As we can scarcely imagine a time when there didnot exist a necessity, or at least a desire, of transmitting informationfrom one individual to another, in such manner as to elude general comprehension;so we may well suppose the practice of writing in cipher to be of greatantiquity. De La Guilletiere, therefore, who, in his "Lacedaemon Ancientand Modern," maintains that the Spartans were the inventors of Cryptography,is obviously in error. He speaks of the scytala as being the originof the art; but he should only have cited it as one of its earliest instances,so far as our records extend. The scytalae were two wooden Cylinders,prccisclv similar in all respects. The general of an army, in going uponany expedition, received from the ephori one of these cylinders, whilethe other remained in their possession. If either party had occasion tocommunicate with the other, a narrow strip of parchment was so wrappedaround the scytala that the edges of the skin fitted accuratelyeach to each. The writing was then inscribed longitudinally, and the epistleunrolled and dispatched. If, by mischance, the messenger was intercepted,the letter proved unintelligible to his captors. If he reached his destinationsafely, however, the party addressed had only to involve the second Winderin the strip to decipher the inscription. The transmission to our own timesof this obvious mode of cryptography is due, probably, to the historicalusesof the scytala, rather than to anything else. Similar means of secretintercommunication must have existed almost contemporaneously with theinvention of letters.
It may be as well to remark, in passing, that innone of the treatises on the subject of this paper which have fallen underour cognizance, have we observed any suggestion of a method — other thanthose which apply alike to all ciphers — for the solution of the cipherby scytala. We read of instances, indeed, in which the interceptedparchments were deciphered; but we are not informed that this was everdone except accidentally. Yet a solution might be obtained with absolutecertainty in this manner. The strip of skin being intercepted, let therebe prepared a cone of great length comparatively--say six feet long--andwhose circumference at base shall at least equal the length of the strip.Let this latter be rolled upon the cone near the base, edge to edge, asabove described; then, still keeping edge to edge, and maintaining theparchment close upon the cone, let it be gradually slipped towards theapex. In this
Few persons can be made to believe that it is not quite an easy thingto invent a method of secret writing which shall baffle investigation.Yet it may be roundly asserted that human ingenuity cannot concoct a cipherwhich human ingenuity cannot resolve. In the facility with which such writingis deciphered, however, there exist very remarkable differences in differentintellects. Often, in the case of two individuals of acknowledged equalityas regards ordinary mental efforts, it will be found that, while one cannotunriddle the commonest cipher, the other will scarcely be puzzled by themost abstruse. It may be observed, generally, that in such investigationsthe analytic ability is very forcibly called into action; and, for thisreason, cryptographical solutions might with great propriety be introducedinto academies, as the means of giving tone to the most important of thepowers of mind.
Were two individuals, totally unpractised in cryptography, desirousof holding by letter a correspondence which should be unintelligible toall but themselves, it is most probable that they would at once think ofa peculiar alphabet, to which each should have a key. At first it would,perhaps, be arranged that a should stand for z, b for y, c for x,dforw, &c. &c.; that is to say, the order of the letters would be reversed.Upon second thoughts, this arrangement appearing too obvious, a more complexmode would be adopted. The first thirteen letters might be written beneaththe last thirteen, thus:
n o p q r s t u v w x y zand, so placed, a might stand for n and n for a, o for band b for a, &c. &c. This, again, having an air of regularity whichmight be fathomed, the key alphabet might be constructed absolutely atrandom.
a b c d e f g h i j k I m;
Thus, a might stand for p
b " " " x
c " " " u
d " " " o, &c.
