• 

~ 

\ 

. ,, 

I r 

f I 

REF ID:A62846 

Fran the day that Ambassador Page sent his cablegram to President Wilson 

( 24 February 1917) quoting the English translation of' the Zirmnermann Telegram in 

the form in which it h$.d ' 1 ' been forwarded by Genaan Ambassador von Bernstortf' in 

j 

Washington to German Minister von Eckhardt in MeXico City, the entrance of the 

Uoited States into'the war as a belligerent on the side at the All~...;~~-~ ~~~ 1;t:oeL~..tAt...~~.l~~~-ft.~~,"tlA. /1--.d•.d:: .,,~'l'C£.~ -n~-"1>~-~-p~ ~'-'•...e...··r)~'1b~~ 

p.iier big black h~~ines the English text appeared in our newspapers~~ .. 

' I 

- ·-·-... wa ------, 

that the United States Congress declared war on Germany and the Central Powers. ~~......... __ .......... 

The date ~ ~ A,pr.ll,..~~:!· hor instance, here is the bold black 8-column lleallline 

in the New York Times of 1 March: 

GERMANY SEEKS ALLIANCE AGADTST U. S. 

ASKS JAPAN AND MEXICO TO JOIN BER; 

FULL TEXT OF BER PROPOSAL MADE PUBLIC. 

The New York World had a series of' headlines and subheads that extended halfway 

down the page, beginning with: 

MEXIOO AND JAPAN ASKED BY GEJl.WlY TO 

A'l'l'ACK U. S. IF IT ENrERED THE WAR; 

BERNSTORFF A LEADING FIGURE IN PLOT 

There followed nine fULl lines of' subheads to what was a most amazing and dramatic 

! story. ) 

. 

'• 

~ 

J 

I 

( 

~ 

• 

There l19re plenty of senators and representatives who disbelieved the story. 

It •s too fantastic; it was a British plot, unproved; Wilson was being taken in, etc., 

etc. But when Zimmel'ID8m1 himself' f'oo1"1shly acknowledged that he had indeed sent such 

-) 

a telegram, disbelief' changed quickly into vehe#ent anger. Surely war would now be 

declared on Gemany! 

Still, notwithstanding all the furor that the d:l:aclosure of the Zimmermann Telegram 

created in America, President Wilson still hesitated and it was not until more than a 

\_.JllDJlth later, and ai'ter several .American sh:ll!• "'"" sunk without -.ig on 18 llarch' 

17 

t"pproved for Release by NSA on 12-17-2013 pursuant to E. 0. 1352B 
REF ID:A62846 

In the War Department and in the Navy Department the pace set f'or preparing 

tor active war operations quickened. There was at the moment in neither ot those 

departments nor in tbe Army or in the Navy 8Zl7 organizations 'Whatever either f'or 

intercepting enemy ccmmnmications or f'or studying them. There was, it is ture, 

since the autumn of 1916 a very small group of self-trained cryptanalysts supported 

by a private citizen named Colonel Fabyan* who operated the Riverbank Laboratories 

at Geneva, Illinois. That organization maintained an unof'f'icial relationship with 

the authorities in Wa.Shington and received from time to time copies of cryptographic 

messages obtained by surreptitious means f'rom telegraph and cable offices in 

Washington. At that period in our history diplomatic relations with Mexico were 

in a sad state so that u. s. attention was concentrated southvard. Therefore 

practically all the messages sent to Riverbank were those of' the Mexican Government. 

Under my direction Riverbank was successful in solving· all or nearly all the Mexican 

cryptograms it was given usually retuming the so1utions to Washington very promptly. 

It was also successful with certain other cryptograms but I cannot deal with them • 

now because there just isn't time. Soon e.f'ter Will' was declared on Germany the 

Riverbank Laboratories established a schoo1 for training Army and Navy of'f'icers sent 

there to learn something about cryptology. 

You may like to know 'What we used for training ourselves for this unusual task, 

end later, 'What we used later on f'or training the student officers sent to Riverbank 

f'or crypto1ogic instruction. As regards our self-instruction training material, there 

w.sn 't much but among the very sparse literature in English there was a small book 

*Honorary title conferred by the Governor of' lllinois f'or Fabyan' s participation as 

a member of' the Peace Camnission that negotiated the Treaty of' Portsmouth, which 

followed the Russo-Japanes War in 19o6. 

18 
REF ID:A62846 

entitled Manual tor the Solution of Military Ciphers, 'Which had been prepared by 

a Captain Parker Hitt and printed by the Press of the Army Service Schools at 

Fort Leavenworth,, in 1916. The Signal Corps School was then one ot those schools,, 

and there a fev lectures were given by two or three officers who, when World War I 

broke out in August 1914,, took an interest in the subject of militar;y ciphers. They 

foresaw that sooner or later there would be a need tor knowledge and training in 

~litary cryptology. Capt. Hitt' s Manual, was then and still is a model of 

c~actness and practicality. Here is its title page. 

FIG. 00 

It ws the succinetness of the Manual that caused us much work and perspiration 

in our self-training. I later came to know and admire its author, wose photograph 

I show you. 

' 

There was one other item of training literature which we studied avidly too, 

a very small paq>blet entitled An Advanced Problem in Cryptogra.phy and its Solution, 

put out by the same Leavenworth Press in 1914. Here is its title page, and a 

photograph of its author then 1st Lieut. J. o. Mauborgne1 but later Chief Signal 

Officer of the Al'llfY. The advanced problem daal. t with bi? that p&q)blet was the 

Playf'a:l.r ciphers, about which I shall say something later. 

