S O L V I N G C I P H E R S E C R E T S Edited by M. E . Ohaver

T R Y Y O U R W I T S O N T H E G R E A T C O D E S A N D C R Y P T O G R A M S I N

W H I C H M E N H A V E M A S K E D T H E I R M E S S A G E S O F L I F E A N D D E A T H

R E S P O N S E S to F L Y N N ' S cipher department are growing in number like the roll­ing snowball that doubles its weight at every turn. Readers are submitting their own ciphers as well as solving ours.

Unfortunately too many who submit them aren't ready to play fair with their audience. Their ciphers are too short. T h e y are made arbitrari ly hard.

B u t we are getting some worthy of passing on. And we are taking your hints to make our own ciphers a bit harder to solve. T r y

this one for instance.

i l H E remarkably ingenious methods of secret writing described in this article are usually attributed to the Russian Nihil ists, but as a matter of fact, their fun­

damental principle was the invention of the Greek historian, Polybius, who flourished in the second century B . C .

T h e several systems herewith described are al l based on the same cipher alphabet, commonly known as the checkerboard cipher, no doubt because of its resemblance to the board used in the game of checkers.

T h e basic idea of this alphabet, that of arranging the letters in a square so that any desired letter may be indicated by other characters placed along two sides of the .square, has been utilized by many cryp­tographers of various times. .A cipher by Bat is ta della P o r t a — 1 5 6 3 — a n d the famous ckiffre corre—cipher square—of Blaise de Vigenere—1586—may be cited.

A n d , besides, this ancient system contains the germ of many visual telegraphs, such as

the semaphore and wig-wag, in military use throughout the world. I t wi l l thus be seen that we are deeply indebted to our old friend Polybius; and that in this one achievement alone, he has erected an ever enduring monument to his ingenuity.

T h e alphabetical key is given below, pre­pared, of course, for the Engl ish instead of the Greek alphabet. Otherwise it differs from the original only in unimportant details.

1 2 3 4 5 UJ 1 A B C D E t

<3 2 F G H I J K

k 3 L M N 0 P <0 QC 4 Q R S T U ««. 5 V W X Y z

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S O L V I N G C I P H E R S E C R E T S 669

T h e person signaling the message accord­ing to the old Greek system, first held up on his left hand a number of torches, from 1 to s, to show the row of any desired letter. N e x t he held up on his right hand in a similar manner a number of torches which would show the position of the de­sired letter in that row.

F o r example, P would be telegraphed by first holding up 3 torches on the left, fol­lowed by 5 on the right; L , by 3 on the left and I on the right; and so on. I n sending a message, those torches not in use were con­cealed behind a wal l of about six feet in height.

A n d in receiving, a sort of dioptical in­strument consisting of two tubes was used, so adjusted that only the torches held up on the left could be seen through one tube, while those held up on the right would be visible through the other.

T h i s ancient telegraphic system lends it­self admirably for use as a cipher, in which the substitute for each letter consists of two figures: the first indicating the row, and the second the column of any desired letter, as in the subjoined example. Y o u wi l l note that, in the Engl ish key, both / and / are represented by the same number, 24.

Message: P L O T I S Cipher: 35 3 1 3 4 4 4 24 4 3

I t may seem a far c r y from the battle­fields of ancient Greece to the frozen wastes of modern Russ ia and Siberia, but the fact is that the Nihil ists , in search of effective methods of secret communication, chanced to come across this particular system.

A n d the Russian mind, naturally subtle and alert, lost no time in working out many clever applications of the checkerboard key.

Among these were several telegraph sys­tems not greatly differing from that of Polybius himself. T w o prisoners in sight of each other could communicate by hold­ing up the proper number of fingers in cor­rect sequence.

Or at night a candle was used; its light being alternately obscured and exposed un­t i l the desired information had been con­veyed in flashes from one prisoner to an­other.

Another important adaption of this sys­

tem is known as the prison telegraph. B y this method a prisoner could communicate with the inmate of an adjacent cell by tap­ping on the wall between them. T h e word Plot (35-31-34-44), for example, would be telegraphed thus: (P) three taps, pause, five taps, longer pause; (L) three taps, pause, one tap, longer pause; and so on.

T h i s system came to be used outside 0 ' Russia , and is said to be still practiced i n this country. E v e n a whispered conversa­tion in cells is forbidden by the American penal system, thus necessitating some secret mode of communication.

