04 Jun 2008 14:58
As England's historic Bletchley Park raises funds to restore buildings used by code-breaking legends such as Alan Turing during World War II, CNET is taking a look back at the cryptographic machines that kept vital specialists of the German, American, British, Polish and Japanese military forces awake at night.
Of course, the technology used by the most ambitious machines of their day, which were used to protect and decipher secret messages regarding defence and diplomacy, stems from something much older: the most basic cipher machine, invented in 1467 by Leon Battista Alberti of Italy. (A true Renaissance man, Alberti's accomplishments also spanned art, architecture, poetry and philosophy.)
By aligning the plain-text letters in one row of a cipher disk, any other row can be selected as the cipher text. If someone, for example, aligned the A on the outer ring with the G on the inner ring, this would make the following substitution alphabet used to encrypt a message:
OUTER RING: ABCDEFGHIJKLMNOPQRSTUVWXYZ
INNER RING: GHIJKLMNOPQRSTUVWXYZABCDEF
From there, a message coder could encrypt his message and send it to someone who knows the co-ordinates to decode the message, arranging identical wheels in the same order and aligning the cipher letters in a row.
Found by a West Virginian antique dealer in a home near Thomas Jefferson's Monticello estate in Virginia, according to the US National Security Agency, this particular artifact — built for use with French, the standard diplomatic language at the time — is thought to be the world's oldest existing cipher device. It uses scrambled alphabets on the edges of each wheel to cipher a message, and its individually numbered wheels can be placed on the spindle in any prearranged order.
Credit: National Security Agency
This Enigma cipher machine, captured by the US Army in World War II, was used by the Germans to encrypt messages that may land in enemy hands. The Enigma family of electromechanical rotor machines — first used commercially in the early 1920s, according to Bletchley Park researchers — used wired rotors and plugs to change each letter as it was pressed on the keyboard.
Every day, the order of the wired rotors inside the Enigma machine was switched according to a keylist — thus making it difficult for an enemy to figure out its complicated pattern. Until the creation of the Navy Bombe, the Enigma's secret messages were unbreakable without a keylist.
In fact, one version of the Enigma was considered by Germany to be completely unbreakable, as it could be set up in any one of a vast number of ways (two times 10 to the 145th power), each of which would encrypt a plain-text message differently. More than 60 years after the war ended, a distributed-computing project succeeded in deciphering a message encoded with the four-rotor machine.
After many years of trying, Polish mathematicians during World War II discovered how the mathematical calculations of the Enigma were created. Because the machine's key was changed every day, however, decoding Germany's secret messages by hand was too slow. They created the Bombe to test the Enigma's 17,576 settings, according to the National Security Agency.
At the beginning of World War II, British cryptanalysts at Bletchley Park, which now houses the National Museum of Computing, used Polish techniques and exploited weaknesses in German operating procedures to read Enigma messages.
According to the book Codebreakers: The Inside Story of Bletchley Park, Winston Churchill once described Bletchley Park as Britain's secret weapon that won the war. Bletchley Park is currently trying to secure funding to keep its doors open and save its numerous exhibits from rotting away, including several buildings used by the World War II code breakers.
Pictured here is a mockup of a Bombe machine at Bletchley Park.
Credit: Sarah Hartwell
The Bletchley Park Trust says it needs about a million pounds to repair the roof of the park's mansion and a similar amount to restore three huts used by legendary figures such as Alan Turing.
At the bottom of this commemorative British envelope are images of three men who helped crack German codes. Alan Turing (right) had built a machine, called Bombe, that could crack the codes of Enigma. Bombe was electromechanical, and therefore the speed at which it could calculate was limited. Turing recruited Tommy Flowers (left), who proposed making a completely electronic machine to crack the codes. Flowers was assisted by Allen Combs (centre).
Turing, an antiwar protestor in the 1930s, eventually moved on to design the Automatic Computing Engine (ACE) in 1945. Flowers went back to designing and building Post Office telephone exchange systems.
Credit: Bletchley Park Post Office
As the war continued, the Germans created better versions of the Enigma that were even harder to decipher. According to the US National Security Agency, that's when the US Navy stepped in, working with the National Cash Register to build 120 Cryptanalytic Bombes in Dayton, Ohio, aimed at breaking the Germans' secret messages.