The correspondents, unless convinced of their errorby the solution of their cipher, would no doubt be willing to rest in thislatter arrangement, as affording full security. But if not, they wouldbe likely to hit upon the plan of arbitrary marks used in place of theusual characters. For example,
( might be employed for aA letter composed of such characters would have an intricateappearance unquestionably. If, still, however, it did not give full satisfaction,the idea of a perpetually shifting alphabet might be conceived, and thuseffected. Let two circular pieces of pasteboard be prepared, one abouthalf an inch in diameter less than the other. Let the centre of the smallerbe placed upon the centre of the larger, and secured for a moment fromslipping; while radii are drawn from the common centre to the circumferenceof the smaller circle, and thus extended to the circumference of the greater.Let there be twenty-six of these radii, forming on each pasteboardtwenty-six spaces. In each of these spaces on the under circle write oneof the letters of the alphabet, so that the whole alphabet be written--if at random so much the better. Do the same with the upper circle. Nowrun a pin through the common centre, and let the upper circle revolve,while the under one is held fast. Now stop the revolution of the uppercircle, and, while both lie still, write the epistle required; using fora that letter in the smaller circle which tallies with a in the larger,for b that letter in the smaller circle which tallies with binthe larger &c. &c. In order that an epistle thus written may beread by the person for whom it is intended, it is only necessary that heshould have in his possession circles constructed as those just described,and that he should know any two of the characters (one in the under andone in the upper circle) which were In juxta-position when his correspondentwrote the cipher. Upon this latter point he is informed by looking at thetwo initial letters of the document, which serve as a key. Thus, if hesees a m at the beginning, he concludes that, by turning his circlesso as to put these characters in conjunction, he will arrive at the alphabetemployed.
. " " " b
: " " " c
; " " " d
) " " " e &c.
At a cursory glance, these various modes of constructinga cipher seem to have about them an air of inscrutable secrecy. It appearsalmost an impossibility to unriddle what has been put together by so complexa method. And to some persons the difficulty might be great; but to others--tothose skilled in deciphering--such enigmas are very simple indeed. Thereader should bear in mind that the basis of the whole art of solution,as far as regards these matters, is found in the general principles ofthe formation of language itself, and thus is altogether independent ofthe particular laws which govern any cipher, or the construction of itskey. The difficulty of reading a cryptographical puzzle is by no
In the discussion of an analogous subject, in oneof the weekly papers of this city, about eighteen months ago, the writerof this article had occasion to speak of the application of a rigorousmethodinall forms of thought--of its advantages--of the extension of its use evento what is considered the operation of pure fancy--and thus, subsequently,of the solution of cipher. He even ventured to assert that no cipher, ofthe character above specified, could be sent to the address of the paper,which he would not be able to resolve. This challenge excited, most unexpectedly,a vend lively interest among the numerous readers of the journal. Letterswere poured in upon the editor from all parts of the country; and manyof the writers of these epistles were so convinced of the impenetrabilityof their mysteries, as to be at great pains to draw him into wagers onthe subject. At the same time, they were not always scrupulous about stickingto the point. The cryptographs were, in numerous instances, altogetherbeyond the limits defined in the beginning. Foreign languages were employed.Words and sentences were run together without interval. Several alphabetswere used in the same cipher. One gentleman, but moderately endowed withconscientiousness, inditing us a puzzle composed of pot-hooks and hangersto which the wildest typography of the office could afford nothing similar,went even so far as to jumble together no less than seven distinct alphabets,withoutintervals between the letters, or between the lines. Many of thecryptographs were dated in Philadelphia, and several of those which urgedthe subject of a bet were written by gentlemen of this city. Out of, perhaps,one hundred ciphers altogether received, there was only one which we didnot immediately succeed in resolving. This one we demonstratedtobe an imposition--that is to say, we fully proved it a jargon of randomcharacters, having no meaning whatever. In respect to the epistle of theseven alphabets, we had the pleasure of completely nonplus-ingitsinditer by a prompt and satisfactory translation.
The weekly paper mentioned, was, for a period ofsome months, greatly occupied with the hieroglyphic and cabalistic-lookingsolutions of the cryptographs sent us from all quarters. Yet with the exceptionof the writers of the ciphers, we do not believe that any individuals couldhave been found, among the readers of the journal, who regarded the matterin
A very common, and somewhat too obvious mode of secretcorrespondence, is the following. A card is interspersed, at Irregularintervals, with oblong spaces, about the length of ordinary words of threesyllables in a bourgeois type. Another card Is made exactly coinciding.One is in possession of each party. When a letter is to be written, thekey-eard is placed upon the paper, and words conveying the true meaninginscribed in the spaces. The card is then removed and the blanks filledup, so as to make out a signification different from the real one. Whenthe person addressed receives the cipher, he has merely to apply to ithis own card, when the superfluous words are concealed, and the significantones alone appear. The chief objection to this cryptograph is the difficultyof so filling the blanks as not to give a forced appearance to the sentences.Differences, also, in the handwriting, between the words written in thespaces, and those inscribed upon removal of the card, will always be detectedby a close observer.
