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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 and Turkish the letter }, elif, corresponding to the French stopped or silent h, occurs oftenest. In Chinese—at least, in the newspapers—the characters found in order of frequency are 7 (chi, of, genitive), 4 (puh, not, negative), and J (kong, work). ‘To ascertain which letters occur oftenest in any language, one must “calculate fre- quencies.”
The next thing to do is to study which letters most commonly adjoin. They are es in French and en in German. The most frequent groups of three are ent in French, the in English, em in German, che in Italian, ete. Bulky works have been written on this subject containing long lists, more or less complete, of the various articula- tions and disarticulations of words. Of course, this requires an enormous amount of labour, involving a
4 CRYPTOGRAPHY
statistical study of texts containing many thousands of letters.
T'o revert to our example, I encountered a difficulty at the first onset. The sign which came second in order of frequency, and which I supposed! should represent either ” or s, caused me some embarrassment.
At last I abandoned the books I had been using, and began a new calculation of the frequency of letters in certain authors and French newspapers. In the letters of Voltaire I noted that the letter w occupied the second place in point of numbers, this being obviously due to the fact that the words nous and vous (“ we” and “ you ”’) are common in the epistolary and conversational style.
In the sixth line of the document, a group of signs offered the peculiarity of conjoining twice in succession the two most frequent characters, the supposed e and the supposed u, separated by another sign and followed by one occurring rather rarely. Accordingly a new trial was made, which this time proved satisfactory. These sions might imply the tail of the word valeureuz or the words pewreux or hewreux. This last proved to be correct.
Among the first signs of our example, the supposed e occurs preceded by the supposed uw. In French, w fol- lowed by e occurs principally in the syllable que. It could not be the word lequel here, the sixth sign not being similar to the first. The group must read: Ce que. A little farther on we meet again with the sign represent- ing ¢, followed by the r of the word heureux and preceded by e, a group of letters which might, for instance, form the words écran, décret, or, better still, écrire.
1 The decipherment is based not only on statistics, but also on
hypotheses. In fact, the famous expression, “‘ Suppose that .. .,”’ is the motto of the cryptographer
PRINCIPAL SYSTEMS OF CRYPTOGRAPHY 5
The result of the deciphering showed that there was no question of a conspiracy in this mystical writing, but of the enthusiastic sentiments inspired in the author by some charming person met at a fashionable party. It was, perhaps, the rough draft of a letter. The first phrase, translated, was as follows:
“ What I am writing you here is merely to relieve my heart, since I am writing to the dearest object in my life to divert the frightful restlessness of my days... .” |
And so on for twenty-five lines.
Cryptography has provided an entertaining field for novelists. They produce heroes who mark in secret writing the route to be followed in order to recover a fabulous treasure or to track the author of a crime, or perhaps learned men who reveal some stupefying dis- covery.
We have all read the story of the Gold Beetle, by the American novelist, Edgar Allan Poe. It will be remembered that, in order to recover the wealth buried by Kidd, the pirate, it was necessary to let the gold beetle fall from the left orbit of a skull attached to the highest branch of a big tree, and to extend by fifty steps a line leading from the foot of the tree and passing through the point where the beetle fell. A hole was dug at the spot reached, and, of course, an incalculable treasure unearthed.
Who has not read, also, Jules Verne’s Jangada ? And who has failed to be interested in the researches made by the Judge Jarriquez into a Portuguese document in secret writing in order to save the life of an innocent victim condemned to death ?
In A Voyage into the Interior of the Earth, also by Jules Verne, we see a Danish scholar intent on piercing
6 CRYPTOGRAPHY
the mystery of a cryptographic parchment which is to reveal the route to be followed in order to penetrate into the depths of our terrestrial globe. But old Professor Lidenbrock seeks too far, and it is his nephew Axel, a careless young man, who attains the object simply enough by reading the finals of the lines backwards.
