Text Version of the Article
THE SECRET LANGUAGE OF WAR
BREAKING JAPANESE CODE BEFORE PEARL HARBOR WAS CLIMAX OF AN UNCEASING AND UNKNOWN BATTLE
by FRANCIS SILL WICKWARE
One of the most exotic melodramas of the century might be titled "The Great Code Mystery" or, How Much Did We Know about the Japs?" According to the celebrated letter which General Marshall sent to Governor Dewey during the 1944 presidential campaign, we somehow had broken the top Japanese diplomatic code some time before Pearl Harbor. It also seems clear that in some manner the U. S. Navy obtained the Jap navy codes (as distinguished from diplomatic codes) and throughout the war was informed about important Japanese moves and maneuvers.
Tantalizing rumors have been circulating. It is said, for example, that we obtained the Jap codes from a member of the Imperial Diet who actually was a secret U.S. agent. This individual, according to the fantasy, will be tried as a war criminal, sentenced to death and then spirited away beyond the reach of assassins. Another rumor is that possession of the codes not only determined the whole course of the Pacific war but had a very important bearing on the German war as well. The story goes that in the winter or early spring of 1944 the German High Command took some Japanese attachÃ©s from the Berlin Embassy on a tour of the fortifications along the invasion coast. Later the Jap attachÃ©s radioed a detailed account of the tour to Tokyo in the diplomatic code. This was intercepted by U.S. monitors and decoded message gave the invasion chiefs precise information on which points to hit on D-day.
Several months ago President Truman issued a directive prohibiting any official disclosures whatever about codes, without White House sanction. There is also pending in Congress a bill known as S-805 which provides a fine of $10,000 and/or ten years' imprisonment for anyone divulging code information or even information about messages "purporting to be in code." However, while the full truth about the Great Code Mystery may never be told, it is possible to say a good deal about codes without violating national security. The subject is an old one. It goes back at least to the Fifth Century B. C., when a Greek named Histiacus shaved the head of a slave, tattooed a secret message on his scalp, waited until the hair grew back and then sent him forth as a diplomatic courier.
Every major government maintains a "black chamber" ceaselessly decoding communications of other governments-friendly or not-in peace as in war. The headquarters of these recondite groups are as inaccessible as Mt. Everest. The code department of the U.S. State Department consists of 15 connecting rooms to which there is only one entrance through a grilled gate which is opened only for employees and a few top officials. Twenty-four hours a day code messages flow in and out over wires which lead into the central cable room and connect the department with its antennae all over the world. Certain messages are so top-secret that, after they have been read and noted, they are burned. There is a special incinerator for this purpose, and care is taken that only dead, powdered ash remains.
In the last war, vital cryptographic work was left to a comparative handful of advanced mathematicians, professors of dead languages and assorted savants, whose composite information had to equal that of a generously endowed library. The possibilities of cryptography are almost limitless. In the last war U.S. Indians from various tribes were employed in communications on the theory that if they spoke back and forth no one could understand them. They indeed proved so troublesome that after the war numerous German "students" and "professors" came to the U. S. to study Indian languages and are supposed to have compiled the best Indian dictionaries in existence. However, it appears that the Navajo dialect is so difficult that there are said to be only i8 non-Navajos in the world who know anything about it. A recent issue of the Marine Corps Gazette mentioned the use of Navajos in the Pacific campaigns. There are scores of obscure Chinese, Siberian and Asiatic-Indian dialects which might be adapted to cryptography, and the masterminds in charge of the black chambers must be able to spot them.
A special "war of nerves" constantly is fought between rival code rooms. One favorite trick is to flood all communications channels with scores of meaningless messages in different codes and ciphers in an effort to wear down the decoders on the other side. Then, when they are approaching the nervous-breakdown stage, a genuine message will be transmitted. Even with shifts of fresh clerks coming in every few hours, the strain and tension in the midst of a code barrage is almost unbearable.
Apart from familiarity with foreign languages and dialects, the code experts must have a broad knowledge of literature, which is important in unraveling so-called "codes." In using a book code two correspondents select a certain volume as a key and communicate by sending messages consisting of numerals referring to page and line in the book. Theoretically any book can be used, but for practical purposes a dictionary generally is chosen.
