I 

----·------- ------ -

AS-14 

AS•2J 

AS-So 

AS-22 

REF ______ ID:A71920 ............ 

HIE~l !Hiiji» lJ ~fW 

Aug J 1949 ~ 32-( ) 11Cor.imunication Intelli'Jence and 

Communication Security" 

Capt. Campbel.!. Ext Jl7 

1. Inclosed herewith in first draft of Chapter I of the proposed .FtvJ. 32-( ), 

Communication Intelligence and Communication Security," currently being prepared 

by Lt. F. A. Geb, Jr., at Fort Monroe, virginia. 

2. It has not been indicated to AS-22 whether paragraph 2 has berm omitted 

purpose, will be inserted later, or whether this is an error in number.i.ng. 

J. It is requested that this chapter be reviewed and that limited comments 

on the writer's .!EJU:.2!~ ~ ~ suqject be forwarded to AS-22 by 10 August 1949. 

4. It is to be pointed out that when completed, the entire manual will be 

coordinated thoroughly within the Agency. 

l Incl (in trip) 

Drai't, subj as above 

CHARLES H. HISER 

Lt. Colonel, Signal Corps 

Acting Deputy Chief 

Army Security Agency 

-----------...... .-...--......-......... -...-......................... _. ....................... .--------------·-------------

l IllCl 

Dl"att, aubJ 

u a'boYe 

:r. P.boaia/Ext 215 

Lt. Oeb•e approa.cb aa indicated in thi11 dratt 

1• oxcellent.. Sotio minor changea are 1ndic!:~od 1n 

tha text. 

WILLIAM F. nusv-API 

Spec1al Aaa1et-:.nt to t.h·• C~!ef, 

ll'll7 S.ourit.7 Apr.oy 

Declassified and approved for release by NSA on 09-20-2013 pursuantto E .0. 1352a __ 
REarn:A11920 .._.. 

':OF sECri.E"r SEC REI CONFIDE:~ I A.L RESTRICTED 

OFFICE OF THE SPECIAL ASSISTAifl' 

TO THE 

ClfIEF, ARMY SECURITY AllE'.~I 

DATE_Y-4~·-

1 

!Q ,,. 

~Mr. Friedman •••••••••••••O•••a•ooo•ooo 

-.... Mr. Rh9ads ••o•••••••oo••o•••o~o•••••oo 

__ Capt. Lane •••••••o•••oooo•oo•ooo•Q•••• 

__ Dr. ~ettengill •••••o••••ooo•ooooooeooo 

Dr. Conder •••o•ooooP•oboooooooeooooooo 

=ASA Ret1ew ••••••oooooooeoooo•aoo•••ooo 

( ) As discussed 

( ) As requested 

( ) Concurrence or comments 

( ) Information & forwarding 

( ) Information & return 

( ) Information & file 

( ) lnf o upon which to base repl.7 

{ ) Recommend.at :ton 

( ) Signature ir approved 

( ) Your action by 

FROM 

·-

-

~I/ ... I / V I A../J.l'f, "'4-~C. "- ,,,/1..1--<-l_ 

.. ,~ ~~ ~{I.~ '(i U I . 

j0 Moy 1+9 V"l .~ ~-~(_ , IY-d-V-:----._ ~-~ '1-.. J..c. ... ~~ ..... -r 

__ .. \..k~, ~ ~ DIC._; ~J.-??\:'.'_ 

(J""""_,wJU> ~ o. ~t- ~: ~- t~ . T-
• 

I 

I : 

REF ID:A71920e 

Tnis should be a very useful Field Uannal when finished. 

! t·- 1 

I think the approach and treatment of the material is I 

excellent. I 

I I noticed paragraph 2 is missing. Perhaps there is a 

mistake in numbering? 