It may be pointed out that the system deciphered by Hdgar Allan Poe is comparatively simple. He himself acknowledges this, and claims to have deciphered keys* “ten thousand times’? more arduous. The system conceived by Jules Verne in his A Voyage into the Interior of the Earth is also very easy. As to that in Jangada, the problem is solved, thanks to an incredible combination of favourable circumstances.
In one of the latest novels of the Arséne Lupin series, The Hollow Needle, Maurice Leblanc has the idea of uniformly substituting the consonants of a document by dots. Nothing can be said of this system, except that it is ultra-fantastical.
A final example, and this time historical: the poet Philippe Desportes wrote in cipher the life of Henri III., King of France. If this work had come down to us and been deciphered, probably not many edifying subjects would have been found therein. But it was burnt during the troubles of the Holy League.?
Some months ago I received a letter from a foreigner, who informed me that he was very interested in erypto- graphy, and that he wanted to work on some official texts. He begged me to lend him some diplomatic documents, of which he would take copies for his use
* The “key” in cryptography is the formula which enables a text in cipher to be read. * Henri Martin, Histoire de France, vol. ix., p. 472, note.
PRINCIPAL SYSTEMS OF CRYPTOGRAPHY 7%
and return me the originals. ‘‘ You do not know me,”’ he wrote, “but you can rely on me entirely: I am neutral.”
Despite this excellent recommendation, I had nothing to communicate. However, touched by his candour, I gave him some advice. Living in a large town, he had at hand a mine of small cryptograms: he had only to look in the windows of the curio dealers and antiquaries, take note of a number of prices marked in secret characters, and try to decipher them. It is a crypto- graphic exercise as good as any other. There are certain methods which enable one to guess which letter means 5, which 0, which 9, ete. I refrained from pointing them out to him, since the value of these exercises lies precisely in finding out these methods for oneself. I wonder whether he followed my advice, which I consider was good.
* * * *
We were just now recalling some specimens of secret writing where the key was in the hands of only one person. Let us now consider another order of cryptography, which enables two persons to correspond under shelter of secrecy. We will leave aside the various sympathetic inks, the employment of which affords no security, whether used on paper, or, as has often been seen in the course of the present war, on the skin—that of the arms or back—since a simple chemical reaction exposes them immediately. Conventional or shuffled alphabets alone are of any use.
An example of a cryptography widely in vogue in the
1 Note By TRANSLATOR.—This is for decimal currency. In ciphers representing £ s. d., the same methods would first disclose 6, 1, and 0.
8 CRYPTOGRAPHY
Middle Ages is furnished by the so-called alphabet of the Freemasons, of which the following is a specimen:
The following words will be read without difficulty: CE SEIS ee
By writing the alphabet in a different order, the values of these angles and squares may be altered at will.
In December, 1916, I was given a bundle of papers in Spanish cryptography to decipher. It was a private correspondence written in the above system, a little complicated: there was not only one dot, but two or three in most of the letters.
Among many other ingenious systems may be men- tioned that known as the “ zigzag,” which is constructed thus: Take a sheet of paper ruled in squares, and write along the top of the vertical columns the whole alphabet in any order you like. Having done this, superpose on the page a sheet of tracing paper, on which mark a dot in the vertical column headed by the letter required, taking care not to mark more than one dot at a time in each horizontal line. The dots once marked, you join them by zigzag lines, and send your correspondent the drawing thus obtained.
PRINCIPAL SYSTEMS OF CRYPTOGRAPHY 9
_An inquisitive intermediary would see nothing in it, especially if the document were brief, whereas the recipient will place the message received on to a graph similar to that of the sender, and will have no difficulty in deciphering:
PEC tOGxXDERKY J LS ZVM-T AU GN BOHW
“ T love you dearly.”