Retuming now to what our self-trained cryptanalytic group was able to do in 

a practical way in the training of others, there should be in NSA archives the 

many exercises and problems prepared at Riverbank for this purpose. They are still 

of much intereat historically. 

In Lecture II (Fig. 27) there is a picture of the last of the several classes 

sent by The Adjutant General of the Army to Riverbank for training. It should be 

noted that this instruction was conducted at Colonel Fabyen' s own expense as his 

19 
:. 

REF ID:A62846 

patriotic contribution, to the U. S. ·ua.r ettort. U,pon completion of the last 

training course I was commissioned first lieutenant and ordered imnediately to 

proceed to American General Headquarters in France where I became a member of the 

German Code and Cipher Solving Section of the General Staff', a designation that was 

abbreviated as G-21 A-61 GHQ-A.E .F. As the expanded designation implies, the 

operations were conducted 1n two principal sections, one devoted to vorking on 

German Army field ciphers, the other, to working on German Army field codes. There 

were other very small groups working on other material such as meteorologic messages, 

reports on direction-finding bearings, and what oge now call traf'f'ic 1 that is, the 

study of enemy messages in order to determine enemy order of battle from intelligence 

and analysis of D.F. bearing, of the direction, ebb and flow of enemy traffic and 

other data sent back from our radio direction-finding operations at or near our own 

intercept stations. 

In connection with the last-mentioned operations you will no doubt be interested 

to see what is one of the earliest, if not the very first chart in cryptologic 

history that shows the results of traf'f'ic analysis and its utility in deriving 

intelligence about enemy intentions fran a mere study of the ebb and now of enemy 

traffic. 

FIG. 00 

This particular chart was draw u;p fran data based solely upon the ebb and flow 

of messages in what llB.S called the .ADFGVX cipher*, a clever cryptosystem which was 

devised by German cryptographers and only used by German High Command communications, 

principally between and among the headquarters of divisions and army corps. 

*Initially this cipher em;ployed only the letters A, D1 F 1 G1 and x, for a matrix 

5 x 5; later, the letter was added, for a matrix of 6 x 6. 

20 
REF ID:A62846 

Theoretically it ws extremely secure because it canbined both a good substitution and 

I 

an excellent transposition principle in one and the same method without bet. ng too 

complicated for cipher clerks. Here is a diagram Yb.ich1 if' studied care:rul.ly1 will . ' 

give a clear understanding of its method of usage. If' you wish further details I 

suggest you consult documents available in the Training Literature Division o~ the NSA 

Office of Training. In this lecture there is only time to tell you that although 

individual Qr isolated messages in that system appeared at that time to be absolutely 

iJJilregne.ble against solution, a great many messages transmitted in the ADFGVX system 

were read by the Allies. You may be astonished by the foregoing statement and may 

desire same enlightenment here and nov on this point. Well, in b:ti-ef, the~ were 

in thoae days three different methods of' attacking the traffic in that cipher. under \.. 

the first method two or more messages w1 th identical plain-text beginning could be 

used to 'Im.cover the transposition as the first step. Once this had been done, 

the cryptanalyst had then to deal with a simple substitution in which, two letter 

combinations of the letters A, D, F, G, v, and X represented single plain-text 

letters. The messages were usually of' sufficient length for this purpose. under 

the second method, two or more messages with ide~tical plain-text endings could be 

used to 'Im.cover the transposition and this 'W.S easier even then 'in the case of messages 

with ,identical beginnings. You might think that cases of messages with identical I 

beginnings or endings would be rather rare, but the addiction to stereo-typic 

phraseology in the Ge:rman military mentality was then--and perhaps still is-so 

confizmed, that cases were almost invariably found in each day's traffic. This: 

is astonishing considering that the keys changed daily. This system first came 

into use on l March 19181 three weeks before the last and greatest spring offensive by 

21 
REF ID:A62846 

the German Army. Its appearance was almost coincident with that of other new 

codes and ciphers. The number of' messages in the .ADFGVX cipher varied f'rom about 

25 a day, when the system first went into use,, to as many as about 150 at the end 

of' two months. It took about a month to figure out a method of' solution, and this 

was done by a very able cryptanalyst named Capt. George Pa:invim. of' the French Cipher 

Bureau. 

The ADFGVX cipher was used quite extensively during May and June of' 1918 but . 

then the number of messages dropped very considerably. How many ditterent keys 

were solved by the Allied? Not many--10 in all,, that is, the keys for only 10 

different days were tcnmd. Yet,, because the traf'f'ic on those days was heavy about 

5~ of all messages sent in that cipher were read and a great deal of valuable 

intelligence was derived. On';one occasion solution was so rapid that an important 

Ge:rman operation disclosed by one message was completely frustrated. 

Although the .ADFGVX cipher came into use first on the Western Front,, it later 

began to be employed on the Eastern Front,, with keys that were f'irst changed every 

two days but later every three days. On 2 November 1918 the key for that and the 

next day was solved within a period of an hour and a half because two messages with 

identical endings were found. A 13-part message in that key gave the complete plan 

of' the German retreat tram Roumania. 

During the whole ,Je&r of' the lite of the ADFGVX cipher solution depended u;pon 

the three rather special cases I mentioned. No general so.J.ution for it was devised by 

the Allies despite a great deal of study. However,, members of' our own Signal 

Intelligencp Service, in 1933, and while still students undergoing instruction in 

22 
I 

• REF ID:A62846 

cryptanalysis, devised a general solution and proved its efficacy. .Pride in their 

achievement 'W8.S not diminished when, in the course of writing up and describing their 

method, a similar one was encomitered in a book by French General Givierge 

(Cours de Cr;yptographie), published in 1925. 

