JANP 143 

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REF ID:A71. 

COMMUNICATION SECURITY 

Published by the authority of the 

JOINT COMMUNICATIONS BOA.RD 

Washington 25, D. C. 

April 1947 

FIRST EDITION (7 APRIL 1947) 

I 

fU!lSi'fUBHB 

NON-liEGISTERED 

Declassified and approved for release by NSA on 09-20-2013 pursuantto E .0. 1352a 
~ I ~ 

1\!15 fRIC'lib:lJ 

Joint Communications Board 

• REF ID:A71913 

THE JOINT CHIEFS OF STAFF 

Washington 25, D. C. 

COMMUNICATION' SECURITY 

(Short Title: JANP 143) 

1. This publication i8 effective on receipt. 

JA'Nl> 143 

?. JANP 14~ is a restricted non-registered publication and shall be safeguarded in accordance with current instructions for the safeguarding of 

restricted documents. Periodic accounting is not required. 

3. JANP 143 may not be carried in Aircraft for use therein. 

4. Approved in principle by the Joint Deputy Chief's of' Staff' and published by the authority of' the 

JOINT COMMUNICATION'S BOARD 

Washington 25, D. C. 

April 1947 

E. H. PIERCE 

Captain, U.S. Navy 

GERALD CARLISLE 

Lt. Col., Sig. C. U.S. Army 

JOIN'!' SECRETARIAT 

"This document contains inf'ol'ID&tion affecting the national defens£ of 

the United States within the meaning of the Espionage Act, 5¢ U. s. C., 

11 and 32, a.8 amended. Its transmission or the revelation of its contcmts 

in any manner to an unauthorized pel'son is prohibited by law." 

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IECOID OF CQllECTIOIS 

Change. Dispatch. Letter or 'He1110rand11111 10. Date By whom entered (signature. rank or rate. name of connand) . 

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JANP 143 

INTRODUCTION 

Intelligence is an offensive weapon, one which :1earches 

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

strong points again and agatn, until they, too, are rnade weak. 

The only defense against intelligence is security and no form 

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

In the words of Frederick the Great, "Ir one coJ.ld always 

be acquainted with the enem7.'s designs one would always beat 

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

more recent vintage, a prisoner of the past war, "I.f U. S. 

troops win the war it will be in spite of their communication 

security and not because of it." 

The establishment a~d maintenance of communications 

security is a function of command, a function that unfor- tu~ately is not always understood, not always correctly per- formed. This pampblet will attempt to bring home to all officers 

their past deficiencies in comm'..lnication security and the steps reco:nmended to correct them. 

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JABP 143 

CHAPTER I 

THE COMMANDER 1S RESPOl'lSIBILITY--COMMUNICATIOB SECURilfY 

Every commander, regardless or echelon, must be vitally concerned vith 

security in all its phases, for every commander is constantly receiving and 

disseminating classified inf'ormation. Without a secure communication system the commanding officer ot a modern armed force cannot safely transmit inf'orma.tion to, or receive inf'ormation from, collllllBnders of other units. 

The measures that a commanding officer employs to prevent compromise of the traffic handled by the systems of his unit constitute communjcation security. Bis responsibility in this regard is shared to a certain degree by his cryptosecuritY. and communication officers but because or the highly important relation of security to tactics, the commanding officer himself 

has the final responsibility. 

SECURITY IN STAFF WORK 

Communication security is definitely an item for staff conside1•ation 

and understanding. The comma.ndel' should take communication problem~1 into 

the conf'erence rooms as an operational part of command. He should l•equire his security personnel to make periodic reports of how much inf'orma~ion bas 

been exposed to the enemy. This inf'ormation should be considered vh.en ma.king mili~ary decisions. The status of security of communications should be coordinated with various staff sections, particu~rly operations. 

It is obviously adverse diplomacy for a junior officer to tell his senior 

officer what he can, can't or must do. However, it is the duty of the junior (staff officer) so to inform his superior (commander) regarding com:nunication 

security that the commander decides and acts with knowledge and not in ignorance of risks involved. Completed staff action in this case is a detinite 

"must," and the commander should demand it. 

The final responsibility of command for communication securitJ cannot 

be delegated. However, it is an unwise commander who attempts to do all the 

work of his staff. Regulations permit him to appoint an officer of his staff 

as the security officer, cryptosecurity officer, Top Secret control officer, 

or communication security officer. This officer then is responsible to his 

commander for the execution of his appointed task. The importance or his job 

cannot be overemphasized. Perhaps the most important job of an officer in this 

position is that Of cryptosecurity. Actual examples Of insecure CI>yptographic practices point out the necessity for strict control of means of cc>mmunication. 