A pack of cards is sometimes made the vehicle ofa cipher, in this manner. The parties determine, in the first place, uponcertain arrangements of the pack. For example: it is agreed that, whena writing is to be commenced, a natural sequence of the spots shall bemade; with spades at top, hearts next, diamonds next, and clubs last. Thisorder being obtained, the writer proceeds to inscribe upon the top cardthe first letter of his epistle, upon the next the second, upon the nextthe third and so on until the peek is exhausted, when, of course, he willhave written fifty-two letters. He now shuffles the pack according to apreconcerted plan. For example: he takes three cards from the bottom andplaces them at top, then one from top, placing it at bottom, and so on,for a given number of times. This done, he again inscribes fifty-two charactersas before, proceeding thus until his epistle is written. The pack beingreceived by the correspondent, he has only to place the cards in the orderagreed upon for commencement, to read, letter by letter, the first fifty-twocharacters as intended. He has then only to shuffle in the manner pre-arrangedfor the second perusal, to decipher the series of the next fifty-two letters--andso on to the end. The objection to this cryptograph lies in the natureof the missive. A pack of cards, sent
An unusually secure mode of secret intercommunicationmight be thus devised. Let the parties each furnish themselves with a copyof the same edition of a book--the rarer the edition the better--as alsothe rarer the book. In the cryptograph, numbers are used altogether, andthese numbers refer to the locality of letters in the volume. For example--acipher is received commencing, 121-6-8. The party addressed refers to page121, and looks at the sixth letter from the left of the page in the eighthline from the top. Whatever letter he there finds is the initial letterof the epistle--and so on. This method is very secure; yet it is possibletodecipher any cryptograph written by its means--and it is greatly objectionableotherwise, on account of the time necessarily required for its solution,even with the key-volume.
It is not to be supposed that Cryptography, as aserious thing, as the means of imparting important information, has goneout of use at the present day. It is still commonly practised in diplomacy;and there are individuals, even now, holding office in the eye of variousforeign governments, whose real business is that of deciphering. We havealready said that a peculiar mental action is called into play in the solutionof cryptographical problems, at least in those of the higher order. Goodcryptographists are rare indeed; and thus their services, although seldomrequired, are necessarily well requited.
An instance of the modern employment cipher is mentionedin a work lately published by Messieurs Lea & Blanchard, of this city--"Sketchesof Conspicuous Living Characters of France." In a notice of Berryer, itis said that a letter being addressed by the Duchess de Berri to the legitimistsof Paris, to inform them of her arrival, it was accompanied by a long notein cipher, the key of which she had forgotten to give. "The penetratingmind of Berrver," says the biographer, "soon discovered it. It was thisphrase substituted for the twenty-four letters of the alphabet--Le,gouvernementprovisoire."
The assertion that Berryer "soon discovered the keyphrase,"merely proves that the writer of these memoirs is entirely innocent ofcryptographical knowledge. Monsieur B. no doubt ascertained the key-phrase;but it was merely to satisfy his curiosity, after the riddle had beenread. He made no use of the key in deciphering. The lock was picked.
In our notice of the book in question (publishedin the April number of this Magazine) we alluded to this subject thus--
"The phrase 'Le, gouvernement provisoire' is French,and the note in cipher was addressed to Frenchmen. The difficulty of decipheringmay well be supposed much greater, had the key been in a foreign tongue;yet any one who will take the trouble
This challenge has elicited but a single response,which is embraced in the following letter. The only quarrel we have withthe epistle, is that its writer has declined giving us his name in full.We beg that he will take an early opportunity of doing this, and thus relieveus of the chance of that suspicion which was attached to the cryptographyof the weekly journal above-mentioned--the suspicion of inditing ciphersto ourselves. The postmark of the letter is Stonington, Conn.
SIR: — In the April numberof your magazine, while reviewing the translation by Mr. Walsh of "Sketchesof Conspicuous Living Characters of France," you invite your readers toaddress you a note in cipher, "the key phrase to which may be either inFrench, Italian, Spanish, German, Latin or Greek," and pledge yourselffor its solution. My attention being called, by your remarks, to this speciesof cipher-writing, I composed for my own amusement the following exercises,in the first part of which the key-phrase is in English — in the secondin Latin. As I did not see, (by the number for May,) that any of your correspondentshad availed himself of your offer, I take the liberty to send the enclosed,on which, if you should think it worth your while, you can exercise youringenuity.
