By Annie Laura Smith
Above, left to right: PFC Preston Toledo of Albuquerque, New Mexico and his cousin PFC Frank Toledo of Penistaja, New Mexico, at Ballarat, Australia with the 11th Marines in July 1943. Photo courtesy of the Photograph Collection at the Marine Corps Archives and Special Collections (COLL/3948).
Imagine sending a secure message that can be read only by the person for whom it was written. This is the intriguing world of codes and ciphers where letters of the alphabet are not what they seem to be. This kind of secret writing is known as cryptography.
Historically, governments have used codes and ciphers to protect information. Methods of sending secret messages with this ancient art form range from Greek skytales in the 5th century B.C. to the German Enigma in World War II. Today hidden messages embedded in pictures and music can be placed on the Internet through a process known as steganography.
Above, The Imitation Game portrays the life and work of Alan Turing, the man who helped the British beat Germany’s Enigma machine and secret code during World War II. Click here for more information.
During the 5th century, messages written on strips of parchment wrapped on Greek skytales (wooden cylinders) could only be read when wrapped on another cylinder of identical size. The German Enigma machine used during World War II had an electric keyboard. The typed-in message was changed letter by letter by a series of electrically wired codewheels known as rotors.
Some of our major victories in wars were a direct result of breaking the enemy’s codes, or preventing them from breaking ours. The British government set up a code breaking facility at Bletchley Park northwest of London during World War II. Their cryptologists broke codes on messages from the German Enigma, hastening the end of the war.
When the Navajo Code Talkers used their language as a code in the Pacific during World War II, this code was never broken by the Japanese. This unwritten language of the Navajos was based on their oral traditions of nature. For example, a transport plane was referred to as an Astah (eagle) because it resembled an eagle soaring through the sky carrying food. Other military language was similarly based on nature.
For example, imagine that you are a Navajo Code Talker, and develop a code based on nature. Write a coded message with the code using nature words in English.
If the Navajo Code Talkers needed to send a message to intercept a convoy, their nature language would include:
The Navajos would have changed the English words in nature to their language: TA-AKWAI-I TKAL – KAH-O-NEL, LO-TSO, BESH-LO, CHA, CA-LO.
The coded message in English would read: HALT MOVING ON WATER WHALE, IRON FISH, BEAVER, SHARK
Decoded Message: Halt convoy of battleship, submarine, mine sweeper, and destroyer.
There are a number of simple ways in which a message can be encoded. The original message is known as plaintext. It can be changed into a coded message in two ways: by transposition of the letters or by substitution of the letters. The methods of transposition or substitution of letters are known as cryptosystems. Note that the letters in a coded message are usually expressed in groups of five characters. When translated, however, the words in the message do not necessarily have five characters.
One of the easiest methods is the transposition of letters. For example, if consecutive letters are reversed (encrypted), the plaintext message DECODE THIS becomes the ciphertext or ciphergram by placing the E before the D (ED), the O before the C (OC) the E before the D (ED) the H before the T(HT), and the S before the I (SI). The coded message now reads: EDOCE DHTSI.
More complex codes using a series of mathematical transformations, algorithms, can be generated on a computer.
Other ‘secret writing’ involves a process different from transposition or substitution of letters. Steganography is the practice of embedding secret messages in other messages, pictures, or music in software such as on the Internet. These insertions are too small to be seen without retrieval with special software tools, and are thus difficult to detect.
Why do we need codes and ciphers in peacetime as well as in wartime? Codes and ciphers are used to send diplomatic information, protect business (banks, TV cable companies, phone companies, and other industries), and secure law enforcement information. The use of codes and ciphers will help our country to have safe communications in the future and keep America secure.