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COMMOBICATIOB SBCURI'l'Y 

Published b7 the authorit7 or the 

JOillT COMMTJBICATIOIS BOlRD 

Washington ~5. D. C. 

April 1947 

~IRST EDITION (7 APRIL 1947) 

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llOll-RBGIS'l'IRBD 

Declassified and approved for release by NSA on 04-30-2014 pursuantto E.O. 1352a 

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Joint CODBunicationa Boa.rd 

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'!'BE JODT CHIBPS OP STAFP 

Washington 25, D. C. 

CCllMOl'ICATIOR SECURITY 

(Short Title: JABP 143) 

1 'l'hi• publieation i• errective on receipt. 

~ JABP 143 i• a restricted non-registered publication and shall be aareguarded in accordance vith current instructions tor the safeguarding or reatri~ted documents Periodic accounting i• not required. 

3. JA1'P llf.3 •Y not be carried in Aircraft tor uae therein. 

4. Approved in principle by the Joint Deputy Chtera or Statf' and published by the authority or the 

.TODT COMMUKICATIOl'S BOA.RD 

Washington 25, D. c. 

April 1947 

E. B. PIERCE 

Captain, U.S. navy 

GERALD CARLISIB 

Lt. Col , Sig. C. US Al'lllJ" 

.TODT SECRETARIAT 

"'l'hi• document contain• intormation arrecting the national defense or 

the United States vithin the meaning or the Espionage Act, 5~ U S. C., ~l and 32, a• amended Its tranami•aion or the revelation or it• content• 

in any manner to an unauthorized person is prohibited by law." 

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INTRODUCTION 

Intelligence is an offensive weapon, one which searches 

out the vulnerable points in a nation's armor, and attacks 

strong points again and again, until they, too, are made veak 

The only defense against intelaigence is security and no form 

or security is more important or more effective than communication security. 

I~ the words of Frederick the Great, "Ir one co~ld always be acquainted with the enem~•s designs one would always beat 

him with an inferior force And, in the words or a German of 

more recent vintage, a prisoner of the past war, "Ir U S 

troops vin the war it vill be in spite of their coanunication 

security and not because of ib " 

The establishment a~d maintena~ce of coanunications 

security is a function of co11111Bnd, a function that unfortunately is not always understood, not always correctly per- formed This pamp let will attempt to bring home to all officers 

their past defic ncies in comm~nication security and the steps reco:rune~ded to c rrect them. 

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!BB COIOIAIDBR•S RESPOKSDILift--COJllllJllICA!IOll SBCURI'l'!' 

Ever7 COlll8nder. regardleaa ot echelon. 1111at be vit&ll7 concerned vith 

aecurit7 in all ita pb&1e1. tor ever7 COllll&nder ii con1tantl7 receivina: and 

di1aeminating claHif'ied inf'ormation. Without a aecure cammun1cation 17ata 

the commanding otticer ot a modern armed torce cannot 1atel7 tran1mit intor1111. tion to. or receive inf'ormation tr011. c0111Bnder1 ot other units. 

'l'he measure• tbat a COllll&nding otticer ewplo71 to prevent compromi1e 

or the trattic hand\ed b7 the 171ta1 ot hi• unit conatitute com1Unication 

1ecurit7 Eia re1ponaibility in thi• regard i• abared to a certain degree by hi• cryptoaecurit~ and communication otticer1 but becau1e ot the highl7 important relation or 1ecurit7 to tactics. the commanding ottioer hi111elt 

ha1 the tinal re1pon1ibilit7. 

SECURI'n II • S'fAlPll' WORK 

Communication aecurit7 ia detinitel7 an item tor 1tatt con1i4era.tion , and understanding. The commander 1hould take communication probl•• into 

the conf'erence room.a a1 an operational part ot COlllBnd. Be 1hould require hi• security per1onnel to 1111.ke periodic reports ot how 11Uch int'ormation baa 

been ezpoaed to the ene117. Thi• inf'ormation 1hould be conaidered vhen •king •ilitar7 deciaiona. !he atatu1 ot aecurit7 ot co1m1unication1 should be coordinated with various 1tatt aectiona. part1cularl7 operation1. 

It i1 obv1oual7 adverse diplomac7 tor a junior otticer to tell hi• senior 

9ttioer what he can. can't or mu1t do. However. it ii the dut7 ot the junior \1tatt otticer) 10 to 1nfo1"11 h11 superior (commander) regarding COlllllUDie&tion 

1ecurit7 tbat the commander decide• and act1 vith kQ.ovledge and not in ignorance ot ri1kll involved. Completed atatt action in thi• oa1e ia a detinite 

"11111t." and the CCllllll&nder 1hould demand it. 

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!he tinal reaponaibilit7 ot com11&D4 tor communication 1eourit7 cannot 

be delegated. Bovever. it ia an unvi1e o~nder vho atte11Q>t1 to do all the 

work or hia atatt. Regulation• permit him to appoint an otticer ot hi• 1tatt 

a1 the 1eourit7 otficer. crypto1ecurit7 otficer. ~op Secret control officer. 

or c01111Uni"C&tion 1ecurit7 otticer. Thi• otticer then i• re1pon1ible to hi• 

commander tor the e.zecution ot hia appointed ta1k. !'he importance ot hi• job 

cannot be overempha1ized. Perh&pa the moat important job ot an otticer in thia 

position is that of c!'J1)toaecur1ty. Actual examples ot in1ecure Cl'JPtographic practices point out the necessity tor strict control ot meana ot conaunication. 

1 Pailure to Report Lo•• ot Codes or Cipher• 

l'or eight c!a711 a m1litar7 code vaa used attar it bad tallen into 

the hands ot the en9117. becau1e compromise vaa not reported 1mmedi&tel7. 

as required by in1truction1. Portunatel7. it va1 a 1pec1al-purpoae code 

not ordinarilJ' used tor aecret tra.ttio. but the c!a•ge •igbt have been 

very great ~ere i• no va:r of knowing how great it actually va1. 

2. Discretion in Destruction 

A naval vea1el was engaged in a running battle with en91Q' cratt in 

the English Cbannel. Comidering the relative po1it1on ot •hip. ene1117, 

the rockJ' French coa1t. and other circumatancH. the cOU1111&1Jding of'ticer 

4eo14e4 tb&t to jett~aon the .registered publication1 vaa a nece1sal"J 

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precaution. When the order to jettison vas given, one sack ot pub- 11ca tions landed on a submerged rook. '!'ha aack broke open and a avitt 

tide acattered the :publications tar and vida. Subaequentl7, mny or tbe 

publications were recovered through the ettorts ot other naval veaaels. 