Cauhiif and ftd sdBtirf ithot tacd wade rdchfdr tinfuaefshffheo fdoudf hetiusafhie tuis fed herhchriai fi aciftdu wn sdaefit iuhfheo hiidohwid wn acn deodsf ths tin iris hf iaf iahoheaiin rdffhedr;aer Ad auf it ftif fdoudfin oissichoaPheo hefdiihodeod taf wade odeduaiinfdusdr ounsfiouastn. Sacn fsdohdf it fdoudf iuhfheo idud weiie fi ftd aeohdeff;fisdDhsdf, A fiacdf tdar iaf ftacdr aer ftd ouiie iuhffde isle ihtt fisdherdhwid oiiiuheo tiihr, atfdu ithot tahu wdheo sdushffdr fi ouii aoahe,hetiusafbie oiiir wd fuaefshffdr ihEt ihffid raeodu ftaf rhfoicdun iiiirhefid iefhi ftd aswiiafiun dshffid fatdin udaotdr hff rdffheafhie. Ounsfiouastntiidcdu siud suisduin dswuaodf Stied sirdf it iuhfLeo ithot and uderdudridohwid iein wn sdaef it fled desiaeafiun wdn ithot sawdf weiie ftd udaifhoehthoafhie it ftd onstduf dssiindr fi hff siffdffiu.
Ofoiioiiaso ortsiii sov eodisoioe afduiostifoi fitiftvi si tri oistoiv oiniafetsorit ifeov rsri inotiiiiv ridiiot, irio riwioeovit atrotfetsoria aioriti iitri If oitovin tri aetifei ioreitit sov usttoioioittstifo dfti aSdooitior trso ifeov tri dfit otftSeov softridi fitoistoivoriofiforiti suitteii viireiiitifoi fit tri iarfoisiti, iiti trir net otiiiotivuitfti rid lo tri eoviieeiiiv rfasueostr fit rii dftrit tfocei.
In the solution of the first of these ciphers wehad little more than ordinary trouble. The second proved to be exceedinglydifficult, and it was only by calling
"Various are the methods which have been devisedfor transmitting secret information from one individual to another, bymeans of writing, illegible to any except him for whom it was originallydesigned; and the art of thus secretly communicating intelligence has beengenerally termed cryptography. Many species of secret writing wereknown to the ancients. Sometimes a slave's head was shaved, and the crownwritten upon with some indelible coloring fluid; after which the hair beingpermitted to grow again, information could be transmitted with little dangerthat discovery would ensue until the ambulatory epistle safely reachedits destination. Cryptography, however, pure, properly embraces those modesof writing which are rendered legible only by means of some explanatorykey which makes known the real signification of the ciphers employed toits possessor."
The key-phrase of this cryptograph is--"A word tothe wise is sufficient."
The second is thus translated--
"Nonsensical phrases and unmeaning combinationsof words, as the learned lexicographer would have confessed himself, whenhidden under cryptographic ciphers, serve to perpdex the curiousenquirer, and baffle penetration more completely than would the most profoundapothemsoflearned philosophers. Abstruse disquisitions of the scholiasts, were theybut presented before him in the undisguised vocabulary of his mother tongue"
The last sentence here (as will be seen) is brokenoff short. The spelling we have strictly adhered to. D, by mistake, hasbeen put for I in perplex.
The key-phrase is--"Suaviter ir, mode, fortiter I'll ret"
In the ordinary cryptograph, as will be seen in reference to most ofthose we have specified above, the artificial alphabet agreed upon by thecorrespondents, is employed, letter for letter, in place of the usual ornatural one. For example:-- two parties wish to communicate secretly. Itis arranged before parting that
( shallstand for aNow the following note is to be communicated--
) —————— " b
—— —————— " c
* —————— " d
. —————— " e
’ —————— " f
; —————— " g
: —————— " h
? —————— " i or j
! —————— " k
& —————— " l
0 —————— " m
‘ ——————" n
† —————— " o
‡ —————— " p
¶ —————— " q
] —————— " s
[ —————— " t
£ —————— " u or v
$ —————— " w
¿ —————— " x
¡ —————— " y
These words would be written thus
$ 0 . £ ] [ ] . . ¡ † £ ? 0 0 . * ¿ ) [ . & ¡ £ ‡ † ‘ ) 0 ) [ [ .This certainly has an intricate appearance, and wouldprove a most difficult cipher to any one not conversant with cryptography.But it will be observed that a, for example, is never representedby any other character than ), b never by any other character than(, and so on. Thus by the discovery, accidental or otherwise, of any oneletter, the party intercepting the epistle would gain a permanent and decidedadvantage and could apply his knowledge to all the instances in which thecharacter in question was employed throughout the cipher.