Credit: National Security Agency
The Germans had cipher devices even more sophisticated than the Enigma. The Lorenz SZ40/42, given the code name Tunny (slang for 'tuna'), was one such high-grade cryptomachine. It used the international telegraphic 'Baudot' cipher and an additive placed on the cipher by the rotors to stream high-level teleprinter messages, according to the NSA. Bletchley Park researchers focused on the Tunny, which was in full use by the Germans for high-level communications by 1941.
Credit: National Security Agency
The Sturgeon, another so-called 'fish' cipher, was primarily used by the German Air Force, according to the NSA. It was capable of high-speed teleprinter transmissions. This particular machine used cable rather than radio to transmit its messages, thus decreasing the allies' ability to intercept.
Swedish mathematician Arne Beurling was the first to decipher and reverse-engineer the Sturgeon (also known as the Geheimfernschreiber and as the Siemens and Halske T52), a feat he accomplished in just two weeks. He later became a Princeton University professor.
Credit: National Security Agency
In 1943, capitalising on human error in the use of Tunny, British cryptanalysts were able to crack the system — in theory, at least. "In practice, individual Tunny messages required too much processing time for use in military operations," the NSA said. So to cut down Tunny message decryption time from weeks to hours, British engineers and cryptanalysts built the first large-valve programmable computer, Colossus.
The programmable Colossus Mark 1 system, which used 1,500 vacuum tubes to calculate, helped crack the secret codes of the Third Reich and speed up the end of World War II. By June 1944, subsequent Colossus machines using 2,000 valves were cracking German high-command codes to pave the way for D-Day.
This is a picture of the Colossus Mark II, still residing at Bletchley Park, which a group of enthusiasts worked for nearly a decade to rebuild. The British government had dismantled it to prevent any Cold War enemy from discovering such advanced technology.
Credit: Colossus Rebuild Project
Today's version of the Colossus took 14 years to assemble, according to Anthony Sale, who headed the team that rebuilt the computer.
"All the drawings were burnt in 1960, so all we had to go on were six black-and-white photos and 10 fragments of circuit diagrams," Sale said. "The machine has 2,500 valves, so it was a challenge piecing it all together."
Credit: Bletchley Park Trust
The US Army's Sigaba — also known as the ECM, or Electric Cipher Machine, in the US Navy — was reputedly the only system used during World War II that remained completely unbroken by an enemy, according to the NSA. ("The Germans never broke it, and the Japanese gave up trying," according to the agency's special coverage of 'big machines'.)
Although the Sigaba utilised the German Enigma's principle of rotating, removable wired rotor wheels, its stepping motion was far more complicated, appearing random. "Ten of Sigaba's 20 rotors could be taken out and moved to a different position; the rotors could be placed in the machine either 'forward' or 'backward'; and any one or more of the rotors could move with each keystroke," according to the NSA.
Credit: National Security Agency
A Japanese family of high-level encryption machines using telephone selector switches came to be known in the US by their colourful code names: Coral, Jade and Purple. Their names derived from the colours of the binders US cryptanalysts used to enclose material about the respective systems.
The Japanese Imperial Navy used the Jade machine's Shift key and 25 letter keys to encrypt the 48 characters of the katakana syllabary. Although most were aboard ship, this Jade was captured on Saipan when US forces took the island in June 1944, according to the National Security Agency.
Credit: National Security Agency
The ultimate Japanese encryption machine for diplomatic messages, code-named Purple, included a plugboard. It was the successor to the faulty prototype Red machine, which used a half-rotor switch that needed to be cleaned every day, according to the NSA.
Twenty letters could be plugged and routed through three units of the Purple electromechanical stepping-switch device, while the other six letters went through only one unit.
Credit: National Security Agency
After 18 months of analysis, cryptanalysts from the Army's Signal Intelligence Service determined that telephone-switching units could be the basis for the Purple machine (pictured here is its cipher switch).
An analogue machine was used by the US Army to decipher a 14-part message telling the Japanese ambassador to break relations with the US on 7 December at 1pm.
The US Signal Intelligence Service, using the analogue, had decrypted the message by 5am. War was clearly imminent, according to the National Security Agency, but the message lacked details. Regardless, some believe that breaking Purple is the greatest feat in cryptologic history.
Credit: National Security Agency
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