Some were picked up b7 French tiahing veaaela, othera were found along the shore. Some were never tound and aupersesaion at mn1 publica.tlona 

was necessary While it 1a ditticult to criticize acta cbmlitted under 

such c1rcumatancea, it muat be pointed out that both inatructions and 

good judsment require that jett1aoning be done in deep watera. Bad the 

publication• been put over the aide earlier, considerable inconvenience 

to allied communication& and the expense ot replacement ot compromiaed publications might well have been avoided. 

3 Use ot Superseded Publications 

Because a superaeded code vaa uaed to transmit a warning, anArm.7 

bomber group in the China-Burma-India Theater nearly came to di1a1ter 

during the var The group vaa on ita way toward K,.uahu in Japan and 

had.been gone about two houra when the Nav1 reported a Budden hu:rricane 

ott the Japanese coaat. All tielda were ordered to aatablish comuniction with their planaa and change the target to Shanghai. Bach base 

notified its planes without incident except tor one baae, which encrJPted 

the hurricane meaaage in an obaolete code. lftle planes operating trom 

that base copied the measage readil7 enough, but reported that they could 

not decrypt it. The crJPto otticer at the base was not in the cryptoroom, and the nature ot the ditticulty could not be determined at once. 

By the time the measage had been encrJPted correctl7 it was too late. 

The planes were be7ond the range ot communication. Unwarned, they rode 

into the hurricane, narrovl1 eacaped destruction, and had barely enough fuel to return to a China base. By just o.ne err9r in the use o1' a CJ"J'Ptosyatam the lives or 300 airmen were thus jeopardized and the ettorta ot 

2,000 men expended uselessl7. • 

-· Loose Handling or SOI 1S 

Tvo bombers crashed into the sea Yh1le on a training tllght. Bach 

carried a nearly complete set ot signal operation instructions. As a 

result, the SOI•a issued b7 the bomber command were compromised tor a 

period or several da7a. 

A pilot returning trom a training tligbt diacovered tb&t a portion 

ot an SOI tolder vas missing !'he radio operator was or the opinion that the portion was not in the tolder vb.en it was handed to him. However, it was necessary to report that the missing SOI possibly had been 

compromised, since no check ot the contents or the tolder 'had been ma.de 

prior to the tlight by the issuing otticer or the operator 

Certain 11gna.l operation instructions contain intormation ot extreme 

importance to the enemy. 'l'here~ore, crew members on tactical flights are 

permitted to carry OILY those extracts ot SOI•s which ar~ necessary tor 

pursuance or immediate tactical operations. Precautions which are necessary tor tactical flights should be observed during the training period and commanders must assure a realiatic approach to all security practices during training exercises. 

5 Use ot Unapproved Codes and Ciphers 

It is an obvious truth that precautions must be ~baerved in co1111idering plans tor operations. Without security it would be impossible to 

achieve surprise 1n attack. Codes and ciphera are turn1shed to a commander so he can achieve surprise and cortrol his forces, without his 

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intentions beirlg known to the enemy or to those parts or hi• ovn forces 

vhich should not know future operations. The preaaure of var m&J force 

ua to use leas secure cryptographic a7atema. 'l'b.e commander therefore 

should be aware of the wealcneaaea in those systems upon which he ma.1 be 

f'orced to rely. Be should prevent the use of' locally produced Ol"JPtOgraphic schemes Bathing can lead to more trouble than rel7ing on a 

crypto-aid which cannot 1tand b'fore an enelllJ expert. Only approved code• should be used within the services. 

SECURI'l"f I1' 'mE USE OF DA.BS Oll' TRANSJIISSIOB 

Because commanders are ~arced f'or the moat part to rely on electrical 

communication• to ettect the dissemination and receiving of' clasaif'ied information it will be well to determine juat how private these mean11 are in 

order that the in1'o:rmation which baa been encrypted, and even the crypto- BJBtema themselves, may accomplish the desired purpose and not become ineffective through disclo1ure or compromise. 

Wire transmission i• rightly considered to more secure than radio, but 

only because interception of' radio transmission is so much easier, not because 

vire lines are tree f'rom inte~csption. 

Interception on-vire lines is a f'requent and important source or intelligence. Wire tapping often may be discovered through pb7sical examination or from'transmiasion irregularities, b11t interception bJ induction can 

escape detection completely. A supposedly secure communication circuit or a 

physically checked wire may still be intercepted by use or a concealed coil 

ot vire placed as tar as aix reet frOll the oOllllUnication line -- even if' the 

six feet con1iat of rein1'orced concrete. 

During the var the Germans co11Bistently used many clever tricks to 

intercept communications and to conceal the tact that interception vas going 

on. '!'hey placed carefully hidden taps on wire lines v'b.ich they vere abandoning and which they knew advancing Allied troops would use tor their ovn 

communications. In one instance the Russian• found a communication system in 

splendid condition in a village evacuated by the Germans, but careful e::ramination shoved that something had been added. A buried cable elttencled from 

each encl or the village circuit. They learned later that the Germns bad 

made a large arc with the village line aa the center, the buried cables forming the ends or the arc well within the German defenses. 

The uae of' radio to a point where it has become the prime means of' 

electrical cOlllunication has had a profound ef'tect upon communication security. 'l'he speed, range, and ve~satility or radio have kept communications apace vith the mobility ot modern warfare. But the uae of radio bas also exposed communi~ations to their greatest da:nger--radio transmission• can be intercepted by friend, neutral, and foe alike '1'b.e mere tact that a radio station 

is on the air is a source of' in1'ormtion to the ene117r 'l'b.e elttensive use of 

intercept stations and direction finders enables the enelllJ to record every transmission that is made and to log the place or its origin, thereby giving 

him an opportunity to follow troop movements and to learn the identity, strength, plan or tactical disposition of' a military f'orce. 

' A single electrical impulse may indicate the eltistence of' a unit Upon 

one occasion during the North Af'rican campaign, several aircraft vere sent on 

a miaaion and every precaution had been taken to concea~ the size of the 

flight. While enroute a radio operator on one of' the planes carelessly tapped his key Another operator thoughtlessly responded by tapping his key twice. 