T~ere are two places in the text I beli~ve needs I 

reworking. The first is paragraph 5a on page 6. Her<!! he 

has us'ed the word artfulness where I believe another Nord I 

would be better. To rr.e the word usually rneans .£Yllning_,,, 

_ru:afti, wily, o~ tr~cky. He undoubtedly means skill in 

I design, or skill in use. 

1he second place is at the top of page 10. Lt. Geb 

is ap~arently confused concerning the relationship bE.·tween 

i degree of security and ease of operation. As you know 

well,: degree of security depends upon the cryptographic 

principle employed and the operation of the Eystem m3y I 

or may not be simgpe. For example, compare the M-209 

and ~IGTOT. 

l 
REF ID:A71920 

TOP SEx:REl' SECREr 

. ,--:> 

~ 

OFPIGI or THE SPICIAL ASSIS?AN'.l' 

TO THI 

CHIEF, AIOI! SllX:URI'l'I A'lEiCY 

Dall '(~ 

__ Ir. Friedman •••••••••••••••••••••••••• 

_..Ire Bhoad8 ••O••••••e•Oeeoe•••O••••••OG 

·--Capt. Lane •••••••••••••••••••••••••••• ...,. Dr~ Pettengill •••••••••••••••••••••••• ..l?'br• Conder •••••••••••oopoooooooooooooo 

__ ASA Rat1ew •••••••••••••••••••••••••••• 

----------------------------------------

-- -------------------------------------- -- --------------------------------------

· ( ) Ae discussed 

( ) Aa requested 

( ) Concurrence or comments 

( ) IDFonnation le .formrding 

( ) Information &: return 

( ) Intorsation & f 1le • 

~ ) Into upon which to baee :repq 

) .Racon:mendation 

). Sigmture it apprOYad 

) Iour action 1J.r 1 : .. -

.,,, :· . . • / .J •'I L ~ .;;.. t'"ti l'..J. (. ... {'_ (, f\ \ 

.,;£.,_..._,, ~ ""-· ~l \..4 '··~v .,. /? I · 

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4 .__*> t-~:....,. • . ..,.....,,. .... .. J '"'- · 1 I 

~1+...._. ... e.. '~ • .,.. ·-;>,·;·1C 

lg 

-

-

-

-

-

-

-

-
' 

e 

RESTRICTED 

REF ID:A71920 -

FM 32-( ) 

cm.mUNICATION INTELLIGEHCE 

AUD 

COMMUNICATION SECUR!TY 

DRAFT 

-- ""---

RESTRICT.ED 
RESTRtCrED -- REF ID:A71920 e 

FORE'NORD 

Modern war is notable principally for the range, speed ard flexibility of its operations which have been made possible by groat technological advancements. The complexity of today's warfare has compounded the need "of commanders at all echelons for effective intelligence services. 

Experience has dorr1nstrated that enemy signal communicatLons 

constitute the most prolific single source of intelligence which has 

been available to the Army. By the same token, it must be recognized 

that our own communications are potential sources of intelligence to 

others. Consequently, the closely interrelated fields of corrmunication intelligence and communication security, the former concerned with 

. producing intelligence from the communication of the enemy, nnd the 

latter dealing with our measures to forestall unauthorized ac:cess 

to information in our own communications, have assumed great importance 

in the scheme of National Defense. 

Today, as warfare approaches a completely scientific stage of 

dev~lopment, a general understanding of the capabilities and limitation of both of these fields must be possessed by all personnel whose 

assignments involve the establishment, operation, or use of milita:ry 

communication systems in order that the very substantial contributions 

• - f {!.,.,,.-,...,._, """""' .. " • .. • L f" .!1,. f. t I'" • 1 

which the Army's communication intelligence and-security efforts are . ' 

capable of making to the success of military operations may be fUlly 

realized. 

