Secret Writing by W. Scott Schindler 1920
Interest in secret writing - that strange science of cipher and code messages-was aroused during the Great War. "How," one often wondered, "did enemy spies in America get their reports safely to their home office?" The Allies controlled all overseas mails and cables and yet enemy agents in America seemed to have little trouble in communicating with Headquarters in the Fatherland.
Various systems of ciphers were used by means of which were sent, via neutral countries, innocent looking messages that appeared to say one thing, but that in reality said something very different.
IT IS interesting to compare the systems of secret communication used by modern nations in time of war with the methods of the past.
The art of secret writing dates back to Bible times. We find an account in Jeremiah (XXV-26), where the Prophet, to conceal the meaning of his prediction from all but the initiated, writes "Sheshak" instead of "Babylon"-the place meant-simply a pre-arranged change of certain letters in the Hebrew alphabet.
The Spartan rulers, on sending a general forth on an expedition, would provide him with a round stick of wood of a certain length and thickness, of which they would keep an exact duplicate. When they wanted to send him instructions they would take a long, narrow strip of parchment, roll it around the stick and write the message on it. They would then send the parchment to him, but without the wood. The strips of parchment alone could not be read, all the characters being broken up. "But," as described in Plutach's Lives, "taking his own staff he winds the strip on it, restoring all parts in the same order and so it can be read."
THE earliest known teacher of the science of "Cryptography" (from the Greek, kryptos-hidden), was the Abbot of Spangheim, who in the year 1516, wrote a book that became the basis on which future students workt. We find many of the private letters and papers of King Charles I and his Queen, both of whom were adept cipherers, in complicated numerals that long defied unraveling. They were finally deciphered by a Professor Wheatstone in 1858. Another Royal Cryptographer was Charlemagne, who used a curious cipher in parts of his correspondence.
John Haswell (Century Magazine, Nov., 1912), tells the story of Silas Deane, who was sent to France by the American Continental Congress to purchase arms and ammunition. To this very delicate duty was added the mission of sounding the French authorities as to their position toward the American Colonies "should the Colonies be forced to form themselves into an independent State." Deane needed no pretext to explain his presence in Paris. He posed as one of the many pleasure-seeking visitors to that famous city. But how could he correspond safely with his co-patriots at home? We
are told he adopted the simple trick of writing ordinary personal letters and then telling the real news in postscripts written in invisible ink. The recipient of the letter by applying heat to the paper would reveal the hidden message. Silas' scheme apparently workt-but this was 150 years ago. Today the trick of using invisible ink is known to every school-boy.
BY 1861 cipher and code messages were in common use, having been developt along with the commercial cables as a legitimate means of economy and secrecy in the import and export business.
Northern victories in several battles of the Civil War were due largely to the superiority of the Union Signal Corps in deciphering the Conferedate signals. Instances were also numerous in which the Confederates succeeded in intercepting Union messages by tapping telegraph wires; but usually these successes were followed by failure to decipher the captured messages.
Systems of secret writing are based either on a cipher or a code. Both ciphers and codes are substitutions-the distinction being in the unit chosen as the basis of the substitution. Cipher is based on a substitution of symbols for letters. Code is based on the substitution of words or symbols for words.
Example of a cipher:
A, B, C, D, E, F, G, etc., would be represented by:
! ? % : = ( $
But any message in so simple a cipher could easily be read by any expert into whose hands the message should be given.
In all languages there is a normal relative frequency of occurrence of the various letters of the alphabet. A rough key to any cipher that merely substitutes signs for letters may be had by examination of the relative quantities of letters in a printer's case. It will be found that in the English language the most frequently used letter is E, then T, then 0. Expert decipherers have figured the normal relative frequency of occurrence of letters in the English alphabet as:
Knowing this table, a decipherer groups and counts the unknown symbols of the message and substitutes the most likely letters. He is further assisted by the fact that letters used alone are A and I, while double letters are likely to be ee, oo, ff, ll, ss or tt.
A MOST fascinating story based on an enciphered message is Poe's The Gold Bug. In this tale the hero finds himself possest of a message written by Captain Kidd. The message appears to contain nothing but a series of meaningless signs and symbols. By using a "frequency of occurrence of letters" system the symbols are translated into words and the translator is rewarded by being directed to a fortune of buried treasure.
Poe appears to have been a deep student of every phase of the art of deciphering secret writing. The July, 1841, issue of Graham's Magazine contains Poe's Challenge to the Public, in which he claimed to be able to decipher any cryptogram that would be sent to him. He did not limit the ciphers to the English language; but invited problems in French, Italian, Spanish, German, Latin, Greek, or any of the dialects of those languages. It is said that of the hundreds of ciphers received, Poe solved them all but one, which proved later to be an imposition, a bunch of scrambled characters with no meaning whatever.