A t night a prison becomes a place of weird and subdued sounds, intermingled with stealthy rappings and tappings, which are, of course, heard by the watchful keep­ers, but cannot be accurately located. I n this manner plans for a break, or plots for crimes to be committed when the prisoners again are free, are relayed from cell to cell.

B u t to return to Russia, the Nihil ists went even further with their checkerboard key, and devised a cipher of masterly in­genuity of the double key variety. Ciphers of this type are so called because a message, after being enciphered by a first alphabetic key, is further obscured by an additional

D I S C O V E R E D 14 24 43 13 3 4 S I 15 42 I S 14

operation controlled by a secondary key, which usually consists of a secret key word known only to the correspondents.

So confident were the Nihil ists that this cipher was absolutely unbreakable, that they intrusted their gravest messages to it without the slightest fear that they would ever be read without the secret key word, even if they fell into the hands of the offi­cials of the Russian Cipher Bureau.

T h e complete method of operating this cipher is shown below.

I n line ( i ) is written the message to be enciphered, " Plot I s Discovered."

At ( 2 ) are entered the numerical substi­tutes for these letters, as found in the check­erboard key by the process already de­scribed.

At ( 3 ) the letters of the secret key word decided upon by the communicating parties are written under the letters of the message,

670 F L Y N N ' S

being repeated as many times as the length of the message ( i ) requires.

A t ( 4 ) the numerical equivalents of the letters of the secret key word are entered, being found in the checkerboard key i n exactly the same manner as were the num­bers of the original message in line ( 2 ) .

F i n a l l y at ( 5 ) the numbers in lines ( 2 ) and ( 4 ) are added, giving the numbers of the final cipher: 67-65-77-57-58, et cetera.

T h e cryptogram given below for solution has been enciphered by the Nihi l is t variable key cipher exactly as described in this art i­cle, wi th the exception that another key word than " Moscow " has been used. T o expect you to decipher this message with­out the secret key would perhaps be asking too much. B u t to hand you the key out­right would spoil the fun.

Therefore, as a sort of compromise, we

(1) P L O T 1 S D I S C O V E R E D ( 2 ) 35 3 1 3 4 44 24 43 i 4 24 4 3 i 3 3 4 S i i 5 42 i 5 i 4 ( 3 ) M o s c o w M o s c o w M o s c ( 4 ) 32 34 43 13 34 52 32 3 4 4 3 13 3 4 52 32 3 4 4 3 I 3

( 5 ) 67 65 77 57 95 46 58 86 26 68 103 47 76 58 27

I n practice the letters of the key word in line ( 3 ) may, of course, be omitted. A n d i n deciphering, the process as above de­scribed is merely reversed. T h e recipient writes under the numbers of the message the numbers of the secret key word.

H e then subtracts the latter from the for­mer, obtaining the simple numerical substi­tutes which can then be deciphered directly by the checkerboard key.

T h e Nihi l ist cipher in its more elemen­tary forms is a simple substitution cipher. T h a t is, it is a cipher in which a given letter of the alphabet is always represented by the same cipher character; and in which a given cipher character always represents the same letter of the alphabet. B u t the double k e y variety last described, is a poly alpha­betical substitution cipher.

I n other words, it is a cipher in which the concealment of the message is effected not by one, but by several different alpha­bets used in succession.

I n a cipher of this type a given letter of the alphabet may be represented by several different cipher substitutes; and conversely, a given cipher substitute may stand for several different letters of the alphabet. I n the above short il lustrative specimen, for example, the letter 0 is represented by both 77 and 68, and S by 95 and 86; while 58 is the substitute for both / and E.

wil l hide the key under the door mat b y causing you a little study in figuring it out. Here is the key in Nihi l ist variable key cipher, enciphered by means 0} itself as a key:

4 2 - 6 2 - 1 0 8 - 6 6 - 6 6 - 8 6

I f you think this leaves you out in the dark as much as ever, as an experiment just try enciphering any word you please by means of itself, and carefully study the results.