1. Failure to Reeort Loss of Codes or Ciphers 

Por eight days· a military code was used after it had fallc'n into 

the hands of the enemy, because compromise was not reported i111mediately, . as required by instructions. Fortunately, it was a special-purpose code 

not ordinarily used for secret traffic, but the damage might have been 

very great. There is no way of knowing how great it actually was. 

2. Discretion in Destruction 

A naval vessel was engaged in a running battle with enemy craft in 

the English Ch&nnel. Considering the relative position of ship, enemy, 

the rocky French coast, and other circumstances, the couunanding officer d~cided that to jettison the registered publications was a necessary 

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precaution. When the order to jettison was given, one sack or pub- lications landed on a submerged rock. The sack broke open and a swift 

tide scattered the publications far and wide. Subsequently, many of the 

publications vere recovered through the efforts or other naval vessels. 

Some were picked up by French fishing vessels, others were found along the shore. Some were never found and supersession of many publications 

was necessary. While it is difficult to criticize acts committed under 

such ci~cumstances, it must be pointed out that both instructions and 

good judgment require that jettisoning be done in deep waters. Had the 

publications been put over the side earlier, considerable inconvenience 

to allied communications and the expense of replacement of compromised publications might well have been avoided. 

3. Use of Superseded Publications 

Because a superseded code was used to transmit a warning, an Army bomber group in the China-Burma-India Theater nearly came to disaster 

during the war. The group was on its way toward Kyushu in Japan and 

had been gone about two hours when the Navy reported a sudden hurricane 

off the Japanese coast. All fields were ordered to establish comm.uniction with their planes and change the target to Shanghai. Each base 

notified its planes without incident except for one base, which encrypted the hurricane message in an obsolete code. The planes operating from 

that base copied the message readily enough, but reported that they could 

not decrypt it. The crypto officer at the base was not in the cryptoroom, and the nature of the difficulty could not be determined at once. 

By the time the message had been encrypted correctly it was too late. 

The planes were beyond the range of communication. Unwarned, they rode 

into the hurricane, narrowly escaped destruction, and had barely enough fuel to return to a China base. By just one error in the use of a cryptosystem the lives of 300 airmen were thus jeopardized and the efforts of 

2,000 men expended uselessly. 

4. Loose Handling of SOI•S 

Two bombers crashed into the sea while on a training flight. Each 

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

result, the SOI•s issued by the bomber command were compromised for a 

period of several days. 

A pilot returning from a training flight discovered that a portion of an SOI folder was missing. The radio operator was of the opinion that the portion was not in the folder when it was handed to him. However, it was necessary to report that the missing SOI possibly had been 

compromised, since no check of the contents of the folder had been made 

prior to the flight by the issuing officer or the operator. 

Certain signal operation instructions contain information of extreme 

importance to the enemy. Therefore, crew members on tactical flights are 

permitted to carry ONLY those extracts or SOI•s which are necessary for 

pursuance of ilJlDlediate tactic.al operations. Precautions which are necessary for tactical flights should be observed during the training period and conmia.nders must assure a realistic approach to all security practices during training exercises. 

5. Use or Unapproved Codes and Ciphers 

It is an obvious truth that precautions must be ~bserved in considering plans for operations. Without security it would be impossible to 

achieve surprise in attack. Codes and ciphers are furnished to a commander so he can achieve surprise and cortrol his forces, without his 

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intentions being known to the enemy or to those parts of his own forces 

which should not know future operations. The pressure of war may force 

us to use less secure cryptographic systems. The commander therefore 

should be aware of the weaknesses in those systems upon which he may be 

forced to rely. He should prevent the use of locally produced C'l."yJ>to- graphic schemes. Nothing can lead to more trouble than relying on a 

crypto-aid which cannot stand before an enemy expert. Only approved codes should be used within the services. 

SECURITY IN THE USE OF MEANS OF TRANSMISSION 

Because commanders are forced for the most part to rely on electrical 

communications to effect the dissemination and receiving of classified information it will be well to determine just how private these means are in 

order that the information which has been encrypted, and even the cryptosystems themselves, may accomplish the desired purpose and not become ineffective through disclosure or compromise. 