- J_ -
e 

RFSTRICTED 

REF Ib:A719209 

This manual supersedes chapters and , FM 11-35, 2 Septe~ber 

SECTION I 

GENERAL ' 

1. PURPOSE AND SCOPE. The purpose of this manual is twofo1.d: 

first, to assist commanders and their staffs in the prosecution of 

their I?issions by furnishing information which will enable th<Jm to 

use colllI!lunication intelligence and communication security services to 

maximum effect, and second, to serve as an operating guide to communiC.....r~ ..... ")' ... ,4.... .. ...,, .. c. ;;-tt ; .. "'"-

cation intelligence andX3ecurity personnel and units in the execution 

of their missions in support of military operations. This manual 

"7 . (!_ • f:'" ). r \..•...,., .... 1. •. JI L- 4 iC 4 ... • - lflll 

covers the fundamentals of communication intelligence and;~ocurity, 

and the divisions of responsibility which have been established for 

the production and utilization of communication intelligence and the 

maintenance of communication security. The various communicntion 

~-)1.,) -·-·.I ···~c,..1..( I ~ ·• 

intelligence and .security services available to the commandeJ1 are 

' 

described, as well as the methods which aro employed to control their 

operations. The capabil~ties and limitations of specific coimnunica- . T ~' I-•'•"' ....... r ..-.. , ,. .• l tion intelligence a~~security techniques and type units are discussed 

to assist in the preparation of intelligence and counterintelligence 

plans and directives. Throughout this manual, statements of doctrine 

are accompanied by discussions of the facts and circumstances which 

underlie the doctrine. This practice has been followed to £mphasize 

the need for the strict observance of principles or established 

practices when the consequences of non-observance are not sc:lf-evident. 

- 2 - RESTR I c-FED 
e 

RESTRICTED 

J. GENERAL. 

REF ID:A7192. 

SECTION II 

INTRODUCTION 

a. The bona fide communications of a military force are 

the most accurate, timely sources of information which exist concerning 

its plans and capabilities. They contain virtually all the information 

which must be exchanged to insure the successful execution of ~perations. 

b. Important information is usually reduced to written or 

graphic form and transmitted by an appropriate means. The means of 

communication which are employed var-3 from simple visual or sound 

systems to complex electrical transmission systems. When more than 

one means of communication is available, the specific means tc be 

employed is determined principally by the distance which separates 

the correspondents and the speed of communication which may bo 

necessary or desirable. 

c. Modern military operations are characterized by great 

mass and flexibility which have been made possible, in large ~easure, 

by the development of electrical moans of signal communication. The 

rapidity of transmission, traffic handling capacity, and ease of 

installation of certain electrical means have contributed directly 

to the development of tactics which are capable of sweeping entire 

continents, in continuous coordinated actions involving forcea deployed 

o~er extended fronts, often with no physical links between them. 

-3- RESTR I GTE: D 
e RES1~1 CTED 

REF ID:A7192. 

d. The dependence of command upon s:l..gnai communication is 

in direct proportion to the scale and mobility of operations. The 

means of signal communication which arc employed to exercise control 

are dictated by and adapted to tho nature and size of the oper:i.tion 

undertaken. Intelligence is gathered, plans are formulated and 

coordinated, men and materiel are massed and moved, battles are 

launched, controlled and won through tho ·web of signal connnunication 

which enables the commander to be completely informed of the tactical 

situation as it develops, and to remain in control of his forces 

although physically separated from them. 

S!· But no means of transmission, however efficient or 

versatile, is inherently secure from interception. In guileloss hands, 

the electrical mean5 of signal communication, especially, are two-edged 

swords. In a figurative sense, they ordinarily afford no greater 

privacy from the eavesdropper than the human voice. Radio, o~ which 

modern tactical operations loan so heavily, is a booming voice Vllhich 

addresses friend and foe, alike. Unprotected and indiscriminate 

electrical communication transmissions tell the interceptor with 

matchless accuracy of the organization, plans, and capabilitjes of 

his adversary. 

f. Foreknowledge of the enemy's intentions and capflhilities 

is the principal objective of all military intelligence operntions, 

and o,fton the key to success. Insofar as the friendly milit,ey effort 

is concerned, the usefulness of tre most efficient conununication systems 

is seriously impaired if they arc permitted to become free sources of 

intelligence to the enemy. Therefore, the employment of comnunications 

as instruments of unmixed advantage is a military objective of paramol.lllt 

importance. 