He (or she) will reply in the same way, or perhaps by means of a thread. This is laid along the cipher alphabet, beginning on the left, and wherever the thread passes a | letter required, it is marked in ink. Arrived at the right extreme of the alphabet, the thread is moved a section, and a new start is made from the left, and so on in- definitely until all the letters required have been marked. Thus, to write the words “ I reciprocate’ would require something over seven sections of the thread, each cor- responding to the length of the alphabet.* This method
1 Tt is needless to say that if the zigzag contains fifty angles and
the thread bears fifty marks, a decipherer could discover the key of both. |
10 , CRYPTOGRAPHY
of corresponding is very ancient. It is some 2,300 years since Aineas, the tactician, recommended a similar system in his Polhorcetes.*
Shorthand is not the same thing as cryptography, of course; it is not a secret writing, seeing that hundreds of thousands of persons can make use of it. Nevertheless, an artful mind can combine shorthand and cryptography in such a way as to form a fairly complicated secret writing. In 1913 I was handed several dozen pieces of paper which had been seized at a penal establishment in French Switzerland. ‘They were covered with shorthand- like characters which had resisted the efforts of several professional shorthand writers. Here is a fragment:
Ol! Sl Wh et ee
It was the correspondence of two bandits, authors of robberies on a high seale, who were interned at the two extremes of the prison. They had transmitted their missives by means of a very well organised postal service. Their letter-box was purely and simply the backs of the volumes lent them by the prison library. They had agreed in advance as to what books they would borrow, and each found the letter of the other by opening the book wide, which allowed the little piece of paper con- cealed in the hollow space in the back of the binding to fall out.
They had other hiding-places all ready in case of alarm. Their alphabet consisted of more than 200 different signs.2 I will dwell a moment on the contents of these
1 Chapter xxxi.
2 The method of deciphering applied here was to calculate the frequency of the various lines and curves.
PRINCIPAL SYSTEMS OF CRYPTOGRAPHY 11 messages in order to show the usefulness of a safe form of cryptography.
These two bandits, M. and S., had drawn up well- schemed plans of escape, and were on the eve of carrying them out when the unforeseen contingency of the decipher- ing occurred. They had organised their future move- ments, and projected the burglary. of a jeweller’s shop in an important Swiss town in order to get on their feet before proceeding to effect a gigantic coup at a jeweller’s in the Rue de la Paix, Paris, or in Regent Street, London,
‘“Take the small cases,’ wrote M. to §., “ but never jewels displayed on velvet trays, for jewellers have a trained eye, and can at a glance detect whether any piece is missing from a tray. The large dealers always have an assistant concealed in a corner, whose duty it is to keep his eyes fixed on a mirror in the ceiling, enabling him to watch most of the shop without the knowledge of the customer. When you go into the shop, find out, without attracting attention, where this mirror is situated, and operate outside its radius of reflection.”
Some further advice followed:
‘“T should work in first-class railway-carriages: operate on solitary individuals, but never with a dagger, you understand; nor with revolver or chloroform. Hypnotism at all times and everywhere. So lose no time in taking lessons in hypnotism as soon as you have left this en- chanting resort.”’ |
M., who had a taste for mental pursuits and was well read, mingled the practical advice which we have just read with philosophical considerations on perfect friend- ship, on Schopenhauer and Nietzsche, on the destiny of the soul, etc. Occasionally there is a postscript: ‘ Ask our worthy chaplain to borrow my fountain-pen for you.
12 CRYPTOGRAPHY
I will conceal a watch-spring in it, toothed like a saw, and you can begin on filing the bars of your cell, for we shall have to be out by the end of the month.” He further writes: “‘ Not one out of a hundred shorthand experts in Berlin—not one, I repeat—would be capable of reading my system Sto. So it 1s still more likely to remain a sealed book in French Switzerland.”
The example given above in facsimile means: “* Be on the alert! The pincers will be put behind the window- sill this afternoon.” Its actual reading is: “ Achtung ! Zange wird nachmittags am Fenstersims hinterlegen.”’ For this correspondence took place in German. I have chosen this phrase from a sample which begins with a succession of oaths of no particular interest for us.
if.