Wire transmission is rightly considered to more secure than radio, but 

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

wire lines are free from interception. 

Interception on wire lines is a frequent and important source of intelligence. Wire tapping often may be discovered through physical examination or from transmission irregularities, but interception by induction can 

escape detection completely. A supposedly secure communication circuit of a 

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

of wire placed as far as six feet from the communication line -- even if the 

six feet consist of reinforced concrete. 

During the war the Germans consistently used many clever tricks to 

intercept communications and to conceal the fact that interception was going 

on. They placed carefully hidden taps on wire lines which they were abandoning and which they knew advancing Allied troops would use for their own 

communications. In one instance the Russians found a communication system in 

splendid condition in a village evacuated by the Germans, but careful examination showed that something had been added. A buried cable extended from 

each end of the village circuit. They learned later that the Germans had 

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

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

electrical communication has had a profound effect upon communication security. The speed, range, and versatility of radio have kept communications apace with the mobility of modern warfare. But the use of radio has also exposed communications to their greatest danger--radio transmissions can be intercepted by friend, neutral, and foe alike. The mere fact that a radio station 

is· on the air is a source of information to the enemy. The extensive use or 

intercept stations and direction finders enables the enemy to record every transmission that is made and to log the place of its origin, thereby gi~ing 

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

A single electrical impulse may indicate the existence of a unit. Upon 

one occasion during the North African campaign, several aircraft were sent on 

a mission and every precaution had been taken to conceal 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 remainder of the operators in the flight eagerly entered into the ugame, 11 

each adding a "di t" to his response. All previous efforts to conceal the 

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flight were lost since this "harmless" ga.me disclosed to the listening enemy the exact number of' aircraft in flight without a message being sent. ~ 

mission was unsuccessful and serious losses resulted. 

LOCATIOH BY RADIO 

Direction finding today is more erf'ective than many of'f'icers realize. 

Although radio silerice can be carried too f'ar, it has lost none or its importance. Tests or captured equipment show that it is possible at a distance or 

100 miles to locate accurately by direction finding a 50 watt VHF transmitter. 

Forward observers and naval gunfire liaison of'f'icers reported that the Germans 

possessed ef'f'ective D/F equipment and were able to locate key radio stations 

and subject them to f'ire in a matter of' seconds, according to an of'f'icial 

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

radios until after German batteries had been driven out of' range. 

In the North African campaign, a U.S. tank destroyer battalion was moving into postion to attack, and radio silence was ordered. After several hours, 

a detachment from the battalion realized it was lost and broke radio silence 

to verify its position. That enemy direction finders were on the alert is 

evidenced by the f'act that a subsequent air attack wiped out the entire detachment. 

Naval vessels also suffered as a result of' 111-advised use of' radio. 

Over-use of radio was given as one reason for the loss of' ten Allied submarines in the Mediterranean during the early months of' the war against Ital,;. 

PT boats were often bombed by float pla.nes immediately after radio transmissions although the planes had previously passed overhead several times 

without attacking. Submarines operating in the Paci.fie noticed on several 

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

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

to both aircl'af't and surface interception within 17 hours. "Numerous close 

Jap radio stations seemed to D/F the submarines quite accurately,, '

1 one report declared. 

A vessel in the ~ul'opean ~heater broke raa10 silence to report a rudder 

casualty. This report cou1a have been c1eared later by visual methods. In 

another case, radio silence was bl'oken to report a small hole in the ship's aide, well above the waterline, the sea being quite calm at the time. The 

operation plan specifically stated that strict radio silence ~as to be maintained and that submarine and other enemy contacts were to be reported by visual methods. 

Under some circumstances radio silence may be less important f'or planea than for surface ships. Failure to observe radio silence, however, may disclose a flight which vould otherwise surprise the enemy, and insure fol' 

the planes a deadlier l'eception while performing their mission than they would otherwise encounter. 

RATIONALIZING RADIO SILENCE 

Although it is one of the most effective components of communication 

security, l'adio silence can be carried to the point whel'e it becomes a handicap rather than a protection. When it is l'easonable to assume that the enemy is .unaware of' the presence Ol' precise location of a task f'ol'ce or ship and 

does not anticipate the opel'ation which is about to commence, the breaking of 

radio silence must be ordered only as a calculated risk. However, when it is 

certain that the enemy knows the locatjon or anticipates the movements 

of' a ship or task force, or when contact bas been made, there is little to 

gain by l'adio silence. Dispensing with fighter direction in order to pl'eserve radio silence was given officially as one of the factors contl'ibutine 

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to the loss or a United States cruiser early in the war. Observance •)f' radio 

silence upon the occasion of a positive enemy contact shows a lack of' appreciation of the off'ensive action expected or units of the fleet and jeopardizes the safety or all other units in the vicinity. 