In popular legend the notion persists that a book code is unbreakable. Actually no one ever has invented an unbreakable system. Possibly the only exception is the famous 13th-Century manuscript attributed to Roger Bacon written in a cipher which has baffled cryptanalysts for decades. No cipher method of secret writing can get very far from the fact that in every language certain letters and letter combinations occur far more frequently than others. In English, for example, the letter E occurs 591 times in every 1,000 words on the average, T occurs 473 times, followed by A, 0, N, R, I, S, etc. Similarly, the bigrams TH, HE, AN, RE, ER and the trigrams THE, ING, ENT, ION, etc., are conspicuously frequent. No matter how complicated the cipher, it is impossible entirely to suppress these frequencies and usually they are the key to the puzzle.
Good guessing is important
But frequencies are no help in solving special, isolated messages such as the famous A SON IS BORN which informed Germany's diplomats that the first World War was about to begin. Only after the interception of a considerable volume of coded messages is it possible to discern the word patterns which inevitably emerge in time. Besides piecing together the code samples which slowly accumulate, decoders carefully consider the time and place of transmission of each message, its probable destination, the probable language of the original text and, most important of all, its possible correlation with subsequent political or military happenings. In this way a body of knowledge, observation and conjecture is built up and, finally, the most abstruse code is broken. By and large it is likely that ten or twelve months will be required to break a modern code, barring occasional lucky accidents or masterful espionage. Therefore the general practice is to change codes every five or six months, thus thwarting the enemy decoders.
Codes are the basis of all U.S. naval communications and there is no secret of armament, gun range or firepower more closely held than the heavy, leadbound Navy codebooks. On every warship three officers are privy to the whereabouts and use of these precious volumes, and these officers also have the responsibility of disposing of the books if their ship is sinking. Under no circumstances must the codes go down with the ship, for if it is sunk in shallow water the enemy could and would send divers down to recover them. It may be that our knowledge of the Jap navy codes was obtained by recovery of codebooks from sunken ships.
If so, there is a classic precedent. During World War I the German cruiser Magdeburg ran aground on shoals in the Baltic, and the Russian fleet closed in on her. The captain of the Magdeburg then ordered an officer to take the codebooks off the ship and throw them into deep water, but before he could do so the Russians opened fire and he was thrown overboard. When the Magdeburg was taken, the Russian commander courteously ordered the bodies of the drowned German sailors brought up for honorable burial. One of the first bodies raised by the dredge was that of the officer, still clutching the lead covers of the codebooks. The Russians then put a diver to work, and in a short time he came up with the books themselves. These were sent to Room 40 in the British Admiralty, and for two years, until after the Battle of Jutland when the Germans adopted a new system, the British Navy usually had full information about projected enemy raids and fleet maneuvers, with incalculable effect on the course of the war.
The U.S. Army uses code for messages of vital importance and for most communications referring to troop movements, munitions, supplies, etc. But it would be far too risky to have codebooks lying around in combat areas where they might be captured, so in the field the Army depends mostly on a system of ciphers nicely graduated in complexity. For example, an order calling for a certain action in three hours would be put into a relatively simple cipher which, if intercepted, could not be read by the enemy in less than five or six hours. An order for action a day later would be in a more difficult cipher which might take three days to solve, and so on. An order for immediate action would be sent in clear text by the quickest means available, regardless of whether the enemy intercepted it or not, because the attack presumably would be under way before the enemy could prepare to meet it. Likewise, communications between fighter planes and tank units in battle are in clear. But if Washington sent important instructions to General Eisenhower or General Mac Arthur, no chances were taken. The messages were coded and the code then enciphered, and it might have taken months for the Germans or Japs to make any sense out of them.
The Army could, of course, send all messages in its most difficult ciphers and keep switching them so often that the enemy would always be weeks behind in its deciphering efforts. But a cipher is a mechanism and, like every mechanism, it is subject to accidents. Some ciphers are so delicately constructed that an error in a single character is enough to change the meaning of an entire message-or turn it into gibberish. The rout of Napoleon's Grand Army at the Battle of Leipzig was caused in part by a garbled cipher message from the marshal of a relief army which was supposed to cover the retreat of Napoleon's forces from a dangerous position. The message, in Napoleon's "Great Cipher," informed the emperor that the army could not reach the appointed place at the appointed time. But a mistake had been made in the encipherment and no one at headquarters could read it. Napoleon lost the battle and a large part of his army.
The mechanical word shuffler
While the cryptographers are trying to read enemy messages and trying to devise indecipherable ciphers and unbreakable codes for our use, communications experts also are at work. Their job is to invent methods of transmission which will defy enemy interceptors. One of the most ingenious devices is a "four-channel time-division multiplex basis transmitter." In spite of the formidable name, this is similar in principle to an old dodge of secret writing long used by criminals. A prisoner, say, will write a message on the side of a tightly held pack of cards, arranged in a certain sequence. He then shuffles the cards and passes them on to another prisoner who reads the message by putting the cards back into the original sequence. The "four-channel" transmitter in effect is a mechanical shuffler of code words. A rotating switch is connected with four sending machines and thoroughly mixes all the syllables of the message being sent. The resulting jumble goes out on a single radio frequency, and at the receiving end there is another rotating switch hooked up to four automatic typewriters. The receiving apparatus is synchronized with the transmitter and breaks down the jumbled message into the four parts of the original.
