CODE MESSAGES

Hokitika Guardian, 4 June 1926, Page 4

CODE MESSAGES

REMARK ABLE MACHINE. (By Science Service.) If tho code mesxfig© in Edgar Allan Boo’s famous story “The Gold Bug” has been written on the machine 'lnscribed recently to Hie American Institute of Electrical Engineers at New York, Legrand would not have had such an easy time deciphering it, for tho age-old search for vi method of putting important messages into a code which cannot he interpreted without tho use of the key seems to have been achieved. The new machine was describ’d by G. S. Vern-am, engineer of the American Telegraph and Telephone Company who stated that it, had been developed for tho use of the Signal Corps ot the United Sthtes army during the war. but until recently it has been kept secret. However, one of the advantages of tho device is thlit even an unauthorised person who has full knowledge of the methods and apparatus used cannot, interpret the message without the key. In use, the sender writes tho messages on a keyboard similar to that of a typewriter, and a perforated tape results which can he used in vip 1 ' tia’smitters frequently used in lelcgrapn offices. By means of another kind of r.Jiehine, if it is desired, the cipher message can be written directly hi live letter code words on paper in ordinary characters. When the message is received, it is written on a tape in perforations, and when this is passed through the deciphering machine the message is written out in p?'in text mi a sheet of paper. The method used is one involving what is referred to as a nmltnle alphabet substitution cipher. In the aßinary .substitution cipher a ciph-r alphabet, with Ihe letters arranged in .ail arbitrary manner replaces '-lie actual alphabet ill tho same nrdr. I hat is instjid of starting A, B, C, ole. the cipher alphabet might start F, Q, R, etc. and in use the letter A in ITo original message would become F in the cipher: B would become Q and so on. Such a cipher may easily he interpreted in the way Poe made famous in “Tho Gold Bog,” hv noting the letter tl(it occurs ofteuest and calling it E, which is most used in the I.’nglish language. 0 is the next ofteuest used with T a close third, J. X, and being the least used. With the multiple nlpli i r > H. cipher, a series of cipher alphabets are use! ono after the other, the order bring given by means of the keyboard, but the same alphabet is used < or and over at regular intervals. \\ bile more difficult than the single alpha net, Ihe cipher expert, or “er.vntuiulv.sl, ’ can interpret such a message w.Hi nil He key. However, if a key as long v the niosagc itself is used and the letter:; hi it are selected at random, it is ]>rn"i.i cally impossible to translate it. lUs is tho system used in tire machine, and the key is another tape, so that the transposing of the letters is done automatically. As a further improvement-, a way was found to obviate the us? nl a tape as king as the tape of the message itself. This wtts accomplished by using two loops of tape which combined give the key. One loop is one character shorter than the other, so tlml as the two tape* pnss through the machine at the same rate of speed, they must go around many times before tho same combinations are repeated. This gives the effect of a very long tripe. Mr Vernam slated that the apparatus could also bn used lor radi i-, ol il necessary the code tape could be sent by mail without, fear of its being interpreted by an unauthorised person.