The .ADFGVX cipher was not the only one used by the German Army in World War I, 

and there will be time to mention oilly veey briefly two others. The first of these 

was a polyal.phabetic substitution cipher called the ''Wilhelm, " vhich used a cipher 

square vi.th a set ot 30 fairly lengthy keywords. The cipher square is shown in Fig. 00 

• 

and the set of keys as originally recovered is shown in Fig. oo. Just why the 

square contains only 22 rows instead of 26 is unknown. Certainly the rovs within 

the square are not random sequences for the letters within them manifest permuted 

arrangements in sets of vies; nor are the key sequences of random letters. I leave 

it to you to try to reconstruct the real square and the real keys. The latter 

problem should be relatively easy; as to the .former. I really don't know--! have 

never tried it myself but I suspect some systematic disarrangement, sanething typical 

of German cryptography. 

The other cipher to be mentioned is the double transposition, an example of which 

is shown in Fig. 00. The process consists in applying the same transposition key 

twice. Solution of the true double transposition usually depended upon ~inding two 

messages of identical length. No general solution was known to the Allies during the 

World War I. Occasionally an operator would apply only -the first transpostion and 

when this happended solution w.s easy. Then the key thus recovered could be used 

to decipher other messages which had been correctly enciphered by the double 

transposition. Again, students of the Signal Intelligence Service devised a general 

23 
REF ID:A62846 

solution for the double transposition cipher and during World War II were able to 

prove to our British Allies that such ciphers could be solved without having to f'ind 

two messages of identical length. Having demonstrated the weakness of the system 

even when properly employed, it was probably withdrawn f'ran usage by the British, but 

we were not told directly that this was done. I should add that I think the devising 

of a general solution for the true double transposition cipher represents a real 

landmark of progress in cryptanalysis without the aid of high-speed, electronic 

equipment. I do not doubt that with such equipment this cipher could hardly be 

thought to be safe for modem military secret communications. 

We came now to the code systems used by the belligerents in World war II. And 

first, let us di:f'ferentiate those used for diplanatic communications fran those used 

for military commtmications. What sorts did the German Foreign ~ice use'? We 

have noted that the British Black Chamber, "Roan 40 O.B." dealt with stupendous 

success on the code used for the transmission ot the Zimmermann Telegram. But 

that's only part of the story--the most important part remains to be told and 

unfortunately I cannot divulge that part yet. EJC.Cessive pride in German achievement, 

a wholely 1.mjustified confidence in their cryptosecur:l.ty, and a disdain for the prowess 

of ene:m,y cryptenal.ysts laid German diplomatic communications open to solution by the 

Allies to the point where there came a time when nothing the German Foreign Office 

was telling its representatives abroad by telegraph, cable or radio remained secret 

from the British. For those of you who would like to learn sane details, i I refer 

you to the following fine monograph on the subject by my late colleague Captain 

Charles J. Mendelsbhn: Studies in German Diplomatic Codes Employed During the World War, 

24 
------------------------------------------- - ---

REF ID:A62846 

Government Printing Office, 1937· This monograph is Confidentialj and copies are 

~available in the Office of Training, NSA. 

"At the time of America's entrance into the war German codes were an une:x;plored 

field in the United States, says Dr. Mendelsohn." About a year later w received 

f'rom the British a copy of' a partial reconstruction of' the German Code 13oli-O (about 

halt ot the vocabulary of' 19, 200 words and Boo of' the possibly 7, 600 proper names). 

This code and its variations of encipherment had been in use between the German 

Foreign ottice and the German Embassy in Washington up to the time of the rupture 

in relations, and our :riles contained a considerable number of messages, some of 

them of historical interest, which were now read v.f.th the aid of the code book." 

The vocabulary of the German dip:J_omatic codes contained 189 pages eontaining exactly 

100 words or e:x;pressions to the page, arranged in tw columns of 50 each accompained 

by numbers from 00 to 99. Here is a copy of a t;ypical page in Code 13o40. In each 

coluum the groups in the left-hand column, tor instance, 00-091 10-19, etc., to 

40-49; than 50-59, etc., were in blocks ot 10. The pages in the basic code were 

numbered at the top from 10 to 239 and f'rom this code several derivative codes were 

made by the use ot conversion tables. This enabled the original single basic doae 

to serve as the :l"ramewrk for codes tor several ditterent conmnmication nets. What 

the number of the basic code n.s is unknow, but we do lmow that from the derived 

code designated came codes 5950, 26oll.o, and others, derived merely by means ot tables 

tor converting the page numbers in the basic code into different page numbers in the 

derived code. These conversions wre systematic, in blocks of tours. Thus, for 

exaq>le, pages 15-18 in code 13o40 became paaes 65-68 in code 5950, etc. Then there 

were tables tor converting line numbers from one code into different line numbers in 

25 
REF ID:A62846 

another version of the basic code, and this was done in blocks of 10. For example, 

the fifth block (penultinate figure 4) became the first (penultimate figure o), 

and the 1st, 2nd, 3rd, and 4th blocks were moved dow one place. The other five 

blocks (on the right-hand side of the page) were :aearranged in the same manner. 

It is obvious that codes derived in such a manner f'rom a basic code can by no 

means be considered as being different codes. They "Were all relatively minor 

equivalents of one another. Also to be mentioned is the fact that in certain cases 

3-dig:Lt numbers were added to or subtracted from the code numbers of a message and 

' that in practically every case it w.s not difficult to determine the"'additive .. or 

A.btraetive. 