T h e cryptogram, a personal message to every cipher fan, follows:

4 5 - 5 2 - 1 0 8 - 6 7 - 7 8 - 9 5 - 4 5 - 6 2 - 8 5 - 7 6 - 4 8 - 7 6 - 3 5 -

4 2 - 6 7 - 7 5 - 8 7 - 7 8 - 6 5 - 6 5 - 7 6 - 7 5 - 4 4 - 7 5 - 7 3 - 7 3 - 7 8 -

7 7 - 7 7 - 5 8 - 5 4 - 5 5 - 8 7 - 7 7 - 5 6 - 5 8 - 5 4 - 5 5 - 7 7 - 5 7 - 6 4 -6 7 - 6 4 - 7 5 - 6 7 - 5 7 - 6 8 - 6 6 - 3 6 - 7 3 - 9 8 - 6 7 - 7 7 - 6 6 - 3 6 -4 6 - 6 8 - 5 7 - 7 7 - 7 7 - 6 3 - 6 5 - 7 5 - 7 7 - 5 6 - 6 7 - 6 4 - 4 5 - 6 9 -6 8 - 4 4 - 8 5 - 6 5 - 6 3 - 6 9 - 6 6 - 7 7 - 6 6 - 3 6 - 8 3 - 7 8 - 6 4 - 6 4 -5 8 - 5 4 - 4 5 - 6 9 - 4 4 - 8 4 - 7 7 - 6 3 - 7 5 - 8 8 - 4 7 - 4 8 - 5 6 - 4 5 -6 6 - 7 7 - 4 8 - 7 5 - 6 7 - 6 5 - 5 2 - 8 8 - 7 5 - 8 7 - 7 7 - 6 6 - 8 3 - 7 8 -77-56-7 7-66-75 - 9 8 - 5 6 - 4 8 - 6 8 - 3 6 - 8 5 - 1 0 6 - 6 7 -75-57-

I f you succeed in deciphering the above brain sprainer, send i n your solution to the editor of this department. A l l those re­ceived in time wil l be printed with the next article.

T h e correct solution of the Nihi l is t cipher, and a new article dealing with one of the most famous ciphers ever invented, w i l l appear in an early issue. W a t c h for further announcement.

Solution of the Augustus Cipher in Flynn's for February 2 1 T h e cipher in our last article was one of cipher by that letter next following it in

the simple substitution type, in which each the alphabet. T h e entire alphabet was thus letter of the message was represented in shifted forward one place, B being used for

S O L V I N G C I P H E R S E C R E T S 671

A, C for B, and so on unti l the message had original Augustus cipher was that he used been worked out. A A as the substitute for Z, as shown in his

T h e only exception to this rule in the complete cipher alphabet subjoined:

Message: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z Cipher: B C D E F G H I J K L M N O P Q R S T U V W X Y Z A A

T h e most frequent cipher letter as shown ceding i t in alphabetical order, and apply-by the frequency table was F, which oc- ing the same principle to the other letters curred fourteen times. Assuming that this of the cipher, the translation, as given here-was the substitute for E, the letter next pre- wi th , follows without any difficulty:

" T H E R E N E V E R W A S A T I M E W H E N M E N C O U L D A F F O R D T O T E L L T H E I R S E C R E T S T O T H E I R E N E M I E S . "

Correct solutions to the Augustus Cipher the following readers in time for publica-i n F L Y N N ' S for February 2 1 were sent in by tion in this issue:

John Amral l , Wolf Point, Mont. L e Roy Andei-son, Minneapolis,

Minn. Leo C. Augustine, Chicago. 111. Clyde Baughman, Tyrone. P a . E a r l W. Bowden. Harrington. R . 1. Violet Brooke, Haiulitou, Ont., Can. Leonard M. Bookman. Chicago, 111. George W. Burleson. Montreal. Can . Donald D. Burgess, Parsons. K a n . Charles E . Ballard, Brooklyn, N . Y . B a r r y B . Becker, Baltimore, Md. Louis Bachrach, Bronx, N . Y . W'illlam L . Buckl.ey, No. Weymouth,

•Mass. J . O. Cuthbert, Wllklnsburg, P a . Mrs. James A . Conway, Albu­

querque, N . M. John P. Crotty, J r . , Charleston,

Mass. W. A . Caudlll, Akron. Ohio. Milton Corbett, New Haven, Conn. Arthur L . Cadleux. Crookston. Minn. Mrs. Lorraine B . Common, Saginaw,

Mich. Evert Condes. Indianapolis. Ind. E a r l Dove, Alexandria, V a . John O. Dennis, Indianapolis, Ind. Edward J . Donovan, E a s t Boston,

Mass. IMrs. U . S. Denney, Clinton, Mo. H a r r y Drane, New York, N. Y . T . Donovan, Brooklyn. N . Y . Armaiid Degen, New York, N . T . Leonard Fischel , St. Louis. Mo. Sol Fksher, Philadelphia, P a . Wil l iam R . Frlske . Chicago. 111. F r a n k Y . Force. Ocean City, N . J , Francis A. Gauntt, Chicago. 111. Sargeant P. B . Gray, Fort Bliss ,

Tex. George H . Grover, Denver. Colo. Harris Glenn, Durant. Okla. R . M. Hilgert, FootvUle, Wise. Richard G . Horscroft, New York,

N . Y .