As we have seen, cryptography is of service to private individuals—that is, to certain private individuals—but its main usefulness lies in furnishing a means of cor- respondence between heads of States, Ministers, and Generals. In wartime, especially, by its aid plans of action and secret information can be communicated, relief asked for, ete. Cryptography, when employed for diplomatic or mulitary purposes, is termed “ cipher,” whether it be in the form of ciphers or figures, letters, or any other signs. Obviously, when war conditions prevail, only Government departments and military authorities are in a position to utilise cryptography,’ which is of incalculable value to them.
1 The author should have said “legitimately.” It is a matter of common knowledge that numberless attempts were made by spies to convey information to the enemy by means of more or less ingenious ciphers. In most cases these attempts were foiled by the ingenuity of the expert staff of cryptographers employed in the various Cipher Departments.—TRANSLATOR.
PRINCIPAL SYSTEMS OF CRYPTOGRAPHY 18
IIT.
The origin of secret writing is lost in the mists of anti- quity. To go back only to 500 years before the Christian era, we find this record: “‘ When Xerxes planned to invade Greece, a Greek named Demaratus, a refugee at the Court of the King at Susa, warned his countrymen of Lacedemon by means of a message traced on wooden tablets covered with wax. At first nothing could be seen on them, and it was Gorgo, the wife of Leonidas the King, who discovered the stratagem.”! The Cartha- ginians made use of a similar process, which seems to indicate the employment of sympathetic ink.? Hero- dotus® has recorded for us a not very practical system which was once employed in the Hast. “ Histieus, tyrant of Susa,” he tells us, “‘ wishing to communicate to Aristagoras, his heutenant at Miletus, the order to revolt, could find only one way, all the roads being guarded. He had the head of his most trustworthy servant shaved, made some incisions in the scalp, and waited till the hair grew again.” (The era of the tele- graph had not yet arrived!) ‘‘ As soon as this occurred, he sent the man to Miletus without giving him any further instruction than, on his arrival, to invite Aristagoras to shave his head and scrutinise it. Now, the incisions formed the word ‘ Revolt ’ (Avoataats).”’
This rather slow means of correspondence was not in current use. At the same period the Spartans had a far better system of cryptography, the scytales, of which
1 Herodotus, VII. 239.
2 Aulu-Gelle, Nwits attiques, XVII. 9. ou Wi, eno
14 CRYPTOGRAPHY
Plutarch,t among others, has left us a description. The scytale was a cylindrical rod round which the sender of the secret message rolled a long band of papyrus in a spiral, after the fashion of the emblems which cover reed- pipes. On the wrapper thus formed he traced the words lengthwise along the rod, taking care to write only one letter at a time on each fold of the ribbon of papyrus. Once unrolled, this showed nothing but a meaningless succession of separate letters. The recipient rolled the band round a rod of the same length and diameter as that of the sender. The sheghtest difference in the diameter of the two rods made the reading of the message practically impossible.
To give an idea of the difficulty involved in deciphering these scytales without having the proper rod, or with a cylinder of a size dissimilar to that of the sender, it may . be stated that twenty letters can be combined in 2,500 billions of different ways. A decodist who applied himself to discovering the meaning of a document thus transposed, and was so expeditious as not to devote more than one second to the serutiny of each combination, would reach the trial of the final arrangement of these characters at the end of 75,000,000,000 years. If chance favoured him, he might hit upon the solution at the thousand and first or ten thousand and first trial, or it. might happen that he would have to persevere to nearly the end, or, worse still, he might encounter the solution without knowing it and stopping there.
