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A Fe 6 i - + -@ Re pe pe ee a = = = <e - ay eer ey pic tgt Seber etetetst Ratan ay Sago ag oe saieet at =e a2 “tans pee Bere ee eee sieirinsi tiie ‘us 3 in erp rp ras pene ee a = eer ERT LA Le a ee Ea soa ee 4 Satta tet — ' = 357 — <r ares ba = a Sea gay 35 une ra we HLL TE: is eis Sp Arm ans no stats re ara ran re HUE ak sf (di 5 AP NET LIT 9 caren ape a: ap - he supLaLelelalersds F-Pt iese oad SSS et. re Saray annem n ee ete areas rer esen z : oe be ™ Fre re carne ern ars ow ml a - a : a~ - » Po ane sitertts yet Boats atca naga cacley atante st anteater tarde = Splig gctasta ta #) SP er ers it a Q Perit oa. tele * FSS y fon ° ‘ Co uls to ber 4 J —— i ¥% Hi CRYPTOGRAPHY CRYPTOGRAPHY BY ANDRE LANCIE ERANSLATED FROM, THE (RFRENGH BY J. ©. ot. MACBETH AUTHOR OF THE MARCONI CODE,” ‘‘ MARCONI DICTIONARY, ” ETC. GOONS PADDLE Sia “COMPANY LIMITED LONDON BOMBAY SYDNEY 1922 PRINTED IN GREAT BRITAIN PREFACE I HAVE no intention of writing a complete manual of cryptography. Fimality, even very relative, is not attainable in the domain of this art. Besides, good manuals are in existence on this subject, and the titles of some of them will be found at the end of this volume. A eryptographer of considerable experience, however, can always add a few details even to the most complete works of this kind. My object in writing this book is simply to explain what cryptography is, and to recall what it has been from antiquity to the present day; in short, to relate my experiences as a decipherer. The first part of the volume contains a description of the principal systems of cryptography, together with a note on the role played by cryptography in history. In the second part I relate how I succeeded in decipher- ing a dozen cryptograms of various kinds. In some chapters of this section I give the texts just as they came into my hands; but in the majority of cases, though preserving the system of cryptography actually employed, I have, on grounds of expediency. substituted an approxi- mate reading for the actual text,and have modified the plan, and even radical features of the narrative, in such a way as to render abortive any attempt at identification and localisation. Wa vl PREFACE In the third part I give some advice in a general way on lines which have proved profitable to me, and, further, a certain number of tables and formule; but while I recognise these to be very useful, too much reliance should not be placed on them, under penalty of striking the wrong track, as I shall have occasion to repeat farther on. In point of fact, as I have found by experience, in cryptography the exceptions are infinitely more frequent than the rule. TRANSLATOR’S PREFACE I have to acknowledge with grateful thanks the valuable assistance I have received in preparing this work from the late Mr. W. Jarvis, Lieut.-Commander W. W. Smith of Washington, U.S.A., Mr. Albert M. Smoot of the Ledoux Laboratories, New York, and Miss A. Wishart of the Radio Corporation of America. It was not an easy task substituting English text for the examples of ciphers in French, and if there are any errors which have inadvertently escaped detection I humbly beg forgiveness. J.C. Be MACBET CONTENTS PART I DESCRIPTION OF THE PRINCIPAL SYSTEMS OF CRYPT- OGRAPHY, WITH HISTORICAL NOTICE PARTY II EXAMPLES OF DECIPHERING : of PAR? HI Lists AND TABLES — - x , i BIBLIOGRAPHY — - B 2 : r PART IV THE PLAYFAIR CIPHER SYSTEM, ETC. Vil PAGE 158 159 ACKNOWLEDGMENT Our thanks are due to the following gentlemen in connection with translating the book from the original French, working out and substituting English ‘‘ Examples’’ for the French ones, adding additional matter, and seeing the work through the Press: Mr. J. C. H. Macbeth. The late Mr. W. J. Jarvis. Mr. H. G. Telling. Commander Smith, U.S.N. Paymaster-Commander J. H. A. Brown, C.B.E., B.N. THE MARCONI INTERNATIONAL CODE CO., LTD. Marcont Housh, STRAND, Lonpon, W.C. 2. 25th July, 1922. CRYPTOGRAPHY | Bos 0 as a | DESCRIPTION OF THE PRINCIPAL SYSTEMS OF CRYPTOGRAPHY, WITH HISTORICAL NOTICE! if. EvERYONE has, at some time or other, used crypto- graphy,” or secret ciphers. Who has not had occasion to make some note, or to correspond with somebody, by dotting letters in a news- paper or book? Even children amuse themselves in this way on their school desks. But a pen or pencil is not necessarily required to make use of a secret language. More than one of us, in our young days, have been embarrassed by a question from the schoolmaster. We have been required to give a proper name in answer, but it is precisely this proper name which has slipped our memory. So we have glanced at a comrade with whom we had previously come to an understanding. And the latter passes a finger over his hair, his ear, his lips, his ear, and his nose, whereby we understand ‘‘ Helen.” We have thus corresponded by means of mimetic cryptography. What is cryptography, after all? Cryptography is the art of recording one’s thoughts in such a way as to 1 This Part I. appeared in the Bibliotheque wniverselle et revue suisse in August, September, and October, 1917. * From the Greek words xpumros, secret; and ypadpew, to write. 1 2 CRYPTOGRAPHY make them unreadable to others. Particularly, more- over, it enables two persons to correspond under cover of complete secrecy—at least in theory. A man will perhaps invent, on his own account, a system of writing by means of which he can write and preserve secrets which he prefers not to divulge, while ensuring the possibility of reading them again at any time. The great thinker, Alexandre Vinet, composed a system of cryptography which was as simple as he was noble- minded. He used it to note in his diary his qualms and trials. The phrases he wrote in this way can be read almost at a glance. The celebrated Swiss physiognomist, Jean-Gaspard Lavater, in his Diary pf a Self-Observer, constructed several systems of secret writing to preserve his private reminiscences. These passages, which are omitted from the new French translation, are far more difficult to read than those of Vinet. Eight years after his death his countrymen had not succeeded in deciphering them all. } Some years ago I was asked by a friend, a professor at a university in German Switzerland, to decipher a piece of yellow paper, covered with strange characters, found among the records of a Swiss politician, a contemporary of Napoleon I., and which was supposed to have some historical importance. Here 1s a specimen, a part of the first line and one word of the sixth: BY NLY3 7 Uses ae EXEL YS 1 PRINCIPAL SYSTEMS: OF CRYPTOGRAPHY. 3 My friend had consulted his colleagues: one had declared it was not Sanscrit, another that it was not Ethiopic, and still others that it was neither Slavonic nor Runic. These professors spoke truly, for it was French ! This system was one of the easiest to decipher. There were some 800 signs in the text. One of the signs, the second in the above example, and the most frequent, occurred something over ninety times, while another, the fourth, occurred seventy times. Now it is well known that in English, French, German, and most languages of Western Europe, the most fre- quently occurring letter is e; the letter which follows is, in French, » or s, according to the writer; in German, n; in English, ¢; in Italian, 7; and in Spanish, a. In Russian the most frequently occurring letter is 0, but 7 if the language 1s written in Roman characters. In Polish the most frequent consonant is z; not uncommonly three may be found in the same word. In Arabic an