Mrs. L . B . Haldlmand, Leonia, N . J .

Mrs. H . C. Hepler, South Bend, Ind. Albert Hetteen, Malung. Minn. William Hoglund, Ironwood, Mich. Stanley H i l l , Effingham, 111. 0 . H . Howard. Toronto. Can. Harold Johnston, Waterloo, Iowa. John A . Kronberg, E a u Claire, Wis. J . O. K . . Louisville. K y . Andrew Kozlna, Mansfield, Ohio. Robert Kingsbury, Mount Airy ,

N . C. Oscar Krause, J r . , Racine. Wis . Ben Karpens, Baltimore, Md. Alex Lewis , Greenville. P a . George H . Liesenberg, New York,

N. y . Wilford Larson. Duluth, Minn. Austin Mlnette, Clear Lake . Iowa J . K . Manning, Morrlsonville, 111. Frankl in Miner. Winchester, Mass. E a r l Murphy, Fairmont, W. , V a . I'Yank Moucliet. Wallace, Idaho E . P . Mohr, Brooklyn. N . Y . Richard A. Miller, Charleston, .S. C. James F . McCarthy, Dorchester,

Mass. W'UUam T . McCaw, Cambridge.

IMass. Katherine Newham, Thomas, W .

V a . Charles F . Patterson, Mamaroneck,

N . Y . Isaac Rosenthal, New York, N . Y . George Rosenhloom, Brooklyn, N . Y . Edythe B . Gould, Troy, N . Y . Karl J . Ritchey. Poiitiac, Mich. Clarence Rolander, Topeka. K a n . Herbert L . Reed. Portsmouth, V a . Gertrude A . M. Reynolds, Woodslde,

N. Y . Haney Romhousek, Goshen, N . Y . T. J . Rowan, Thief River Fal l s ,

Minn. 1. M. Rothhart, New York, N. Y . B. Rapkln, New York, N . Y .

Notes and Queries

E r i c Rawcllfte, Argo, 111. Edward Roberts, Cleveland, Ohio Walter Sargeant, Cincinnati. Ohio H a r r y Shapiro. Detroit. Mich. Peter C. Schmidt. Wilkes Barre. P a . E a r l Walter Sutton, Cleveland. Ohio M. Eugene Snow, Roslindale, Mass. William Spring, New York. N. Y . Charles Schauwecker, Astoria, N . Y . H . B . Shea, New Haven, Conn. Jose Sanchez, Brownsville, Tex. Bob. TlhhetLs, Springfield, Ohio Pauline W. Tompkins, Philadelphia,

P a . Mrs. G. H . Thompson, Paris . Tex. Jack Thomas. Baltimore. Md. Evelyn Tohol, Maiden. Mass. Henry L . Verpaele. Moline. 111. George Welsh. Waterbury, Conn. Lester R . Wills, Center, Col. Sergeant Howard O. Whltt, Indiana,

P a . G. L . W . Will iams, Fort Lvon, Col. Mrs. W . T . Wheelock. Hannibal,

Mo. C. J . Westcott, Ossining. N. Y . Charles Wilson. Sunburst, Mont. Clifton Anderson, Manti, Utah E l m e r E . Brudos, Veolen, N . D. Walter 0 . Busby, J r . , Oaklawn,

R. I . Mrs. W. B. Curtis, Rockvllle Centre,

N . Y . Tlieo. S. Dylewsld, South Bend, Ind. V . T . French. Oak Park. I l l , Chas. Glasford, J r . , Council Bluffs,

Iowa. James F . Gilbert St. John, Can. Wil l iam Kearns. Brooklyn, N. Y . Williani Langis , New Bedford,

Mass. Arthur R . Mosler, J r . , New York,

N. Y . Martin L . Mlsenhelmer, Marshfield,

Ore. Lewis Wilder. Otsego. Mich. Joseph E . Phelps, Omaha, Neb.