In none of the cases or codes mentioned thus far was there one that could 

at least be considered to be a randomized," hatted," or true two-part code, since 

the same book served for both encoding and decoding. Some of these, besides the 

ones already mentioned {13o40 and 5950) were designated b~ indicators, such as 

12444, 1357, 18470, 1777, 2815, 4565, 5717, 44499, 58585, 2310, 98989, 1111, 80574; 

there were others besides these. It is my belief that conversion tables were not 

used by the code clerks but by the compiling authorities in Beolin. In other words, 

the various versions of the basic code were not actually printed as separate books 

but that the orig:lnal page number on each page was altered by hand, the original 

number being crossed out and witten either at the top or the bottom of the page, 

perhaps in both places. Similarly, the block numbers were probably changed bybmd. 

In both cases the alterations were in accordance with some system, the idea of 

randomicity seems foreign to the German mentality, and I am sure that if' randomicity 

were a desideratum. they would figure out a system therefor. Bowver, the German Foreign 

26 
REF ID:A62846 

Of'f'ice later on did compile and use true two-part, truly randomized codes of 101 000 

grou;ps num.bered from 0000 to 9999. One such code l1ad as Jits indicator the number 7500 • 

.And that there were several others like it I have no'.doubt. 

When one reviews Dr. Mendelsolm's monograph one becomes overwhelmed by the 

multiplicity of the codes and va.Hants thereof! used by the German Foreign Of'f'ice. Many 

were basic codes but many were derivatives,, or superencipherments thereof'. It is even 

hard to ascerta:ln the exact number of different methods. Yet a great deal of' the 

traffic in these codes was read. Considering the rather small num.ber of' persons 

on the cryptanalytic staff' of G-2 in Wa.Shington and its hanologous organization in 

London,, in the British Black Chamber,, one can only be astonished by the great 

achievements of' the efforts of these two collaborating organizations during World 

War I. 

So much for German diplanatic secret communications. What about German military 

crypto-camnunications'l In this area it is necessary to mention a situation which is 

somewhat unique. When World War I commenced the German Army was very poorly prepared 

to meet the requirements for secure comnnmications. It seems that u;p until the 

Battle of the Marne in 1914 several German Anny radio stations went into the field 

without any provision having been made or even foreseen tor the need f'or speedy 

and secure crypto-communications. ::ivumerous complaints ~re registered by German 

commanders concern.ins extensive loss of time occasioned by the t:ar too complicated 

methods officially authorized for use and the cousequent necessity for sending messages 

in the clear. Not only did this reveal intelligence of importance to their opponents 

but what is equally important the practice pennitted the British and the French to 

became thoroughly familiar Yi.th the German telegraphic procedures, methods or 

27 
REF ID:A62846 

expression, terminology and style, and these items became ot great 1mport;ance in 

cryptanalysis when German cryptosystems improved. For the German Army learned by hard 

experience something about is shortcomings in this area of wa.rf'are and began to 

improve to the point where we must credit the Germans with being the initiators of 

most ot the nev and very important developments in field military cryptography. In 

fact, the developments and iJ:ri>rovements began not longer after the Battle of the MamJt 

and continued steadily until the end of' the war. When on ll November 1918 the armistice 

ended active operations, German military cryptography had attained a remarkably high 

state of efficiency. The astonishing f'act, however, is that, although very 

proficient in cryptographic inventions, they were apparently quite deficient in 

the science and practice of cryptanalysis. In all the years· since the end of 

World War I no books or articles telling of German success with A11ied tra.tf'ic during 

that war have appeared same f'or one very brief' a.:rticle by a not very bright German 

C?r.YPtanal.yst. One could of course assume that they kept their successes very well 

hidden but the German archives taken at the end of World War II contain nothing 

significant in regard to cryptanalysis during World War I although a great deal of 

1mportant inf'ol'DlB.tion in this field during World War II was f01.md. A detailed account 

of' the cryptologic war between the Allied and German forces in World War II would 

require scores of' volumes,, but there is one source ot inf'omation wich I can highly 

recommend to those ot you who "WOuld like to lmow more details of the ceyptologic 

warfare between the belligerents in World War I. That source is a book wr:L tten and 

p"&blished in Stockham in 1931 by a S-wedish cryptanalyst, Yves Gylden, under the title 

Chif'f'erb;yraemas Insatser I Varldskriget Till Lands,, a translation of which, vi.th sane 

28 
REF ID:A62846 

comments of my own in the form of footnotes, you will find on tile in the Office ot 

Training, NBA, under the title The Contribution of the Cryptographic Bureaus in the 

World War, Government Printing Office, 1936. 

In this lecture, howver, we are principally concerned with German military 

cryptography duHng World War I, end I have already told you sanething about the 

cipher systems that were used. There rem.in to be discussed the field codes. It 

was the German Army which first proved that the old idea tbat codebooks were 

impractical for use in the combat zone for tactical communications was wrcmg. They 

had two different types of field cod.es, one which the Germans called the SCBLUESSEL HEFT 

or "key" but which we called the "three number code"; the other the "three-letter 

code". The former was a s-.11 standardized code vi th a vocabulary of frequently 

used words and expressions, digits, letters and syllables totally 11 000 items for 

which the code equivalents were 3-digi t numbers. A cipher was applied only to the 

first two digits of code numbers and this cipher consisted of a 10 x 10 m.trix for 

~ ~bers from 00 to 99. Tbe last digit of a code sro\Z.P rem.ined unenciphered. 

Each division compiled and issued its own table, which was in two parts, one :fbr 

encipherment the other for decipherment. The three-number code was intended for 

use in all forms of' cc:mmunication within or to and from a 3-kilometer front-line 

danger zone. Although this code was compiled by the end of January 1918 it was not put into 

use until the opening day of the J.ast and greatest German offensive, 10 March J.918. 