† ’ ; . ) [ ? 0 ‡ † [ ) ‘ — . ‡ & † [ ] : ) £ . ( . . ‘ * .
] — † £ . . * ) ' * — † ‘ ] ‡ ? ) [ † ] ) . ?
? ‘ † £ : ) ‘ * ] : ) ] [ . ’
In the cryptographs, on the other hand, which have been sent us by ourcorrespondent at Stonington, and which are identical in conformation withthe cipher resolved by Berryer, no such permanent advantage is to be obtained.
Let us refer to the second of these puzzles. Its key-phrase runs thus:
Surfeiter ire mono, fortiter in ret
Let us now place the alphabet beneath this phrase, letter beneath letter--
We here see that
a stands for ——————————— cIn this manner n stands for two letters, and e, o, and tforthree each, while i and r represent each as many as four. Thirteencharacters are made to perform the operations of the whole alphabet. Theresult of such a key-phrase upon the cipher, is to give it the appearanceof a mere medley of the letters e, o, t, r and i--the latter charactergreatly predominating, through the accident of being employed for letterswhich, themselves, are inordinately prevalent in most languages--we meaneandi.
d " " ——————————— m
e " " ——————————— z
f " " g, u and o
i " " ——————————— w
m " " e, i, s and k
n " " j and x
o " " ——————————— p
r " " h, q, v and y
s " " ——————————— a
t " " ——————————— t
u " " f, r, and b
v " " ——————————— d
A letter thus written being intercepted, and thekey-phrase unknown, the individual who should attempt to decipher it maybe imagined guessing, or otherwise attempting to convince himself, thata certain character (i, for example,) represented the letter e. Lookingthroughout the cryptograph for confirmation of this idea, he would meetwith nothing but a negation of it. He would see the character in situationswhere it could not possibly represent e. He might, for instance,be puzzled by four i's forming of themselves a single word, without theintervention of any other character; in which case, of course, they couldnot be all e's. It will be seen that the word wise mightbe thus constructed. We say this may be seen now, by us, in possessionof the key-phrase; but the question will, no doubt, occur, how, withoutthekey-phrase, and without cognizance of any single letter in the cipher,it would be possible for the interceptor of such a cryptograph to makeany thing of such a word as iiii?
But again. A key-phrase might easily be constructed,in which one character would represent seven, eight, or ten letters. Letus then imagine the word iiiiiiiiii presenting itself in a cryptographto an individual without the proper key-phrase; or, if this be asupposition somewhat too perplexing, let us suppose it occurring to theperson for whom the cipher is designed, and who has the key-phrase.What is he to do with such a word as iiiiiiiiii? In any of the ordinarybooks upon Algebra will be found a very concise formula (we havenot the necessary type for its insertion here) for ascertaining the numberof arrangements in which m letters may be placed, taken n ata time. But no doubt there are none of our readers ignorant of the innumerablecombinations which may be made from these ten i's. Yet, unless it occurotherwise bv accident, the correspondent receiving the cipher would haveto write down all these combinations before attaining the word intended;and even when he had written them, he would be inexpressibly perplexedin selecting the word designed from the vast number of other words arisingin the course of the permutation.
To obviate, therefore, the exceeding difficulty ofdeciphering this species of cryptograph, on the part of the possessorsof the key-phrase, and to confine the deep intricacy of the puzzle to thosefor whom the cipher was not designed, it becomes necessary that some ordershouldbe agreed upon by the parties corresponding--some order in reference towhich those characters are to be read which represent more than one letter--andthis order must be held in view by the writer of the cryptograph.It may be agreed, for example, that the f rat time an i occurs inthe cipher, it is to be understood as representing that character whichstands against the first i in the key-phrase; that the secondtimean i occurs it must be supposed to represent that letter which stands opposedto the second i in the key-phrase, &c. &c. Thus the locationof each cipherical letter must be considered in connexion with thecharacter itself, in order to determine its exact signification.
We say that some pre-concerted order of this
In these cursory observations we have by no meansattempted to exhaust the subject of Cryptography. With such object in view,a folio might be required. We have indeed mentioned only a few of the ordinarymodes of cipher. Even two thousand years
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