-4- RESTRt GTE.D 
RESTRIGTE! 

REF ID:A7192. 

g. The communication security effort of the Army is directed 

to tho end that its communications shall give undivided service to the 

friendly cause. The purpose of the Army's communication intelligence 

activities is to employ the communications of the enemy as instruments 

to his speedy and decisive defeat. C.. () (• 1 f I v fv I c.. -A I I 0 N 

4. RELATIONSHlP BETWEEN COMMUNICATION INTELLIGE?JCE AND Sl~CURITY. ' " _. _/ A.- "7{ I I ;(. f ·r \ ' '" ... ,"1 ~ t -r ... ~ n.r u-... "' ,. .••• · - - a...-v ~ 

Historically;_, the exploitation of communications for their intBlligence 

value, and the invention and application of protective measures were 

almost wholly uncoordinated. From tho viewpoint of the modern army, 

C..rl"'" ,,. , ..... • "'...._ l . .. -~-...; its communication intelligence and_\security act.ivitics are complementary 

and mutually dependent. Coordination of communication intelligence . 7 . ~~-) > .... ,. "'"c.-L~.... ~ t\ • ' ~ 

anc\,security activities, at all echelons, is accomplished through 

technical channels which exist to facilitate complete and rapid 

exchanges of information. Weaknesses which enablo the exploi t.ation of 

enemy communications are called to the attention of communication 

security specialists who examine friendly communications for frimilar 

weaknesses and devise effective countermeasures. Conversely, communi-

~ 

cation intelligence specialists arc appraised of newly discOVl3rod 

.... ~c...~_z, - ..... -"security principles and developments in equipment and procedures in 

order that these may be considered in the attack on current c•::>mmunication intelligence problems. Studios to determine the suitability for 

(!...-..-,.... JY...t ...... ~.,. l'<-:z... ~ adoption of no~,security-procedures oftentimes are joint comrrunication 

I c r--,.,'L-"'VI'"' C-4 ~ ........ ,._,. .. l, ;~ ..... intelligence and,..,socuri ty enterprises. Thus the full power of each 

activity is exerted to effect improvements in the other. 

-5-

RESTR I GTE. D I I 
RcsTRIGTE! REF ID:A7192-

5• COMMUNTCATION INTELLIGENCE VERSUS COMHUNICA'l'ION SECURITY OF 

OPPOS IiJG FORCF.S. 

a. In any situation, the ascendency of communication intelligence over communication security, or vice versa, d6pends on the relative cryptologic development of the opposing forces~ Ordinarily, 

attacks on the security of communications aro successful in proprotion 

to the experience and resourcefulness of communication intelligence 

agencios and the scale on ~hich their operations are conducted. 

C-r"J •.•• ' ~ ••.. c ,._ .r: ·-~~ 

. ., . Impregnability of .security, on the other hand, is proportional to tho ~""'"' , ' /. 1 "'t,... e . 'J"l-' I "T.' ._ 1-..,,{_- a._.._,..__ 

.,).. ...... · ~€i'ulness 'of communication security tJ>rocedures, the state of t.raining 

()-r'[ - '· , 

of signal communication personnel, the discretion with which ir.terceptable means of communication a!'El employed, and the con~arative technical 

~- -.... ~atu .. :1 t.~ ... ..Of opposing communication intelligonce forces. It follows, 

then, that the security of conununications is always relative, rind 

sometimes an unknown quantity. 

b. The Qbjectivo of cOJ!JJ:lunication int~lligonco services is to .,.1.,:.,.,.~~•'C? J _,,( 

-- . f'l-6 -'<-<- c ...... choose and to e91 at will thosel'communicati~ns which are of the.: 

greatest assistance to tho friendly military effort. The objec:tive 

of comjnunication security activities is to reduce the comr.mnication 

intelligence effort of opposing forces to impotence by providing 

military infonnation, passed by the various moans of communication, 

with immunity from access by unauthorized persons for tho durat,ion 

of its useful life. 

c. Efforts to protect or exploit communications take their 

direction from the frequency with which gi. ven means of transmi:;sion 

must be used and the vulnerability of those means to interceptj.on. 