The resinder or the operators in the tlight eagerly entered into the •game," each adding a "dit" to his reaponae. All previous ef'f'orts to conceal the 

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flight ware lost since this "harmless" game disclosed to the listening en911J" 

the exact num.ber ot aircraft in flight without a meaaage being sent. The 

mission was unaucceaat'ul and serious loaaaa resulted. 

LOCATIOB BY RADIO 

Direction finding today ia more ettectiv~ than many officers realize. 

Although radio silence can be car'ried too tar, it has lost none of its importance. Testa of captured equipment show that it ia possible at a distance of 

100 milaa to locate accurately by direction finding a 50 watt VBP transmitter. 

Forward observers and naval guntire liaison otticare reported that the Germana 

poaaeaead attective D/P equipment and were able to locate key radio stations 

and subject them to tire in a matter of aeconde, according to an official 

report trom. one sector. Beach patrols thought it expedient not to use their 

radios until attar German batteries bad bean driven out ot range 

In the North African campaign, a U.S. tank destroyer battalion waa moving into poation to attack, and radio silence was ordered. Attar several hours, , a detachment trom the battalion realized it was lost and broke radio silence 

to verity ita position. !l.'bat enemy direction t'indera were on the alert i• 

evidenced by the tact that a aubeequent air attack wiped out the entire detachment. I 

Waval'vesaala also suffered aa a result of ill-advised uae ot radio. 

Over-uee or radio was given aa one reason tor the loaa ot ten Allied aubmarinea in the Med'iterranean during the early month• or the war apinat Italy. PT boats were often bombed by float planes immediately attar radio tr&Jlamiaaiona although the planes bad previously passed overhead several times 

without attacking. Submarines operating in the Pacific noticed on several 

occasions that use ot radio brought a patrol boat or plane to search in the 

vicinity the next day. One submarine reported that.a radio tranamiaeton led 

to both aircraft and surface interception•vithin 17 hours. "Wum.eroua close 

Jap radio stations aeam.ed to D/P the eubmrinas quite accurate.L7, 11 one report decJ.&red. 

A veaael in the ~uropean Thea~er bro.lee radio Bi.Lenee to report a rudder 

caaua.L'ty. Thia report could have been cieared later b;y visual methods. In 

another caae, radio silence vaa broken to report a small hole in the ahip'a aide, well above the waterline, the aea being quite calm at the time. The 

operation plan specifically stated that strict radio silence ~a• to be maintained and that submarine and other enemy contacts vere to be reported by 

vieua.L •tb.ode. 

Under aame circ1.m11tancas radio silence ma7 be leaa illlportant tor plane• than tor surface ehipe. Failure to observe radio silence, however,. m.7 

diacloae a flight which vould otherviae aurpriae the enemy, and insure tor 

the planes a deadlier reception while performing their miaaion than they would otherwise encounter 

RATIONALIZING RADIO SILENCE 

Although it ia one ot the moat effective components ot communication 

security, radio silence can be carried to the point where it becomes a handicap rather than a protection When it ia reasonable to assume that the ene117 

ia unaware or the presence or precise location ot a taak force or ship and 

does not anticipate the operation which ia about to commence,. the breaking or 

radio silence muat be ordered only aa a calculated risk. Hovever. when it ia 

certain that the eneaay knows the locat,on or anticipate1 the movement• 

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ot a ship or taak torce. or vhen contact baa been made, there 1• little to 

gain by radio 1ilence. Dispensing with tighter direction in order ~o preserve radio 1ilence vaa given ott1c1&117 a1 one or the factors contributing 

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to the 1011 ot a United States crw.iaer early in the var. Obael'V&nce ot radio 

silence upon the occasion ot a positive en8Dl)' contact shows a lack ot appre- ciation ot the offensive action expected ot units ot the fleet and jeopardizes the safety ot all other units in the vicinity. 

A JAPANESE COMMEB'l' 

Eloquent testimol)V on the subject or radio silence vaa ottered in a 

Japaneae broadcast beamed to the United Statea from Batavia in the 1'etherlands 

East Indiea during the var. It read in part as follows: 

"It the Americans are so eager to tight the Japanese Navy, why do 

they dive into a complete radio silence as long as they understand that 

the Japanese Wavy will come out and meet them'l rt one •Y believe the 

Americans, there were not many Japanese ships at Truk when they attacked 

there. Notwithstanding the tact there were only ••11 unita ot the 

Japaneae fleet, and notwithatanding the tact that the Americans announced 

the attack on Truk as a crippling blow, they kept a complete radio silence 

as long as they were within the reach ot Japanese forces in Tl'uk." 

SUCCESSES OF JAPOESE IBTELLIOD'CE 

Interrogation ot Japanese intelligence otticers brought to light a 

number ot useful tacts about the 1m.ture, extent, and success ot e119117 ettorts 

in the field ot communication intelligence, especially trattic a1m.lysis. One 

ot the otticers vaa Commander Bideo Ozawa and the other was Lt. Comdr. T. 

Satake Both held key posts in the radio intelligence section ot the Japanese Waval General Statt during moat ot the var. 

Ovada was the center ot the activity deacribed by Ozava and Satake. Bera 

Allied transmissions were intercepted, copied, and sorted by areas. There 

were seven ot these apeas--the vest coast ot the United States, the Indian 

Ocean, and five different sectors ot the Pacific. Several otticera were aesig- ned to each area. 

Tratt1o waa a1m.lyzed according to call signs, cryptosystems, plain language, total volume, proced\lre sig1m.ls, and precedence. Volume and pre- cedence were plotted on a chart, one tor each area. Though usually u1m.ble to 

decide whether transmissions came from ships or shore stations, enemy analyst• used direction finders to determine the point ot origin. 

United States operators were often identified by individual peculiarities in sending. As a rule ahipa could not be traced, however, presu•bl7 because 

rsdio silence prevailed quite generally. The enellJ' a1m.lysta were not able to 

eati•te the strength ot our forces in various theaters. It a force broke 

radio silence, the enem7 would start a new search in the area. 