Nowadays, however, there is a process which enables us to decipher these ribbons of papyrus comparatively easily, even without being in possession of the desired
1 Life of Lysander, ch. xix.
PRINCIPAL SYSTEMS. OF CRYPTOGRAPHY: 15
cylinder. Let us suppose that one of these messages has fallen into our hands, and that its twenty-five centuries of age have left it preserved in its original state of fresh- ness. We begin by making an exact copy, which we shall manipulate in our own way, bearing in mind always to leave the originals intact. From one of the ends of this copy let us cut off, say, three fragments, each con- taining ten or a dozen letters, or more or less if we like. We place these segments one beside the other in the order in which we have cut them. This done, we slide the second along the first, either up or down, and the third along the second, endeavouring to form possible syllables or fragments thereof. (Assume, for convenience, the document to be in English.) Let us suppose that after various adjustments.our attention is fixed. on the following combination:
We observe that of the two groups /D of three letters, W 1 L is capable of |
. i forming a part of the word will or | | Wilde Lo test this; we reter to the |# By original scroll to count the intervals }AIR
between the three letters in the Iwi I
another L or a D,.we are on the right track. The trial proves this to be the case by yielding L. We now make a new copy of the papyrus and cut it into segments of eleven letters, which we place one by one to the right, the result being that the document becomes an open page to us, thus:
L eroup, and find that I is the eleventh | letter after W, and L the eleventh Tyr H after I. It now becomes obvious ITiN| that if the eleventh letter after L is g 'p
12
Sia
16 CRYPTOGRAPHY
D fe HE.) Bie. nay oo aes A\ Rid. t the. e*nremmig: Wil tia: ee eee | Eee eee Sa os ai r.|1 Nila. we 6 k. a amen 118.) Pole na ae eet
7
L
Drawing nearer the Christian era, we are told by Suetonius, the biographer of Julius Cesar, that the latter “employed for seeret matters a sort of cipher which con- sisted in writing, instead of the required letter, the third letter from it, as D for A, and so on.’’!
“The Emperor Augustus,” says the same historian, ‘when he writes in cipher, puts B for A, C for D, and so on for the other letters, and AA for Z.’”
Julius Cesar’s cipher is still in use in our day—that is to say, it remains in principle, but with complications which make it much harder to decipher. Alfred L., King of England, and Charlemagne also used crypto- graphy for corresponding with their officers. I do not think I am violating a diplomatic secret, a thousand years having elapsed, in revealing that m Charlemagne’s
secret writing ] meant 2; ie d; \ l,
Cesar, ch. lvi. 2 Augustus, ch. |xxxviil.
‘6
PRINCIPAL SYSTEMS OF CRYPTOGRAPHY 17
ete.| The Governments of Venice, Florence, and other Italian republics made use of secret writing from the thirteenth century.
Since the Middle Ages numerous investigators have pondered over an ideal system of cryptography. Among them we may mention Francis Bacon, the philosopher, and Blaise de Vigenére, the French diplomatist, whose ingenious table is still useful to-day, either for coding or decoding. Cardinal Richelieu, the great statesman, frequently resorted to cryptography. Louis XIV. used so complicated a cipher for corresponding with his Ministers when they were absent from Versailles, or when he himself was with the army, that it was not until 175 years after his death that the key was discovered.
Let us here pause in this historical survey to examine more closely the part played by ciphers. Nowadays all the Great Powers have a Cipher Department. There is one in London, and others at Paris, Rome, Petrograd, Berlin, Vienna, and elsewhere. When the head of a State and his Minister of Foreign Affairs leave the country, they are always accompanied by a staff of experts from the Cipher Department. M. Poincaré, during his last journey to Russia, a few days before the German aggression, had with him the Director of the French Cipher Depart- _ ment, with whose collaboration he was able to keep in touch with Paris without running the risk of indiscreet confidences.
Germany has a department, the Chiffrierburo, staffed by professional experts, whose mission is to find new ciphers, both complicated and safe, and to decipher the secret documents of the enemy. ‘The newspapers in-
1 G. Selenus, Cryptomenice, p. 282 (Alcuin). ; 2
18 CRYPTOGRAPHY
formed us that in February, 1916, the Department at Vienna employed twenty-six cryptographers.
“ Cryptography,” said one of the most genial of Swiss Army commanders to me the other day, “is a German science. You must be a German, wear gold spectacles and a bushy beard, before one can properly study cryptography.”