-6- RESTR I GTEE) 
.RESTR IGT~ REF ID:A71920 -

• 

lleans which aro employed to effect the physical transmissi0n of 

communications provido the greatest protection from interc~ption 

because the communications which they are employed to transrait usually 

remain in the custody of trusted personnel who, by their vigilance, 

effectively prevent their exposure to the enemy. Except in unusual 

circumstances, means for the physical transmission of communications 

do not lend themselves to systematic exploitation an:i therefore yield 

little intelligence. Transmissions by sound and visual means of signal 

communication offer greater opportunities for interception, but, 

although their security is a matter of continuing concexn to tho using 

forco, the volume and value of the traffic which is passed by these 

' 

means is usually insufficient to warrant the establishment of special, 

coordinated intercept programs. In contrast, electric al neans of 

...1-d--J', C' 4° .~ ( ;,.'" I "1. 11!1.. /, , t 

signal communication, farry large volumes of immediately imp()rtant and 

potentially useful information and, of all means,, are the mr>st vulnerable to interception. Their indisponsabili ty to the conduci, of military 

operations causes the success or failure of the communication intellie .,,_.,...., v.,.... , "' ....... -....... ~ ,.... r . - .... gence and~ecuri ty efforts of any anny to be measured in terms of the 

assistance to its cause which is obtained from electrical signal 

communications, hostile and friendly. 

d. The principal factors in signal communication which 

provide the occasions for contest between tho comnunication intelliC~ , •. .,...... >-1 • • ~ • - • ~~ • • ..., 

gence andAsecurity activitios of opposing forces are the: 

(1) Need for speed in communication. 

(2) Widespread use of electrical CQmmunication and the 

opportunities which they offer for interception. 

-7- .RESTF\ IGTED 
(3) 

(4) 

REF ID:A71929 

Vulnerability of radio comr.iunications to position 

finding techniques. 

Tendency of signal corrnnunication networks to 

parallel command channeis n:nd to reveal functional 

relationships • 

(5) Need for standard cornnunication procedures. 

t6) Incidence of human error. 

6. SPEED VERSUS SECURITY. 

a. Tho requirement for speed in military comounication is 

as fundamental as the need for cor.ununication, itself. Tho inv~mtion 

and perfection of electrical means of cor.ununication has satis£ied the 

require~ent for speed. Their vulnerability to interception has been 

accepted as a risk "Which is justified by the rapidity of trans1::iission 

which they of fer. 

b. The increased danger of interception which has accompanied 

the adoption of electrical means of communication has stimulated the 

developmont of procedures to guarantee the security of the information 

which they are employed to transmit. Connnunication security procedures 

are designed, insofar as possible, to preserve the efficiency of the 

sign.91. communication system. At the present stage of development, the 

application of security n.easuros is usually separate rather t~i.an 

simultaneous with transmission and, under normal operating conditions, 

acceptable standards of speed and security can be maintained by well 

trained communication personnel. In urgent tactical situations, speed 

may become of such overriding importance that security must be abandoned 

- 8 - RESTRICTED 
e 

RESTR I GTED 

REF ID:A71920 e 

as a socondaI'""J consideration, but in each such instance, tr.e injury 

which is avoided by the relaxation of security must be greater than 

the immediate or long range consequences which m~ result from the 

exposure of classified information to interception by the enenw. 

c, The need to preserve the efficiency of signal communications at the expense of their security is the bridge which enables 

the invasion of the security of every communication system. 