'!'be nature of the new code was ascertained and a few gro\Z,Ps in it were solved the 

very same day because an operator who was unable to translate a message in the new 

code requested and received repetition 1n the old code, the three-J.etter code, and 

~ J.etter had been solved to an extent which -.de it possible to identity homologous 
REF ID:A62846 

code groups 1D both messages. The three-nmber proved rather eas7 to solve on a 

dail.J' basis and much useful intelligence was obtained thereby. 

The solution of the three-letter code, however, PJ"Oftd"'much more difficult. ID 

the first place 1 it bad a much larger vocabular;y 1 vi th nulls and JllBZl7 variants for 

trequentl.J'-used words and numbers; in the second place and what constituted the real 

stumbling block to solution was the tact tbat it was a true two-part randODllled or 

"batted" code; and 1D the third place, each sector of the front used a different edition 

of the code, 00 tbat traffic mt only had to be identified as to the sector to which 

it belonged but also it was not possible to combine all the messages tor the purpose 

of building up frequencies of usage of code groups. Working Vi th the sparse amount 

of traffic within a quiet sector of the front and 1irJ1!lg to solve a .tew messages in 

the code was realq a pa1Dtull7 slow, veey difficult and generall.J' frustrating 

experience. On my reporting for dut7 Colonel FraDlt Moorman, wbo was Chief of the 

wbole unit and whose photograph I show you here, asked me vbe:llber I wished to be 

assigned to the cipher section or to the code section. Having bad considerable experience 

with the solution of the former types of cryptos1'Stems but none with the latter, and 

be.:bJg desirous of gaining such experience I asked to be assigned to the code solving 

unit. I gained the experience I wanted and needed to broaden knowledge and practice 

in cryptol087 but little did I realize what a painful and frustrating period of 

learnillg and traiDi.JJg I bad undertaken. Still, I have :never regretted the choice 

l made; 1D tact, it turned out to be a very wise and useful one. If mJ¥ of you 

would like to read about my experience in this area, let me refer you to my 

monograph entitled Field Codes Used by the Gel'IBD Army durillg the World War, copies 

of which are on file 1D the Office of' Training, l'ISA.. I ~ quote a :few paragraphs 

from my "estimte of' the three-letter code" as it appears on page 65 of that momgraph: 

30 
REF ID:A62846 

What sort of ceyptosyatems did tbe French Artq use? First, as tor ciphers, they 

put much trust in transposition methods and here is an example ot one type: 

FIG. 00 

As for codes, like the Gel'EllS the7 used a small, front-line booklet called 

a "Carnet Reduit", or an "Abbreviated Codebook". Various sectors of the troDt bad 

different editions and I will. show a picture of one of them. Then, 1D addition, there 

was a much more extensive code wbich was not onl7 a two-part, ralJdomized book, of 

10,000 four-digit code groups but a superenciphermen.t was applied to the code messages 

when tn.nsmi tted b7 radio or b7 "TPS•, tba t is, "telegraphic par sol", or earth· 

telegraphy. Here is one of the tables used tor enciphering (and deciphering) the 

code groups: 

FIG. 00 

Am here is the example of superencipherment given 1D the code in my collection: 

FIG. 00 

You will notice that the enciphering process breaks up the 4-digit groups 

1D a rather clever llBmler b7 enciphering the first digit of the first code group 

separately'; the second and third digits of the first group &1'e enciphered as a pair; 

then the last digit of the first group and the first digit of the second code group 

are enciphered as a pair, and so on. Tb.is procedure suceeds 1D break:lllg up the digital 

code groups 1D such a JllBDller as to reduce veey greatJ.7 the frequenc7 of repetition of 

4-digi t groups repreaeatiDg words, nmbers 1 phrases, etc., of very- COlllllOD occurrence 

in militaey messages. M1' appraisal of this French Arrq crn>tosystems is tbat 

theoretically at least, it certaiDly was the most secure of all the s79tems used by 

the belligerents but I don't know how much usage was made of it. I venture the 

op1D1on that it was not used often, or successfull7, with the superenciphering method 

provided for the basic code. 

31 
REF ID:A62846 

Now how about the cr.n>tosystems used by the British Army! First, they used 

the Pl.ayf'air Cipher, a system of digraphic substitution considered in those days 

to be good enough for unimportant messages in the canbat zOn.e. Bu.t toda;y, of course, 

1 ts security is kDowD to be so low as to be unvortby of pl.acing any reliance in it. 

The British e.lso used a field code. It contained many COlllllOD militar.Y e:xpressions 

and sentences, grouped under various headings or categories, and of course, a very 

small vocabulaey of trequentl;y-used words, numbers, punctusl1on, etc. It was always 

used with superencipherment, tbe nature of which was not disc1osed even to their 

Allies, so I unf'ortunatel;y am not in a position to describe it. I don't even have 

a caw of their code--onl.y a tJ:pewri tten transcript which was furnished WI 

quite reluctantl;y and I will show a tJpical. page thereof. 

FIG. 00 

What about tbe cryptosystems used by the ItaliaD. Arrq in World War n The 

genera1 level of cryptologic work during tbat period was quite low in character, 

a f'act which is all the more remarkable when we consider that tbe birthplace of 

modern crypto1ogy was in ItaJ.;y several centuries bell'ore tais period. There appears 

to have been in Italy a far greater knowledge of cryptologic techniques in the 15th 

and 16;1:ib Centuries than in the 19th, paradmcie&l. as this m7 seem to us toda.7 • 

Perbaps this can be considered as one of the consequences of a policy of secrecy 

which not only makes filing away in dusty archiVea records of CJ"1Ptanalytic successes 

a desideratum but also binders or absolutely" prevents those wb.o might have been 

bol'Jl vi th what it takes to develop a f'lair for cryptologic work f'l'om profi tting 

f'l'om the progress of predecessors wb.o have been successful in such work. Should 

we be astonished to learn, therefor, that when Italy entered into World War I the 

Italian Arrq put its trust in a very aimpl.e variation of the ancient Vigenere cipher, 

32 
REF ID:A62846 

a system called the "cif'rario militaire taseabile" or the "pocket military cipher"? 