Not so long ago, however, when neither Berlin nor Vienna were capable of deciphering difficult cryptograms, they were glad, on occasion, and in secret, to have re- | course to one of those little States which they so utterly despise.?
Kach step in the progress of cryptography 1s accom- panied by a corresponding step in the art of deciphering.
History has preserved the names of some celebrated decodists. Thus, the geometrician Francois Viete suc- ceeded in deciphering for Henry IV. a very complicated system, formed of some five hundred signs, which was _ used by the heads of the Holy League and the Spaniards.? The latter, angrily denounced Viéte to the Holy See as a wizard and a necromancer. According to them, he could only have entered into possession of the secret by calling up the spirits of those who had known the cipher during their earthly career. But the Pope was a man of humour: he submitted the plaint to examination by a commission of Cardinals, “‘ with urgent recommendation.” The Cardinals understood the hint, and the examination is still unfinished.
1 See the Ziircher Post, February 28, 1916, midday edition, and the Bund, February 29, 1916, Sup. No. 100. The military Court at Zurich, after seeming to hesitate subjectively over this point in a paragraph of its judgment, admitted it objectively in another
paragraph. 2 De Thou, Histoire universelle, Book 129, year 1603.
PRINCIPAL SYSTEMS OF CRYPTOGRAPHY 19
During the reign of Louis XIII. another decodist, Antoine Rossignol, made himself known, to the dis- comfiture of the Huguenots.
“Tt was in the year 1626,” says Charles Perrault,’ “at the siege of Réalmont, a city of Languedoc, then in possession of the Huguenots, that he first gave proof otf his talent. The city was besieged by the army of the King, commanded by the Prince de Condé, and it opposed such a resistance that the Prince was on the point of raising the siege, when a letter from the besieged was intercepted, written in cipher, of which the most skilful in the art of deciphering could make nothing. It was given to M. Rossignol, who deciphered it forthwith, and said that the besieged were sending to the Huguenots of Montauban to say that they were short of powder, and that if they were not supplied with some immediately they would surrender to the enemy. The Prince de Condé sent the besieged their letter deciphered, with the result that they surrendered the same day. Upon this being reported to Cardinal Richelieu, he invited M. Ros- signol to the Court, and the latter gave such astonishing proofs of his skill that the great Cardinal, despite that extraordinary disposition which prevented him from admiring many things, nevertheless could not forbear expressing his surprise. He (Rossignol) served very usefully during the siege of La Rochelle, discovering the enemy’s secrets by means of intercepted letters, all of which he deciphered with scarcely any trouble.”
He continued his activities under Louis XIV., who held him in such high esteem that once, on the way back from Fontainebleau, he called on him at his country
1 Les Hommes illustres qui ont paru pendant ce (17th) siécle. Vol. i. Antoine Rossignol, Maistre des Comptes.
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house at Juvisy to which he had retired. The poet Bois-Robert addressed many of his epistles in verse to Rossignol, in one of which, in accordance with the wishes - of Cardinal Richelieu, he extols Rossignol’s skill, regard- ing him as a redoubtable prodigy. The following is a rough translation of the passage: ‘‘ There is nought else beneath the skies
That may be hidden from thine eyes.
O what a mighty art is thine !
For by it provinces are won,
And secret plans of kings undone.
This is a right commodious art.
I prithee unto me impart
Thy methods, and thus justify
The years that be and those gone by.
The vanquished, fleeing from the fray,
Take oath a devil’s in thy pay;
Hell’s unseen imps their packets steal,
Their secrets to thine eyes reveal.”