7. SIGN.AL COMMUNICATION TRANSMISSIONS. 

a. Signal communication transmissions, as a whole, are 

composed of two basic ele~cnts: 

(1) The texts of messages which military corrospondents 

desire to exchange. 

(2) The cor.llJ.unication procedures which have been 

invented to facilitate the transr.d.ssion ar.d 

delivery of messages by the agencies of sjgnal 

communication. 

b, Tho texts of w.essages exchanged by military correspondants are the primary obj~cts of the attentions of both cot'llllunication 

c..,...., .... 'i.-.. 1:._=-.,_.,. ,_ '(. -· ..... 

intelligence an~security specialists. C!"JPtosystems are applied to 

the texts of messages to render them unintelligible when the,y contain 

classified information and are to be transmitted tTJ intercep~able 

means. Cryptosystems are graded in accordance with their in.~erent 

ability, under proper usage, to withstand cryptanalytic att.ick. 

Thay are distributod throughout the military orgm ization in accordance 

with predetemined requirer.ients for security and interconu:nmication. 

RESTRICTED 
.. e 

RESTR IGTE:D 

REF ID:A719209 

Low grade systems are used whore short term security is adequate and 

simplicity of operation is a prerequisite. Stronger cryptosystems are 

~~o-?n~c-/ .......... ~·~~; 

reserved for use at higher leve~s where,,simplicity is less important, 

long term security is mandatory, and important security princ:Lples cm 

be preserved from serious risk of capture. Cryptanalytic tec~niques 

vary with the cryptosystems under attack. The rate at •·rhich solution 

proceeds usually conforms to the system's inherent level of security. 

General solutions for cryptosystems become increasingly complex and 

time consuming as the enemy matures cryptologically. 

c. As sources of intelligence, communication procecural 

transmissions are second only to the texts of messages which are 

transnitted by electrical means of signal communication. Th~ mutual 

incompatibility of speed and security in communication is novrhere more 

clearly emphasized than in the development of communication procedures. 

They must facilitate the establishment of communication, and enable 

the transr.iission and delivery of messages with speed and security. 

Yet, efficiency is achieved by complete standardization of procedures, 

and security is nurtured by change. The functions of procedural 

elements must remain constant, although their identities may be disguised by cryptographic methods. Severe limitations are imposed on 

attempts to improve the security o!" comr.iunication procedures because 

signal communication operators are incapable of memorizing or otherwise 

coping with frequent, complete changes in the identities of procedural 

elements. Consequently, only those elements which are the most 

immediate sources of intelligence are disguised. The result is a 

io- RESTR I GT El) 

v 
.. .. ... e ~ESTRIGTED 

REF ID:A71920 e 

i'.!l.ixture of plain and cipher elements '-ihich, in co~bination with data 

fro~ radio position finding a~d special indcntification operations, 

yields extensive order of battle infornation and contributes to 

intercept and cryptanalytic activities. 

d. It is a fact that all emissions frora electrical r.ieans 

of s;i.gnal cor.ununication, whcthc r they are intended to convoy 

inforoa.tion or not, are sources of intelligence. All succescfUl 

~"'\.,.......~~ ..... ..,:.... ....... comr.1unication intelligence and,.,_socurity efforts are built on this 

foundation. 

I'lOTE: 

At this point a detailed treatment of the fund~montals of 

co:nunUhication intclli ;enco will be introduced. Communication 

socuri ty will bo treated in tho section ir.u:1ediatcly folloYr.i.ng. Thon 

there vlill be a discussion of tho organization and functions of the 

Arr:ry Sccuri ty Agency. The uanual will be closed ¥Ii t.h a discuss ion 

o! the capabi*ies and limi+.ations of cor.1r!'lunication intclli,5once 

a~curity ... tic!a type units. 

RESTRtGTED 

- l..l.