It was realized that a peak in traffic represented "a crisis." !'he 

interpretation "waa completel~ dependent upon the tactical situation," 

however, and the Owada officers •could not tell where that crisis would 

•terialize n 

Takirur Ok11m.wa as an example, Satake ~de a statement translated aa 

follows: · "'A month before Oki1m.wa, BlllS***lRadio Broadcast) had a notable 

' increase in transmisaions. Ten days betore the Okimwa operation, there waa 

a •rked increase in aubma.rine reports. !'heae are eas7 to spot because we 

got good d1rection-tincle:r rtxea aa the7 are close in. 'When submarines changed trom routine operatio1m.l communi:cations to urgent, we deduced that perhaps an 

air strike or la11ding might be in the otting, depending on the tactical 

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Ozawa, when asked v'bat vae the greatest eucceee ~ rm.val radio intelligence in predicting tuture operatio1111, rm.1184 the .Marshall• operation. "We 

got the vord to the garrieo1111 in ti• to be or some help that they should 

prepare tor an attack,• he stated. Regarding the ba•i• ot the prediction, he eQlained ae tollove: •Bombing grew inte1111e. Both ship and aircraft 

volume or radio tra1111mieeione roee to a peak, and we vere able to pick up a 

tew plain-la~ge broa.dcaete. I remember one aaying General Olda would 

arrive 1hortl7. 11 Aaide trom •aome minor eucce11 in predi9ting the Iwo Ji• 

landing,• Ozawa claimed little or no eucceaa in other operatiODll. 

Air-to-air and air-to-ground. coded int"ormation vae received and "we were 

able to interpret much ot it," but "the rapidit7 vith which aircraft code• 

were changed cauaed contusion to ua," Ozawa stated. Our aircratt often gave ava7 our plana. When B-29• prepared to take ott "there vae much adjuating 

ot radio trequenciee." Moreoyer, "weather reconnaiaaance planea which pre- ceded large atrikee gave an indication ot the large strike by the volume ot 

data aent back to it• baae. 11 Ozav& CJ&imed 50 percent eucce11 in •kins 

predications baaed on weather recormaieeance flights. 

It may have been due largel7 to our aetenaive measures againat trartic 

ana1ya1a and also against interception and direction finding that the en&mJ' 

did not learn more and vaa aeldoaa certain ot the deductions that he felt 

justified in qiaking. 

In this treatment ot radio security a particular and aeparate empbaaia 

must be placed on the proper uae or radiotelephone. During the aecond world 

var ita incorrect usage constituted one or the moat vulnerable apota in the 

security armor or communications. Too much enu>haaia cannot be placed on the 

need tor extreme securit7 cohaciouaneaa in the uae or radiotelephone, tor the 

tact that such equipment can be operated b7 other than trained personnel increases the need tor adequate control and complicates the problems or good circuit discipline, correct procedure and strict adherence to all security precautiona. 

The security or voice codea is comparatively limited even though they 

are prepared by expertli and otticall7 approved. 'l'b.1• 1• due to the neceaaity tor sinu>licity. However, the outstanding difficulty encountered in the 

security or voice codes can be attributed chiefly to the so-called private organizational codes. This vas clearly demo1111trated in operatio1111 in Sicily and Italy Intormation obtained trom prisoners indicated that the Germana wer~ usually able to tt.gure out these private codes rather easily. Veiled 

language is scarcely more ditticult tor the en91111" to understand than tor the 

person being addressed. 

Use or a toreign language does not provide any measure or security aa a 

rule, although U.S. forces are said to have uaed Choctaw and Wavajo Indiana 

as telephone talkers quite auccesstully. The British used le.tin aa a •keahitt during the Boer War because the7 knew the Boera were not tam111&r vith 

it, but the Boers would certainly have tound someone vho vaa if the British 

had depended on le.tin very long. 

'l'h.e miataken idea that voice radio tranamiaaiona are more secure than 

keyed transm1asions ia one or the moat treacheroua illusions in the field or 

electronic communication. The insecurity or VBP tra1111miasions vaa not gener- ally realized during the earl7 years or the var. Thia tact explain• in part the tendency to use voice radio circuit• too much and to transmit 1ntormt1on 

which should not have gone out on the air, even in a voice code. In 1945 a 

headquarter• ship on a tvn-veek VOJ&ge from Ivo Jima to Pearl Barbor vas able 

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to log each day VD' tranamisaiona trom Iva, the Ryukyu•, or the Philippine• 

tor eeveral hour• a day until the day betore it arrived. The mzimum range 

at vhich eol1d •ignals were picked up vae 3700 m1lee. The more a commn4ing otticer knows about l'&dio wave propagation at varioue trequenciee, the more 

discreet and judicious he is likely to be in bi• uee or voice radio. Hie i• 

the direct reepon•ibility tor its secure uee. , 

VBP, lJHP', and SD deeign1J.te epecif'ic band• ot "vfry higb., 11 "ultra high" and "euper high" trequencie• \30,000 to 30,000,000 kcJ Which are eJJg>loyed 

tar the very reason that their normal ra.nge i• limited ro~ly to "line ot 

•ight. 11 Instances continue to accum.ulate, however, ot verif'ied reception 

at distance• ot several thousand milea. Thus, even though higher trequency band• nol"lll&lly provide more limited range characteriatic• than the lover 

trequenciea, they are not aecure enough to juatity use ot plain language which on lover trequencies would have to be encl'JPted. Voice transmissions 

on any trequency are, in reality, lesa aecure than CW on the aame trequency becauae anyone can underatand them--without knoving the telegraphic code. 

Careleaaneaa on VBP leads to careleaaneea on MP and BP voice circuit•. 

The tact that radio ia the least eecure ot the means used tor transmitting meaaages •ke• it neceH&l'J' tor anyone uaing radiotelephone to be 

thoroughly versed in radio procedure. Radio procedure ia f'ormulated to 

insure a rapid and accurate method of' transmitting and receiving messages in 

a briet, detinite and unitorm languaC. In the interests of' aecuritf, no 

variation•, elaboration• or ahort cu a on the preacribed procedure ahould be 

authorized. 

In order to prevent the enemy .trom gaining much into:i'aat1on tram his 

obaervation ot radio activity, the principles ot radio aecurity have been 

developed. !l'heee principle• a'l'e grouped into f'aur categoriea: Discipline, Silence, Deception and Interterence. 