There also are in use today certain secret refinements of the "lightning gibberish" which the Germans broadcast from their great radio station at Nauen in World War I. Lightning gibberish consists simply of recording a message, then playing the record at five or six times normal speed for radio transmission. The result is a high-pitched screech. For quite a long while the Allied interceptors were unable to make sense out of Nauen's screeching, until one day some British officers played some records of the Nauen broadcast on a portable phonograph. The phonograph ran down in the middle of the record, and the screech turned into an audible series of code groups.
Readers who may wish to experiment with the secret language of war can use the cipher below, the historic VigenÃ¨re tableau. Invented by one, Blaise de VigenÃ¨re, a Frenchman, the tableau for many decades was called the indecipherable cipher, because of the ingenious way that letter frequencies are hidden. The VigenÃ¨re long ago lost its reputation of being indecipherable, but it is the ancestor of most ciphers in use today.
To write a VigenÃ¨re cipher, sender and receiver must have a key word. Suppose the key word is CIPHER and the message is SECRET WRITING. The sender begins with CIPHER/CIPHERC; SECRET/WRITING, the key word being repeated as often as necessary to match each letter of the message.
In composing the cipher, the sender starts with the first letter of the key word, the C. He then reads down the vertical column under C in the top line until he comes to the horizontal line headed by S, the first letter of the message. The letter at the junction of these two lines is U, the first letter of the cipher. Likewise, under the I column he drops down to the E horizontal line and gets the cipher letter M, and so on. The completed cipher thus reads, Key word: CIPHER/C1PHERC; Message: SECRET/WRITING; Cipher: UMRYIK /YZXAMEI. Note that in the VigenÃ¨re cipher, the repeated letters in the message (E, I, R and T, in this case) are represented by different cipher letters each time.
To decipher, the receiver simply reverses the process. He goes down the column headed by the first letter of the key until he comes to the first letter of the cipher. The letter at the extreme left of that line thus is the first letter of the deciphered clear. Thus,-Key word:
CIPHER/CIPHERC; Cipher: UMRYIK/YZXAMEI; Message: SECRET/ WRITING.
Caption on page 63:
Bazerie's cylinder has 20 disks, each with a vertical alphabet scrambled differently. The disks are then revolved until desired phrase is spelled out on one horizontal line. Scrambled letters of any other horizontal line are sent as message. To decipher, this incomprehensible line is set up and the one intelligible line which appears among the 26 possible is the message.
Caption on page 64:
Soldiers learned cryptography for battlefront communications. They have been sternly warned not to talk about any Army codes. Above are shown U.S. troops in New Guinea.
Captions on page 66:
Secret "code-maker" is a slide-rule device which forms as many as 50,000,000 whole new codes based on letter or number substitutions. Placed as shown above, with the letter O equaling the letter R, A equals D, B equals E, and so forth. Or, in the reversel alphabet on the next line down, O equals I and A equals W, B equals V and so forth.
Army's M-94 uses perforated disks, the rims of which are imprinted with differently scrambled alphabets. Sender places numbered disks on spindle in any order, arranges letters on rims so one horizontal line forms a secret key sentence known to the receiv er (in this case, GRANT TOOK RICHMOND). Sender then informs receiver of order of the disks and tells him to turn each disk a certain number of letters, i.e., 5-9 means put disk on spindle first, then turn it 9 letters from the G in GRANT. Thus, disk by disk, new message-plain or in code-is spelled Out intelligibly on horizontal line.
Caption on page 68:
German spies learned cryptography in a Hamburg school which held classes in code- making. This picture is a scene from the movie about the FBI, The House on 92nd Street.
Here is a sampling of the table of contents from this issue.
Cover: Champion Afghan Dog, Paris GIs flock to Place Pigalle, Truman and Atlee meet in Washington, England's red dean visits US, Churchill's HQ, Rabbis march in Washington, The secret language of war by Francis Sill Wickware, The pilgrim myth, Ship graveyards, Folly Cove designers, Natalie Wood is new movie moppet, Dodgers sign negro Jackie Robinson, Bleeck's by Richard Manet, Nylon stockings revive classic leg art, Band formation documents history.