It, as well as aevera1 others devised b7 the same Italian "expert", were solved 

very eas:ll.7 by the Austrian ceyptanal.ysts during the war. ihe Italian ArllJ7 also 

used cod.es, no doubt, but since encipberment of such codes consisted 111 adding or 

subtracting a number from the page number on which a given code group appeared, the 

security of such systems was quite illusory. As late as 111 1927 the same Italian 

"expert" azmounced bis invention of an absolutel7 indecipherable cipher system 

which,. GYlden BIQ'B (page 23) "still further deD10D.Strates the astonisbiDg lack of 

cmprehenaion of modern ceyptaZJalytic methods on bis part." 

What. about RussiaD cryptologic work in World War IT So f'ar as Russian 

ceyptograpbic work is concerned. we know tbat there was during Czaristic days an 

apparently' veil organized and ef:f'ective bureau for constructing and compiling 

diplomatic codes and ciphers, organized b7 a Russian named SaviDsq, formerly' 

Russian Minister to Stockholm. He had all codes and cipher 111 use u;p to then 

improved, introduced strict regul.atiODB for their use, and kept close watch over 

the service. B'e also was head of a cryptaDalytic activit7 and it is known tbat 

Turkish., British., Austrian and swedisb diplom.tic messages were solved. After the 

Bolshevik revolution of 1916 some of the Russian ceypta.nal.yata miiaged to escape from 

their homeland and I had the pleasure of meeting and talking with one of the best of 

them during bis service in the black chamber of one of our Allies 111 World War II. 

He vore with great pride on the 1.llde:x finger of his right haDl a ring in whtch 

was mounted a beautiful large rub7, the ring haviJJg been presented him by the 

last Czar in recognition of bis ceyptanal.ytic successes while 111 his service. 

Dlt the story is al together different as regards ceyptolog in the Russian Ar11J7. 

33 
REF ID:A62846 

The Military Ceyptographic Service was poorl7 organized and, besides, it had adopted 

a ceyptographic system which proved to be too complicated for the ignorant and poorly 

trained Russian cipher and radio operators to use when it was placed into effect toward 

the end of 1914. Here is an example of that cipher, which bas an enciphering and a 

deciphering tab1e: 

FIG. 00 

In the enciphering table the letters of the Russian alphabet (33 in all) appear 

in the top line; the 2-digit groups in random order within the 8 rows below are their 

cipher equivalents and these rows therefore constitute a set of 8 cipher alphabets 

preceded by key numbers from 1 to 8 in random order, also subJect to change. Indicators 

were used to indicate how ma.DY letters were enciphered consecutiveq in each alphabet, 

the indicator consisting of one of the digits from 1 to 9 repeated five times. The 

alphabets were then used in ke;r-number sequence enciphering the first set of' letters 

(5, 7, etc., according to the indicator) b7 alphabet 1, tbe next set b7 alphabet 2, 

and so on. Aft.er the 8th set of letters, which was enciphered b;r cipher alphabet 8, 

return is DBde to cipher alphabet 1, repeating tbe sequence in this marmer Wltil the 

entire message bad been enciphered. In enciphering a long message the cipber operator 

could chal:lge the number of letwra enciphered consecutively by inserting another indicator 

repeated five times and then continuing with the ne:xt alphabet in the sequence of 

alphabets. The cipher text was then sent 1D 5-digit groups. The use of the deciphering J 

table bardl;r requires explanation but a question may be in order: Why the aversion 

to the use of zero and to the use of double digits such as 11, 221 33, etc'l This 

remins a puzzle to me. 

I have told you that this cipher system proved too difficult to use, so difficult 

that messages had to be repeated over am over, with great loss of time. It is well 
REF ID:A62846 

known that the Russians lost the Battle of Tmmenberg in the autumn of 1914 was 

largely because of taul t)r comanmications. Poor cryptography or failure to use 

even simple ciphers properly on the field of battle, and not brilliant strategy on 

the part of' the enemy, was the cause of' Russia's defeat in that and in subsequent 

battles. '!he contents of' Russian cODDDunications became known to the German and 

Austrian High COD1DN1ds within a f'ew hours after transmission by radio. Tbe 

disposition and movements of' Russian troops, and Russian strategic plans were no 

secrets to the enemy. The detailed and absolutelymliable information obtained by 

intercepting and reading the Russian communications made it very easy f'or the German 

and Austrian commanders not only to take proper counter-measures to prevent the 

execution of Russian plans, but also to launch attacks on the weakest parts of' the 

Russian front. Although the Russian ciphers were really DO~ complicated their cipher 

clerks and radio operators found themselves unable to exchange messages with accuracy 

and speed. As a matter of' tact they were so inept that not only were their cipher 

messages easily solved but also they made so JIBD1' errors that the intended recipients 

themselves bad considerable difficulty in deciphering the messages even With the 

correct keys. ID some cases this led to the use of plain language, so 'that the 

German and Austrian forces did mt even have to do ~ing but interce::pt the messages 

and translate the Russian. To send out dispositions impending movements, iJllllediate 

and long-range plans iD plain language was, of course, one cardinal error. Another 

was to encipher only words and phrases deemed the important ones, leaving the rest 

iD clear. Another cardinal error,, made when a cipher was superseded, was to read 

a message to a unit that had mt yet received the new key and then repeat the identical 

message iD the old one. I suppose the Russians cODDDitted every error in the catalog 

of' cryptographic criminology. No wcmder they lost the Battle of Tannenber.g, which 