RADIO DISCIPLIIE 

Hadio tranamiesion security embodies the maintenance of' circuit di•cipline and the auppreasion ot all aupertlnou• tranamisaiona. '.rb&t component ot radio 

tranam1aaion eecurity which include• the maintenance and proper uae ot radio 

equipment, the adherence to preacribed procedure vhen operating ati.d the 

emplo1111ent ot remedial action when and where neaeaaary by the net control 

etation or other responsible agency i• known aa circuit or radio discipline. Corrective meaauree taken tO"~&rd the suppreaaion at excesaive transmission• 

are tOl"lll.ulated on the b&ai• ot :procedUl"e an&lJ'BiS ot mon~tored •ter1&1. 

Security monitoring loga are analyzed tor deviations tram prescribed pro- cedure to determine trend• in violations. Analyaea indicate the nature and 

extent or corrective action to be taken within the unita concerned. Radio 

t1'&nBmiaaion security is attained by the tallowing: 

1. '!'raining radio operators in the principles or cil"Cuit discipline. 

?. Monitoring transmi••iona ot our torcea. 

3. Instituting remedial action f'or security violations vhen and where 

neceaaa.ry 

Hadio discipline requires more than blind obedience to the rules. It 

includes active imagination on the part of' an.yo.ne using radiotelephone in 

order to deny all inf'ormation to the enemy vhich may help him an&lJ'Ze the 

mesaage intercepted. It ahoul4 be 111Presaed that continued alertness muat 

be the watchword or all conaunication peraonnel. It vaa an alert German 

operator vbo noted, during the tirat world var, that the shore atation at 

Scapa Plow broadcast weather reports onl7 when Grand Pleet unite were at sea. 

Be thus could advise the Oel'lll&nAdmiralty when British ahipa lef't their base. 

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There are baaie rules that should be remembered and tollowed by anyone using radiotelephone. While these rules and m&llJ' more should be instilled in 

trained radio operator•. these should be ot particular concern to the ott1cer 

vho. on occasion. used radiotelephone. 

1. LISTER BEPORE SPBAKDG. Failure to do this C&UHB loH or t1m.e and 

makes additional tranem.ieeione necessary. 

2. SPEAlt CLEARLY. .Clipped speech and jamm.ed-together vorda are ditticult 

to understand. 

3. SPEAlt SLOWLY. Must be slow enoup to be copied without "repeate. 11 

"'. SPEAlt EVENLY. Bot in a monotone. 

5 KEEP 'l'HE DISTA'RCE FROM MOU'l'B TO MID '1'JIE SAME AT ALL TIMES. Inex- per1~nce4 personnel otten tail to realize the importance or thie detail. 

6 MAINTAIN A 'RATURAL RHYTHM. Group words and phrases in a norml 

manner Transmit phraee by phraee. not word by vord. avoiding "er••" and 

"ah'• " 

7 USE STAimA.RD PRONUNCIATION. Standard speech without, aect,ional peculiaritiee ia moat easily understood. 

' 8. "JEEP !RA.'RSMISSION TO A MINIMUM. Avoid crowding circuits with excessive call-ups. receipts. tuning. teeting. and unnecessary repetitions. 

9. USE S'l'AWDlRD PBRASEOLOOY. Continuea use ha• •de 1.te meaning• unmistakable. 1'1ckna•• and h.nc7 language are cont'using and leH briet. 

10. DCL'IJDE Slll'PICD'RT ID'ORMATION. MeHages omitting necenary int'ormation are vOl'thleee. 

11. DO WOT CCllPROMISE VOICE CODES. 'Raver state in plain language what 

ha• just been tranamitted in voice code. ' 

12. USE PIAD LA.l'GUAGE WITH THE GREATEST DISCRETIOI. Futrure operations have sometimes been diecueeed on voice circuits. An instance at Tarawa gave the enemy advance warning ot landing• planned at other points aubeequent to 

the initial landing. 

13. DEMA1'D AU'l'llDTICATIOB 'WJIDEVER 'l'HERB IS CAUSE POR SUSPICIOB. Do not 

allow enemy attempts at deception to eucceed. Be can speak excellent English when the need arises. 

SILDCE 

Aa etated previously. radio eilence is the primary detenae against interception and direction finding. Both interception and direction finding 

are now ettective on nearly all trequenciee A tranamieaion ot onll a rev 

1econd1 duration 1• sometime• autticient tor obtaining a bearing. void all 

uzw.uthorized tranemtesione and unnecessary testing. 

DECEPTI<>I' 

Although adaptable to any meana ot communication. deception ia employed chiefly in connection with radio. There have been many inetancee in which 

the enemy ha• attempted to disrupt cOlllllUnicatione to prevent a message trom 

being deliverecJ. divert our t'orcea or draw them into a trap. Enemy methods 

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include anavering call-upa and ottering to accept trattic, receipting tor 

meaaagea vhich our atationa have not been able.to copy, tranamitting talae 

oJ'dera by voice or radiotelegraph in plain language and originating measages pieced together trom part• ot intercepted meaaages. 

The greateat detenae againat enemy attempts at deception i• the correct ua~ ot authentication Incorrect authentication undermines communication• and 

invite• deception, eapecially in combat when aeconda count. Evan an occaaional 

error tar trom the acene ot action is a serious matter. It delays traffic and • e~courages operators to distrust or diaregard an important meana of protection. A vital message may be disregarded. 

An incident illuatratea quite clearly vhat could happen in actual combat: 

"During maneuvers, the artillery in a Blue division dropped the uae of authenticators. The radio operator of a Red division paased himaelf off aa the Blue 

net-control atation ~e received location or units, plans of tire, and future 

•ovamenta; he directed fire into an empty tiald and along an unoccupied ridge, he persuaded the receiving operatoF to ignore the frantrio calls or the real 

net-control atation, and finally created so much confusion and mutual diatrus~ 

among the Blue stationa that radio co11111unicationa broke down completely." Unleas radio operatora are thoroughly instructed and wall-trained in the uae 

of authenticator• !'HEY WILL MA.KE MISTAJCES. In order not to forget about 

authenticatora it ia neceasary to review inatructiona and PRACTICE them 

Japanese deceptive ingenuity in obtaining information from AAF radio 

operatora waa revealed by reporta from the Central Pacific. A B-29 which 

participated in a miaaion over Japan gave ita altitude, courae and speed in 

responae to a radio query, apparently from a plane that had become detached 

trom the formation Immediately the formation experienced intense and accurate 

antiaircraft fire. This could have been avoided by proper authentication 

Another B-29 on a later mission, in reply to a a1milar query, gave inaccurate 

information vith the reault that antiaircraft fire became "intenae and accurate" 

at an altitude tar below the B-29 formation. 

