UNCLE SAM, DETECTIVE
THE detective work accomplished by the United States Government since its entry into the war has been worthy of a Sherlock Holmes, and yet few persons, reading only the results of this remarkably developed system, have realized that a Government heretofore finding it unnecessary to match wits with foreign spy bureaus has suddenly taken a high rank in this unpleasant but absolutely essential branch of war-making—as it has in all others. The public read of the intercepted dispatches from the Argentine to Germany by way of Sweden, and of the Bernstorff messages, but without a realization of the problem that a cipher dispatch presents to one who has not the key. And probably the average reader is unaware that, in both the army and navy, experts have been trained to decipher code messages, with the result that both the making and the reading of such dispatches have been reduced to an almost mathematical science. The Philadelphia Press, in outlining the instruction given in this important work at the Army Service schools, says:
What is taught the military will furnish an idea of the task of the code experts in the State Department, and of the basis of the science that has unmasked the German plans with respect to vessels to be spurlos versenkt and of legislators to be influenced through the power of German gold.
“It may as well be stated,” says Capt. Parker Hitt—that is, he was a captain of infantry when he said it—“that no practicable military cipher is mathematically indecipherable if intercepted; the most that can be expected is to delay for a longer or shorter time the deciphering of the message by the interceptor.”
The young officer is warned that one doesn’t have to rely in these times upon capturing messengers as they speed by horse from post to post. All radio messages may be picked up by every operator within the zone, and the interesting information is given that if one can run a fine wire within one hundred feet of a buzzer line or within thirty feet of a telegraph line, whatever tidings may be going over these mediums may be copied by induction.
In order that the student may not lose heart, it is pointed out in the beginning that many European powers use ciphers that vary from extreme simplicity to “a complexity which is more apparent than real.” And as to amateurs, who make up ciphers for some special purpose, it’s dollars to doughnuts that their messages will be read just as easily as though they had printed them in box-car letters.
At every headquarters of an army the intelligence department of the General Staff stands ready to play checkers with any formidable looking document that comes along in cipher, and there is mighty little matter in code that stands a ghost of a chance of getting by.
The scientific dissection of ciphers starts with the examination of the general system of language communication, which, with everybody excepting friend Chinaman, is an alphabet composed of letters that appear in conventional order.
It was early found by the keen-eyed gentlemen who analyzed ciphers that if one took ten thousand words of any language and counted the letters in them the number of times that any one letter would recur would be found practically identical with their recurrence in any other ten thousand words. From this discovery the experts made frequency tables, which show just how many times one may expect to find a letter e or any other letter in a given number of words or letters. These tables were made for ten thousand letters and for two hundred letters, so that one might get an idea how often to expect to find given letters in both long and short messages or documents.