35 
REF ID:A62846 

one military critic said was not a battle but a •ssacre, because the Russians lost 

1001 000 men in the B·da.7 engagement, on the lastlda.7 of which the Russian cOJID'INlderin-chief cOD1Ditted suicdde. Three weeks later another high Russian cODIDBDder followed 

suit and the Russian Arm:! began to fall apart, completely disorganized Without leadership 

or plans. Russia..i tself began to go down in ruins when its Arm:!, Navy and Government 

failed so completely, and this made way for the birth of the October revolution, 

ushering in a regime that was too weak to put things together again and to hold them 

together. The remanta picked up by a small band of fanatics with military and 

administrative ability, with treachery, violence and cunning, welded together what has 

DOV become a mighty adversary of the Western World, tbe USSR. 

I have left to be treated last in this lecture the Cl'1Ptosystems used by the 

American Expeditionary Forces m Europe during our participation in World War I. 

When the first contingents of the AEF arrived in France in the sUDBDer of 1917 1 

there wen available fir secret c011111UDications within the AEF but three authorized 

means. The first was that extensive code for administrative telegraphic correspondence 

the 1915 edition of the War Department Telegraph Code about which I've already told 

you something. Al.tbough it was fairl.y well adapted tor tbat t;ype of commmication, 

it was not at all suitable for rapid and efficient strategic or tactical colllllUDications 

in the field, nor was it sate to use without a clumsy superencipherment. The second 

cr;yptosystem available was tbat known as the repe11;t1Dg-key cipher, vb.itch used the 

Signal Corps Cipher Disk, the basic principles of which were described as far be.ck 

as about the year 1500. The third system available was the Playfair Cipher, which 

had been trankly copied from the British,, who had used it as a 1'11tld cipher for many 
REF ID:A62846 

years before World War I and continued to use it. ID addition to these authorized 

means there were :from time to time current in the AEF apparentl.7 severa1--bow lllS.IJ1"1 

no one knovs--unautborized, locally-improvised "codes" of varying degrees of security, 

mostl.7 nil. I show one of these 1n Fig. oo, and v1ll let you assess its security 

yourself. 

FIG. 00 

Seen in retrospect, when the AEF was first organized it was certaiDJ.y unprepared 

for band.ling secret c01111DUDications in the field; but it is certain that it was no,, 

more unprepared iD this respect then was BD1' of the other belligerents upon their 

respective entries into World War I, as I've indicated previausl.J' in this lecture. 

This is rather strange because never before in the history of warfare had crn>tol08J 

played so important a role. When measured by today's standards it must be said 

' 

that not only was the AIF unprepared as to secret cODlllUDication means and metbods 

and as to Cr.YJ>ta.Dalysis, but for a limited time it seemed almost hopeless that the 

AEF could catch up with the times, because their British and French Allies were at 

first mat reluctant to disclose much of their hard-earned information about these 

vital matters. 

Nevertheless, and despite so inauspicious a cormnencement, by the time of the 

Armistice, in November 1918, not only had the AEF caught up with their allies but they 

bad surpassed them 1n the preparation of sound codes, as may be gathered :from the tact. 

that their allies had by then decided to adopt the AEF system of field codes and 

methods for their preparation, printing, distribution, and usage. 

Just as the invention of' Morse wire telegraphy- had a remarkable effect upon 

military CClllllUJlications during the .American Civil Wa,r, as related in the preceding lecture, 

37 
REF ID:A62846 

so the invention of radio also played a very important role 1D field conmnmications 

during World War II. Now, altboggh it can bardl.7 be said that all cOllllll8Dders from 

the very earliest cla.y'8 of the use of radio 1D military conmunications acuteq recognized 

' 

one of the most iJqportant disadvantages of radio--nameq, the fact tbat radio signals 

ma.7 be more or less easiq intercepted 'b7 the ene:my--it was not lcmg before the 

consequences of a complete disregard of this obvious fact iJqpressed themselves upon 

most c()D!DBnders, with the result that the transmission of plain language became 

the exception rather than the rule. This gave the most momentous stimulus to 

the development and increased use of cryptoloa that this service bad ever experienced. 

Let us review some of the accomplishments of the Code Canpilation Service 

under the Signal Corps, AEF. It was organized in January 1918, and consisted ot one 

captain, three lieutenants and one" enlisted mrm. Until th.is service was organized, 

that is, fraD the sUDDer ot 1.917 until the end of that year the AEF had nothing tor 

cryptoconmnmications except those three iDadequate means, that I've mentioned. 

When it had been determined that field codes were needed little time was lost in 

getting on with the job that had to be done. Since I had no part 1D this effort I 

can sa7, without daDger ot being misunderstood as to motives, that the Code Compilation 

Service executed the most remarkable job 1D the history of military cryptography" up 

to the time of World War II. 

Tbe first work entrusted to it was the canpilation ot "Trench Code", ot which 

1000 copies were prillted, together with what were called "distortion tables". These 

were simple monoalpbabets for encipher:l.Dg the 2-letter groups of the code. I show 

a picture of a page of' this code and of one of the "distortion tables". 