Altho it is admitted that almost any cipher message can be translated in time, still ciphers were much used in the Great War for messages where only temporary secrecy was desired. A cipher mesage sent by telegraph, telephone, wig-wag, semaphore or any other military method that ordered a regiment to advance in one hour would be safe, for even if intercepted by the enemy it would take them more than an hour to decipher it, and after an hour, the information would be valueless.
CODES are harder to translate by the outsider than ciphers; but codes are sometimes impractical as the correspondent must carry a code book or similar equipment. Codes have an additional value in that if cleverly used, they atract no suspicion when transmitted by telegraph or cable, or by means of a letter.
There would be nothing suspicious in the following cablegram from a New York stock broker to a banker in Holland: "Market price is 107." But suppose the broker and the banker were agents of an enemy country and their code books showed:
Munition ship = offered
Troop ship = market
Sailed from Norfolk = price
Sailed from New York = quotation
Sailed from Boston = closing
Today = is
Yesterday = was
For Liverpool = even number
For Bordeaux = odd number
For Neutral Port = number with fraction
Before the war, much international business was done by means of coded cables which allowed long messages to be sent by using a few words taken from a commercial code book. During the war, the Government required all messages to be in plain English; but many an innocent looking message got by and carried valuable information to the enemy. Also many an enemy spy found himself clapt into an American prison because his coded message to his Fatherland wasn't covered up quite cleverly enough to pass our American Secret Service, Post Office Department, Department of Justice and Military and Navy Intelligence Bureaus. All of these agencies workt in harmonious co-operation and captured many enemy plotters.
THE cipher and code systems used in the war were many and varied. In one instance an obscure edition of a dictionary was used as a code book. Messages sent by means of this code were combinations of three figures: figure 1 referred to the page in the dictionary, figure 2 to the column on the page and figure 3 was the number of the word in that column. 119-2-11 meant page 119, column 2, word 11. This system could be further complicated by finding the desired words in some book other than the dictionary. While not so satisfactory or so speedy, such a system would be almost completely safe. A simple system is made by forming the alphabet into a block as follows:
(NOTE: In the first block the letter "J" is omitted, and in the second block two XX are added in order that the blocks may be completely filled.) In using the first block, the writer would use the figure 22 to represent the letter "G." In the second block he would use the figure 71 to represent the letter "G."
This system is too simple to offer any resistance to an expert decipherer; but can be complicated by making false divisions between words, using dummy words, spelling every second or third word backward, etc., etc., as the imagination of the correspondents may dictate.
About the cleverest of the simple cipher systems is that called the Playfair and used by the British Army. A description of it, found in the June, 1918, issue of World's Work, says:
"First a square is drawn and divided into fifths each way. This gives twenty-five spaces to contain the letters of the alphabet (J and I in the same square). Next a "key word" is chosen-and herein lies the cleverness and simplicity of the Cipher, for every time you change the "key word" the pattern of the alphabet is changed. Suppose
"Gardenia" is chosen as the "key word:"
(The second A has been left out, as there must be no duplication). Assuming that we want to send the message, "Destroy bridge at once." We first divide up the letters of the message into groups of two as follows:
DE ST RO YB RI DG EA TO NC EX
(The X is added to complete the group and is called a "null".) Where two joined letters of the message appear in the same horizontal row on the keyboard, the next letter to the right is substituted for each. Thus, the first two letters of our message are DE. They occur in the same horizontal row on the keyboard and the next letter to the right is substituted for each. Thus,
quently for D we write E and for E we go "on around the world" to the right (or back to the other end of the row) and write G for E. This gives us DE enciphered as GE.
Where two joined letters of the original message appear in the same vertical row on the keyboard, the next letter below is substituted for each.
Where two joined letters of the original message appear neither in the same horizontal nor the same vertical row on the keyboard, we imagine a rectangle with the two letters at the opposite corners, and in each case we substitute the letter found on the keyboard at the other corner of the same horizontal row.
This sounds complicated, but it will be found to be quite simple. For example, take the third two letter group of our message-RO. The rectangle in this
case is:
R D E
B C F
L M O
For R we substitute E, for 0 we substitute L.
Substituting our whole message by this system, it reads:
Original: DE ST RO YB RI DG EA TO NC EX.
Cipher: EG TU EL XC AB EA GR UM IF RZ.
As telegraph operators are accustomed to send these gibberish messages in groups of five letters (so that they can check errors), these enciphered groups of two are now combined in groups of five so that the finisht cipher reads:
EGTUE LXCAB EAGRU MIFRZ
The foregoing sounds extremely complicated; but the truth is that anybody after half an hour's practice can put a message into this kind of cipher almost as fast as he can print the straight English of it and unless the person who reads it knows the key word which determined the pattern of his keyboard, he would have to be an expert to decipher it; and even an expert could do it only after a great deal of work.
The United States Government as such has no cipher or code system. Each Department,-State, War and Navy has its own system-which, for the sake of safety is changed from time to time.
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