotors, Purple was made using stepping switches commonly used for routing telephone signals. During the war, the Japanese were most efficient in destroying their encryption machines. Currently, not one complete Purple machine has been discovered.

Because the Japanese were so good at keeping their encryption methods secret, the United States cryptographers had a hard time decrypting their messages. William Friedman, a renowned cryptographer, and his team built a replica of Purple based only on the encrypted messages recovered. Because they had never seen a Purple machine and didn't know how it worked, this proved to be very difficult. Eventually the team figured out the encryption method used by Purple, and were able to build a different machine for the decryption of it. This advancement allowed the United States to access the Japanese diplomatic secrets in World War II.

Notes:

Khnumhotep – древнеегипетский высокопоставленный придворный вельможа.

B.C. (Before Christ) – до нашей эры.

Scytale – шифр Древней Спарты, прибор для перестано­вочного шифрования.

Choctaw – коренной народ США, проживавший изна­чально на юго-востоке.