Appropriate training manuala contain meaaurea deaigned to prevent enemy interference from aucceeding Listed below are some of the more important 

ones to be ra~~mbered by commanding officers as vell as radio operators. 

1 Improve procedure and circuit diacipl1ne. These should attain such 

perfection aa to nullify any attempt by an enemy to imitate procedure 

? Demand authentication whenever there is call for auapicion Plain 

language is more vulnerable to deception than encrypted traffic. A 

requeat for authentication vill usually expose and silence the most 

determined effort of deception. All personnel using radio must be able 

to authenticate PROMPTLY AWD ACCURATELY 

3 Keep accurate loga. 'l'hese vill be useful in studying suspicious transmiaa1ona. Much can be learned from them. 

4 Do not reveal the precedence of measagea awaiting tranamisaion if 

thia can be avoided. Doing thia may invite interference if the pre- cedence is high. The enemy may try to accept the mesaage, receipt tor 

it or jam the tranamiasion it all else fails. 

5. Keep procedure meaaagea and service mesaages at a minimum Theae 

help the enemy to learn our procedure and meanings ot operating signals, thua making imitation comparatively easy. 

6. Respond promptly on call-ups. Long call-ups 'are an invitation to the 

ememy to come in on a circuit. 

7. Report all irregularities at once. Thia may help in discovering 

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whether the intertering station ia genuine or not. It it ia not. this 

might also help deatro7 it. I 

"During the 'l'arava operation. a Japanese operator took over the 

the call ot the c~ncler ot one ot the transport divisions and 

and save orders to land troops and supplies to the veatvard ot a 

certain pier. !'he position ot Jap automatic weapons at that tille 

vaa such that this vaa the worst place to land. !'he operator vaa 

alert and. auspicious. Be de•nded authentication. When this vaa 

not torthcoming. an urgent vaa broadcast to diaresard this deception and the Jap atteDQ>t tailed. Thia illu1trate1 the neca11it)" tor 

constant uae ot authenticators during such periods." 

8. In resard to rad.iotelephona. r--ber the two basic a11umptions that 

must alva7a be considered whenever radiotel•phona or wire circuits are 

used. 

a. All telephone calla over a circuit which baa a radio link 

will be heard b7 the e119117. 

b. All telephone calla over wire circuits 11!% be heard b7 the 

ene1117. 

"A telephone circuit which had a radio link vaa monitored tor three 

hours. Headquarters !'hird l7. S Arm7 diacloaed that during this briet 

period auttioient 1&ter1al waa provided 'to enable triendl7 monitors to 

eat&bliah a tairl7 complete peraonalit7 tile tor this headquarters. almost the ccmplete order ot battle to!' our hisher echelons. and the 

exa.ct coordinates ol this he&Clquartera advance C?!!!lnd post ona d&1 

prior to ita opening 1 " 

Having treated the coana.nd tunctiona in resard to signal 1ecurit7 it 

would be well nov to turn to the originator and determina hia position in the 

over-all pattern ot aecu'f'e and etticient communications. 

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CHAPTER II 

THE ORIGINATOR AND COMMUNICATION SECURITY 

The miaaion ot a military communication aervice ia to provide reliable, 

rapid and secure communication to command The moat direct, and often the 

only, contact that many officer• have with communications is in the dapacity 

•or originators.or addressees of mea~ages. It ta essential that those who use 

this service are aware of and observe the relatively few basic rules which will 

assist materially in the accomplishment of this mission. 

Messages which make the grade on security counts will usually be found 

sattstactory by any other communication standard Communication security beg1ns with the originator His skill in drafting a classified message has 

an important bearing on the security or the ciphers used. If he has learned 

the secrets or brevity, his message will take less time to encrypt, transmit, 

and decrypt The net result of similar skill on the part of all ortgtnators vill make a surprising improvement in the speed with which messages are transmitted and delivered Clearness and exactness also pay dividends. A message which is not clear causes misunderstanding or necessitates a service message It the messages are classified, security suffers, and in any case the over-all 

speed or communications is reduced proportionately 

MUST IT GO BY RADIO~ 

It is obvious that if no messages are originated no security problems exist. This happy state ot affairs cannot now be anticipated It is possible, however, to keep a large proportion of communications out or the most rapid, 

yet most insecure methods ot transmission. The first responsibility of an 

originator ts to specify another but more secure means or communication than 

electrical whenever circumstances perm.1~ He can thus cooperate in keeping overloaded circuits clear enough for maximum speed when minutes are really important. By such cooperation he will use messenger service in the t~eld 

in preference to electrical communication whenever practicable At sea he 

will make maximum use of dispatch boat, message drop, or visual means, depend- ing on the length of his message, weather conditions, radio silence requirements and other factors On shore ha has a raat mail service or unlimited 

capacity at hia diaposal, at least in the United States, or he may employ guard mail or air courier services and sometimes diplomatic pouch if he is in a 

foreign country. 

U S mail service frequently equals the speed of a lov precedence message. I~ continent&l United States no two points are more than a day apart for mail 

planes, and the U S postal system ts sufficiently s~cure for moat conf'1dent1~1 

and secret communications. 

Before using radio or any other electrical means of communication, therefore, an originator abould 1nvar1ably aak himself, 11 ian 1 t there some other way 

ot getting thia message to the addressees which will serve just aa vell and is 

at the same t_!me mgn secure~" Sometimes methods other than radio are taster. 

Thia has been the case vith visual methods more than once during landing operations. and the aame has prQved true tor mail plane service in advanced 

areas as well as in the United States. 

WHO REEDS TO DOW'f 

The second responsibi11t1 ot all vho draft or release messages ia to 

'keep addreasees at a minimum. Unnecessary addressees lengthen the text or 

the beading unduly, and otten make it necessary to relay a measage on more 

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RBB!PR!9!9B JANP 143 

circuits than would otherwise be required. Sometimes a more widely held and 

therefore less secure cipher must be employed bedkuse a remote outpost is addressed. 

Failure to include an addressee who needs the intormation a message contain• can be pqtentially mQre ha'l'mf'ul ~o security, however, tban unnecessary addressees. The reason is that it may be necessary to re-encrypt the mess~ge 

in a different cipher tor an addressee whom someone thought ot too late. 'l'Jle 

dangers ot re-ttnorypt1on are well known Any progreas an enemy may have made 

in breaking one or the systems can be applied to the other vhen a re-encryption is detected. 