W e are in receipt of an interesting let­ter from M r . F r a n k W . French, concerning a cipher of his own invention, which is ap­pended in fu l l :

D E A R S I R : Niles, Mich.

T h e following may be used if you wish—for publication with the understanding that I am not to explain how it is done until after patents are secured:

Message: J s Z i Z J V H B P Z Z P P F F M Z 2 L J s — R L

Key: T h e word " E u r e k a . " Translation: Repetition of the word

" E u r e k a . "

We are so sure it is " unpickahle " that we here give message, key, and translation, and defy any one to tell how to use the key to get the translation.

T h e system can he written or translated at the rate of from sixty to one hundred letters or figures per minute, by the ones for whom intended only. Yours truly,

F R A N K W . F R E N C H .

I n commenting on M r . French's cipher, it must be mentioned that, considered from the angle of ut i l i ty and not of structure, ciphers fall into two general classes.

672 F L Y N N ' S

T o the first class belong those ciphers which consist of a more or less simple key, knowledge of which by any unauthorized person would frustrate the secrecy of the cipher, and thus render it of no further value.

T h e Augustus Cipher described i n F L Y N N ' S for February 2 1 , the solution of which is in this issue, is one of this type. I t is easy to see how the field of usefulness of such ciphers is necessarily limited.

T h e second class incluaes those ciphers which are capable of many variations by means of a secondary key that can be changed at wi l l , and possession of which is required in order to read the cipher in the usual manner. T h e Nihilist variable key cipher i n this issue is such a cipher.

A l l ciphers intended for public use must obviously be of this second class, for the reason that it is possible for any interested person to obtain a copy of the cipher sys­tem, and become familiar with its use. T o illustrate just what is expected of such ciphers, let us consider army ciphers, which of al l others are expected to stand up satis­factorily under the most rigorous conditions.

F i r s t , it is taken for granted that the enemy is familiar with the cipher, either by capture during an engagement, through their espionage system, or otherwise.

I t is further considered that it is pos­sible for them to intercept five or six hun­dred messages per day during actual field operations.

A l l they lack is the secret key word. Under such conditions it is generally ac­cepted as true that any cipher of this kind can be solved if sufficient time is available.

F r o m this it wi l l be seen that even the best of such ciphers are not expected to be absolutely indecipherable. A l l that is re­quired is that any solutions wil l be so de­layed by difficulties encountered in de­ciphering, that any information discovered from the messages wi l l no longer be of value for the reason that such events as may have been mentioned wil l have already taken place.

T h a t a single message in such a cipher should resist al l attempts at solution is ad­mitted without any argument. B u t this does not mean that the cipher as a system

is unbrealvable. I t only means that when the material available in any one key is limited, occasional messages may be in­decipherable.

Y o u speak of having your cipher pat­ented. I t may be well to mention here that no device can be patented that does not involve some mechanical feature. I f your cipher can be arranged in the form of a cipher disk, a slide rule, or other mechani­cal device, it is patentable.

B u t if a printed description is all that your cipher wi l l require, the Patent Office wi l l only allow a copyright.

F i n a l l y , in as much as it is often desirable to send messages by wire, any cipher i n ­tended for general purposes should make use of only such characters as are found in the telegraph alphabets.

Also, in al l ciphers intended for tele­graphic transmission it is necessary to ar­range the cipher characters in groups of five, as this is the basis upon which tele­graph companies base their charge, each group of five characters being counted as one cipher word.

* * * T h e following letter is so good that we

must pass i t on to our readers:

Toronto, Ont., Canada. D E A R Sni:

I was keenly interested in the first of your new series of articles in F L Y N N ' S , " Solving Cipher Secrets. ' I never knew until I read your article that systems of secret writing were used as far back as the days of ancient Sparta. , I n fact, I should have said that ciphers were the invention of comparatively recent years.

I n my opinion F L Y N N ' S just needed a series of articles such as yours to " put it over." T h e detective fiction is first rate, but the cipher secrets add that little touch of variety which is necessary to a top notch magazine.

Hoping to see many more of your delightful articles in future issues, I am

Yours truly, C . H . H O W A R D .

M a n y thanks, M r . Howard, for your kind words of appreciation. J u s t such letters at yours wi l l induce us to expend stil l greatei efforts to please our ever-increasing circle of cipher fans. T e l l your friends about the new department, and be sure to watch foi our next article; it wi l l be of special interest, Wri te us often.

1 0 F W