There is a certain amount of truth underlying this extravagant eulogy, not that an Antoine Rossignol would wish it. Colonel Schaeck, of the Swiss General Staff, has stated that ‘‘a good decipherer must have both natural and acquired qualifications, the former necessarily playing a predominant part. The natural qualifications are insight, the spirit of observation, patience, and perseverance. If a person be happily gifted in any degree for this kind of work, and finds an opportunity of developing his natural talents, he may attain by study and practice a surprising degree of skill. For this he will have to devote himself to a profound study of the various systems of cryptography, have a thorough knowledge of mathematics, and especially the calculation of probabilities, and be acquainted with languages and their literatures,”
PRINCIPAL SYSTEMS OF CRYPTOGRAPHY 21
‘lwo remarks may be added to this statement: Virst, in default of mathematics, we may be satisfied with arithmetic; secondly, one thing is indispensable, which Colonel Shaeck possessed, although he modestly refrained from mentioning it—common sense. I have heard of a case where fifteen months of assiduous research failed to produce any result, while, a little later, by the exercise of a little common sense, the goal was reached in two days.
In 1645 John Wallis, the English mathematician, acting under the order of Cromwell, deciphered the secret papers of King Charles I., which were seized after the Battle of Naseby, and which proved that the King, in negotiating with his adversaries, was playing a double game.*
On July 2, 1673, Louvois, the then French Minister of War, paid 600 livres, equivalent to £120 sterling, to one Vimbois for discovering the cipher of certain con- spirators; four days later he prescribed a similar fee to the Sieur de la Tixére for a discovery of the same kind? If these lines meet the eyes of any cryptographers, they will regretfully admit that the remuneration for their arduous labours has dwindled terribly since that period.®
In 1752 a German professor named Hermann, who had defied the mathematicians and learned societies of Europe to decipher a system of his invention, saw his secret unveiled by a Swiss named Nicolas Béguelin or De Béguelin, son of the Mayor of Courtelary, a village
1 Hneyclopedia Britannica, art. Cryptography.
2 Valerio, De la cryptographie, vol. ii., p. 11.
3 The amour-propre of the cryptographer does not always meet with the respect due toit. For instance, a cryptogram which I was
charged officially to decipher in May, 1917, resolved itself into ** . . . for the fool who reads these lines.”
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situated in that part of the bishopric of Basle which was then under the Bernese Protectorate. He had required only eight days to discover the key. The story of this incident is preserved in the History of the Royal Academy of Science and Literature of Berlin.*
It was by methods used in cryptography that Minter, a Dane, and Grotefend, a German, succeeded in 1802 in deciphering a part of the alphabet of the Persian cuneiform inscriptions. One group of angles or arrow- heads struck them by its frequent repetition. Minter pronounced it to be equivalent to the word “ king ” (Ixh-shayathiya in the harmonious language of the time), and this supposition was eventually confirmed.
Mention may be made also of Bazeries, a French officer, who not long ago succeeded in deciphering Louis XIV.’s system of cryptography, comprising some 600 numbers, some of which represented letters and some syllables. Thus, for example, the word “ mine” could be written in these four ways—.e.,
Tee 7B, dee 1. Zoos -o0L* Tb. Ill. 514. 184. 3874. IV. 585. 229. 146.
and by still other figure combinations. ok * * ok *
As we have seen, cryptography has at all times been extensively used by conspirators, revolutionaries, and secret societies. On this poimt I will confine myself to the two following quotations:
‘In May, 1603, a number of foreigners used to meet in a house near Fontainebleau, which they had bought
1 Year 1758 (1765), pp. 369-389, with two plates.
PRINCIPAL SYSTEMS OF CRYPTOGRAPHY = 28
for the purpose of meeting secretly. Their plottings, however, were frustrated, as their house was raided, and among other suspicious objects were found a quantity of letters in cipher which revealed the conspiracy.’
‘“ Among the papers of the Chouannerie,” says M. G. Lenotre,” “are to be seen a number of sheets written in bizarre characters which formed the cipher used by | Georges Cadoudal and his associates at the time of the Directory and the Consulate. The key of these is known.”’
The archives of the Foreign Offices in various countries still contain eryptographic documents the keys of which are lost and the deciphering of which the eryptographers, after interminable efforts, have had to abandon—accord- ing to plan! A curious circumstance is that texts written in cipher are encountered even among the hiero- glyphs. A certain inscription of Esneh contains a profusion of crocodiles,