The tend.ency toward including too •111' addreHeea 1a international. 'l'he 

rolloving statement was round in 1944 in the notebook ot a Japanese officer: 

"The purpoaeleH designation or addre11&eea on a grand scale complicates the ~xchange ot communications and leads to an increase in 

the number ot •••ages." 

Truer words were never spoken. Here again it is the originator to a large degree who determines the speed and e:tf'iciency or b,,is servant, the communication 

system. 

BOW' 8001' MUST IT BE AC'l'ED 01'7 

A third responsibility connected with the dratting ot messages is judicious 

use ot precedence. Time and again during the var high precedBnce messages, requiring the utmost speed were delayed by other meseages which had been assign- ed equally high precedence merely because the persons who dratted them thought their own messages the only really important messages being originated, and 

overlooked the need tor economical use or existing circuits. In one case, which 

caused w1des~read camment and brought vigorous action, a red-bot operational priority dispatch tram the Commander-in-Chief or the U.S. Pleet was delayed 6-1/2 hours and arrived too late to iterve its purpose. 'rbat same atternoon as 

it turned out, there were 110 other operational priority dispatches waiting to 

be transmitted, most ot them 'barel7 lukewarm. Subsequent investigation shoved 

that scarcely a dozen were or sutticient urgency to justify the precedence carried. Another case involving the misuse ot precedence occurred at and al'IQ' headquarters. A message with priority precedence came in addressed to tvo 

otticers vho were not at that headquarters. It vas necessary to go back to 

the originator in order to find out whether the message bad been addressed 

correctl7. "Sit on the message,• the originator replied. "lfhe tvo orticers 

are on their way and arrive in a couple ot days." 

In many cases a high precedence may be required tor the action addressee, but a lover degree will suttice tor 1ntormation addressees. It message drafters 

make a habit or asstgnins a lover precedence to 1nt'ormation addressees when 

practicable, communicationa will be able to function more rapidly when speed 

i• required. 

The tollOYing considerations are also of great 1m,portance in the intel-

-1.igent use or precedence: 

1. Precedence begins vh•' a ••saff is dratted. It is onl7 tair to 

expect originators and re easing o icers to hind.le it with the same 

8peed they expect of coaaunications. 

2. Precedence is a ~1de tor communication personnel. not addreHees. 

It ts b8tfer to askether the text alone ~•quires prompt action tii&n 

to insist on speed ot transmission, since high precedence gains speed on 

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JA'IP 143 

the circuits only and does n"t require prompt action on the part of' the 

addressee. ' 

3. !l'i zone d ere ea have an 

exa'lllJ) e. routine prece ence ma.7 too high or a vest ound message and 

too low tor an eastbound message. It ia not intelligent generalship nor 

admirable naval tactic• to aaaign a J)recedence Vhich result• in deliver7 

during the night vhen no action ia neceaaar7 until the tolloving morning· 

DOES I'! SAY WHAT YOU MiW'' 

Dratting the text vith completeness, clearneaa, and brevit7 i• never eaa7. 

Patience, practice, and resourcet'ulneaa are needed. The tirat try ia not likely 

to be aatiaf'actory unleaa the drafter haa had thorough. training and considerable experience. A dictated meaaage is almost certain to be wordy and theref'ore ver7 unmilitary If' it doesn't contain too many vorda, it probably contain• long, pompous ones which are out ot place in measage texta. 

Oofl!leteness ia the tirat requirement or a well dratted measage. If' it 

does no give all the necessary tacts, it may be little better than no message 

at all, especially when combat ia imminent or in progress 

Duri~ 1943 the enemy vaa able to sink one of' our ships and escape unharmed f'rom American waters because or incomplete meHagea and failure to aend 

a message at all. One plane reported the rescue ot survivors but tailed to 

give the time or position of the attack. or the course or the enemy submarine. 

Another neglected ta make an amplifying report. A third plane tailed to give the position ot the submarine or to eommunicate with a plane which vas in a 

position to assist; it also tailed to make adequate amplifying reports and used 

code Yhen speed was vital and plain language would have been or little value to 

the enemy Accuracy is also of' vital importance. Dovned·aviatora vere sometimes lost during the var because reporting planes in their eagerneH to hasten 

a rescue save incorrect positions. Later corrections did not always get through. 11umerous instance• could be cited. 

Olearneaa ia another major f'actor in meHage dratting. A meHage vhich 

does not say exactly what the originator intends to say or one vhich can be 

read vith tvo quite ditfel"8nt meaning• is likely to lead to conf'usio~ and 

disaster. Thia tact was torcef'ully stated in a CDCPAC-CDCPOA. report or 

operations in the Pacific: 

"A Uttle thought will ahov that the diapatchea one send.a may be 

more vitally important than anything else he is likely to do in 

the battle; and that however great the atreas of the aituation, 

one must apply to their contents and phrasing the same cool, calculating judgment that he vould use i-n spotting salvos. launching bombs or torpedoes, or maneuvering hi• ship or plane against the 

enemy. 

"Let us suppose (tor the empha•is of' compari•on only) that one or 

our ah1ps or planes should desert in the f'ace ot the enemy and seek 

safety in tligbt. or that its personnel ahould be so tluatered by 

danger as to be ineffectual in the battle. '!he vel"J' thought 1• 

abhorrent to ua; and yet it thi• thing ahould happen. the harm dons 

might not be aer1ou•. It would be only one unit tailing; and other• 

ot •terner atutr could be counted on to ma.ke up tor it. \ 

"But a single inaccurate or misleading diapatch, though dratted 

by •omeone or impeccable loJ"<y and courage. can ea.any vork tar 

greater bal'lll than the foregoing auppo•it1ous detection, since it 

ma.y be the cauH ot error or delay in the action taken, not •r•lJ' 

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by one plane or ship, but by v'hole groups or forces. Tb.us, trom 

the standpoint or the results, a rorce thirsting tor combat with 

the enemy, but hunting for him in the wrong place because ot a 

too-hastily worded dispatch may fail as badly as though it bad 

little stomach for fighting at all •••••••• " 

Lack of clearness affects communication sequrity as well as operational security in a very definite way Ir time permits, each addressee must ask 

for-clarification The resulting exchange or communications may not be completed during the day on which it began, and in wartime call sign ciphers or 

cryptosystems which change daily will be linked, thus facilitating compromise. 