FIG. 00 

(p. 132) 

FIG. 00 

(p. 142) 
REF ID:A62846 

Tbe da.Dger of capture of these codes was recognized as being such that the books 

were not issued below battalions. Bence, too meet the needs of the front line, a much 

smaller book was prepared and printed, called the "Frcmt Line Code". Distortion tables, 

30 ot them in all, were issued to accompany this code of which an edition of 31 000 copies 

was printed--but not distributed, because a study of its security showed defects. 

AEF cryptographers were grouping 1n the dark, vi th little or .no help fran" allies and 

with persom:ael inexperienced 1n cr;ypta.nalyais. FinaJ.ly, the light broke throMb: 

tbe Code Compilation Service began to see the advantages of the German 3-letter l'B.Ddomized 

2-part code known as tbe Satzbuch. I've tol.d you about this code and what the AEF 

learned aboUt its advantages. Here, then, was the origin of the AEF real Trench Codes--

copying from the experience of German code compilation and then goiDg them cme'better. 

The first code of the new series, known as the "Potomac Code", the first of tbe 

so-called "American River series," appeared on 24 June 1918, in an edition of 21 000 

copies. It ccmtained approximtely 11 700 words and phrases and, as the official report 

so succinctly states, "was DBde up with a coding and decoding section in order to 

reduce the work of the operators at the front." The desigaation "two-part" or 

"randomized," or even "hatted" code was still UDkDown--but the principle was there 

nonetheless.;- Let us see what the official report goes on to say on this point; let 

us listen to some sound commense sense: 

"The main point of' difference from other Arlq codes lay in the 

principle of reprinting these books at frequent intervals and dependiDg 

largely upon the rapidity of the reissuance for the secrecy of the codes. 

'!his method did away With the double work at the front of ciphering and 

deciphering [SicJ], and put the burden of work upon general headquarters, 

where it preperly bel.onged. 'Under this system one issue of codes could 

be distributed down to regiments; another issue held at Ariq Headquarters; 

and a third issue held at General Headquarters. As a matter of record this 

first book, tbe Potomac, was captured )1' the enem;y cm July 20, Just one month 

after issuance, but within two days, it had been replaced throughout the 

entire Artq in the field." 

39 
REF ID:A62846, 

!be repla.cement code was the Suwanee, tbe next in the River Series, followed 

by the Wabash, AlleghelJ1'1 and the Hudson, all for the American First Aztq. In 

Oct.ober 1918 a departure in pl.an was made and different codes were issued simultaneously 

t.o tbe First and Second Armies. This was done in order not t.o Jeopardize urmecessaril;y 

the life of' the codes by putting in the field at one time 5,000 and 6,ooo copies 

of B.rJ7 cmne issue. 'l'.b.us the Champlain, the first of' what came t.o be called the "lake 

Series" f'or the Second Aztq was issued with the Colorado of' tbe "River Series" for 

the First Army; these were followed b;y the HUl'OD and the Osage, the Seneca and the 

Niagara, in editions of' 2,500 each. 

In addition to the foregoing series of' codes were certain others that should 

be mentioned, as fer example, a short code of 2-letter code groups t.o be used b;y 

front line troo)NI as an emergency- code; a short code list for reporting casualties; 

a telephone code for disguising the names of' comanding officers and their units, 

and so on. Bu.t there was in addition t.o all the foregoing one large code that must 

be mentioned, a code t.o meet tbe requirements f'or secure transmission of' message 

among the higher colllllELllds in the field and between these and GHQ. This was a task 

of considerable magnitude and required several months stud;y of' messages, confidential 

papers concerning organization, replacement, operations, and of military documents of' 

all sorts. Tbe code was to be known as the AEF Staff Code. In May 1918, the mnuscript 

of' this code was sent to press and the printing job was done in one month b;y the printing 

facilities of the AEF Mjutant General. Considering that the cdde contained approxim.tel;y 

301 000 words and phrases, accompanied b;y code groups consisting of 5-figure graips 

and 4-letter groups, the task completed represents a remarkable achievement by a field 

40 
REF ID:A62846 

i 

printing organization and I believe that this was the largest and most comprehensive 

codebook ever compiled and printed by an army in the field. More then 50, 000 

telegraphic caabinations were sent in tests in order to cast out combinations liable to 

error in transmis.sion. One thousand copies of this code were printed and bound.. With 

this code as a superencipherment system there were issued from time to time 

"distortion tables." There re•ins only to be said that the war was over before this 

code could be given a good work-out, but I have no doubt that during the few months 

it was in effect it served a very aaetul purpose. Moreover, the excellent vocabulary 

was later used as a skeleton for a new War Department Telegraph Code to replace the 

edition of 1915. 

One more code reEins to be mentioned: a "Radio Service Code," the first of its 

kind in the American Army. This was prepared. in October, to be used instead of a 

French code of similar nature. F1Dally1 anticipating the possible' requirement for 

codes for use by the Army of Occupation, a series of three small codes, identical in 

format with the war-time trench codes of the: river and lake series, was prepared, and 

printed. They were naned simply Field Codes No. l, 2 and 3 but were never issued 

because there turned out to be no need f'or them in the quietude in Germany after the 

Army of Occupation marched into former enemy, but now very frielJdly territory. 

I will brilJg this lecture to a close now by referring those of you who might 

wish to learn more about the successes and exploits of the cryptographic organization 

of the AEFiin World War I to my monogr~ph enti tl.ed American Army Field Codes in the 

.American Expeditionary Forces during the First World War, Government Printing Office, 194-2. 

Copies are on file in the Office of Training. In that monograph you will find m.ny details 

of interest which I have had to omit in this talk, together vi th many photographs of the 

codes and ciphers produced and used not only by the AEF but also by our allies and enemies 

during that conflict. 

41