CA'R IT BE MADE SBORTER'l 

Studies indicate that mes•ages can be clear and complete yet considerably shorter than the average military message now is. Here are five ways in which 

brevity can be achieved: 

1 Kill unnecessary amplifting details. Strike, search and intelligence reports were frequent offenders during the war. Only information 

of operational value was needed. Reconnaissance and situation reports from secondary areas were over-written 25--75-· 

2. Strike out superfluous words such as numbe~. following, and dated, 

before submitting a message for release, thus: 

As Sent 

reurser number Q81 

answers request contained in your urltr dated six July CNO dispatch 292359 June 

following items needed colon 

accomplish repairs 

to effect repair of 

Recommended 

REURSER 981 

ANSWER& YOUR 

URLTR SIX JULY 

CNO 292359 JUN 

NEED 

REPAIR 

TO REPAIR 

A submarine in the eastern Mediterranean in one instance used north 

and east 18 times in a single message. Neither word was needed more than 

once for clearness 

3 Use shorter words and phrases. Request expressions are among the worst.offenders For cryptosecurity as well as brevity the following substitutions are preferable: 

As Sent 

Request reply • 

Request following items 

Request shipment five spares 

Recommended 

ANSWER 

SEND 

SHIP FIVE SPARES 

In all such expressions please is understood. 

Savins 

§~ 44" 

Report and advise are two other words, which, like request, occur too 

often. Advise earliest practicable sh~iBl!date might well be replaced with the simple question HOW' SOON CAI Y b. 

4. Use authorized abbreviations. They are well known, and their use 

saves time and trouble. 'When an abbreviation ts very short and a garble of one or two letters of the abbreviation may be represented by their 

phonetic vords--unless the word itself is shorter than the phonetics tor 

its abbreviation. A/C apart from identifying words might give trouble, 

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but ABLE SLAM CHARLIE is twice as long as AIRCRAFT. 

5. Avoid unneceaaar~ use ot phonetics. They only waste space in 

expressions like 'Oitcil S GAR Miki5 CHARLll, but they serve a useful purpose in LOVE SUGAR 'l'ARE when used apart tram the mme, number, or ot)lE. r iden-

• titica tion. The tallowing is an extreme example ot phonetics gone beserk, 

all or the expreseions having appeared in a single message ot medium 

length I 

CHARLIE OBOE MIKE DOG TARE NAB YOKE DOG tor COMM! IYD 

SUGAR OBOE BAB YOKE DOG tor SUPOF NYD 

OBCLB ROGER SUGAR SLA.B~ ROGER apparently tor URSER 

ROGER YOKE EASY XRAY PETER BAXER SLANT LOVE apparently tor 

RAIUIAY EXPRESS BLA.DINO 

I'l'BM BAN VICTOR apparently intended to mean INVEBTORY 

Thia little orgy lengthened the meBBage by lB groups or about 2~, 

and the message would have been 10 groups shorter than it was it all 

ot these words had been tullY spelled. 

Other useful ways or achieving brevity include the deletion or unnece11sar7 

punctuation. Telegraphic style has amall place tor it, and its use should be 

severely limited. Combining reports is another important way to reduce traffic. 

Fuel and ammunition reports tor example, may serve their purpose equally well 

it required leas treqnently. • 

DON 'T QUOTE 

Quotations trom another message or almost any other source are a security hazard The danger is much greater with some cryptosyatema than others, but 

an originator has no way or kn.owing which cryptosyatem will be used. The rule 

ls therefore very simple: restate in different words it necessary, but ~ 

verbatim quotations. 

WAT ABOUT 'l'HAT REFERENCE~ 

References are security hazards it they appear too otten at the beginning 

ot a message They should be buried in the text. Plain language references 

to encrypted messages are dangerous in that they often reveal the subject ot 

referenced messages Fo~ this reason plain language references to encrypted 

messages are limited to those which consist ot the date-time group reference 

plus one or more ot the following words - Affirmative, Negative, Interrogatory, Comply, or Letter 

DOES IT AFFECT THE 'RATIONAL SECURITY'? 

The final responsibility or the drafter, once he haa assigned a reasonable 

precedence and dratted the text securelt is to classify reali•tically Overclaaaitication on a large acale undermines reapect tor the higher classifications, overloads the secret keys to cryptoayatems, and encourages laxity in 

handling and safeguarding documents and the information they contain. Underclaasitication is dangerous but much less common. Frequent reference to the 

definitions ot Top Secret, Secret, Confidential, and Restricted in ArlllJ' or 

Bavy Regulations will help all drafters of messages to find the happy medium 

between underclaasification and overclaasitication 

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CHAPTER III 

COMMUBICA'l'ION SECURI'l'Y IR PEACE'l'IME 

'l'he continuing iDQ>ortance ot communication eecurit7 cannot be overemphaeized. Since the cee1ation of hoetilitie• a large volum.e ot ola••itied 

intormation ha• been downgraded; however, a tremendou• amount ot intOrmation 

remain• claeeitied and or vital intereet to the national •ecurit7, alld i• 

constantl7 being added to bJ' current development•. In addition, potential enemies will have more leisure in which to attempt penetratian ot our 1ecurit1 

barriers. 

It is essential that the elements et communication eecurit1 be understood 

and provided tor at all levels. Thoaa vbo uaa the communication aervice must 

learn and practiee the dratting ot clear, complete, concise meseage1, and 

aseign realistic clas1itications and precedences. Physical secur~tJ muet be 

considered. Ettort• to eteal, copy, photograph, or otherviee obtain cipher keys and specification• ot our cryptographic equipment are not likely to 

4Sminieh during peacetime. MatlJ' ot our cipher• will be le•• expoeed to capture, but infiltration ot ene111 agents may actually be tacilitated bJ" the un1uepecttng nature of Americana. Security ot thought, word, and action are requiaitee. Public places and desk telephones do not provide th~ secure conditions neceseary to~ the diecuaaion ot top secret matters by high-ranking officers or other•. 

aecurity ia one ot a comma.nder•• beat deteneive weapons. It i• alao one 

ot his prime reeponaibilitiea 'l'he eucceeatul otticer will know the rules and 

procedures de•igned to provide •ecurity, ana he will follow them. 

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