A JAPANESE COMMENT 

Eloquent testimonv on the subject of radio silence was offered in a 

Japanese broadcast beamed to the United States from Batavia in the Netherlands 

East Indies during the war. It read in par~ as follows: 

"If the Americans are so eager to fight the Japanese Navy, why do 

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

the ~apanese Navy will come out and meet them? If' one may believe the 

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

there. Notwithstanding the fact there were only small units of the 

Japanese fleet, and notwithstanding the fact 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 of' Japanese forces in Truk:." 

SUCCESSES OF JAPANESE INTELLIGENCE 

Interrogation or Japanese intelligence officers brought to light. a 

number of useful facts about the nature, extent, and success of enemy efforts 

in the field of' communication intelligence, especially traffic analysis. One 

of the officers was Commander Hideo Ozawa and the other was Lt. Comd1•. T. 

Satake. Both held key posts in the radio intelligence section of tho Japanese Naval General Staff during most or the var. 

Owada was the center of' the activity described by Ozawa and Satnke. Here 

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

were seven of these areas--the vest coast or the United States, the Indian 

Ocean, and five different sectors of the Pacific. Several officers ·1ere assig- ned to ea.ch area.. 

Traffic was analyzed according to call signs, cryptosystems, pl..iin language, tota1 volume, procedure signals, and precedence. Volume and pre- cedence were plotted on a chart, one for each area. Though usually 11nable to 

decide wiiether transmissions came from ships or shore stations, enemy analysts used direction finders to determine the point of origin. 

United States operators were often identified by individual peculiarities in sending. As a rule ships could not be tra01:td, however, presumably ~eca.use 

rsdio silence prevailed quite generally. The enemy analysts were not able to 

estimate the strength or our forces in various theaters. If a. force broke 

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

It was realized that a peak in traffic represented ·"a crisis." The 

interpretation "was completely· dependent upon the tactical situation," 

however, and the Owa.da officers "could not tell where that crisis would 

materialize." 

Taki~ Okinawa. as an example, Satake ~de a statement translated as 

follows: A month before Okinawa, BAMS***\Rad1o Broadcast) had a notable· 

increase in transmissions. Ten days before the Okinawa operation, there was 

a marked increase in submarine reports. These are easy to spot because we 

got good direction-finder fixes as they are close in. When submarines changed from routine operational communications to urgent, we deduoed that r•erhaps an 

air strike or landing might be in the offing, depending on the tacttcal 

situation." ' 

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Ozawa, when asked what was the greatest success ot naval radio intelli·· g~nce in predicting future operations, named the Marsh&lls operation. "We 

got the word to the garrisons in time to be or some help that they should 

prepare ror an attack," he stated. Regarding the basis of the prediction, he explained as follows: "Bombing grew intense. Both ship and aircraft 

volume or radio transmissions rose to a peak, and we were able to pick up a 

f'ew plain-language broadcasts. I remember one saying General Olds would 

arrive shortly. 11 Aside f'rom "some minor success in predicting the Iwo Jima 

landing," Ozawa claimed little or no success in other operations. 

Air-to-air and air-to-ground coded information lol'aS received and "we were 

able to interpret much or it," but "the rapidity with which aircraft codes 

were changed caused contusion to us," Ozawa stated. Our aircraft of'ten gave 

away our plans. 'When B-29s prepared to take of'f' "there was much adjusting of radio frequencies." Moreover, "weather reconnaissance planes which pre· ceded large strikes gave an indication or the large strike by the volume of' 

data sent back to its base." Ozawa CJ.aimed 50 percent success in making predications based on weather reconnaissance flights. 

It may hav'e been due largely to our def'ensive measures against traf'f'i4' 

analysis and also against interception and direction finding that the enem.r 

did not learn more and was seldom certain of' the deductions that he f'elt 

justified in ma.king. 

USE OF RA.DIOTEU!:PHO~E 

In this treatment of' radio security a particular and separate emphasis 

must be placed on the proper use of' radiotelephone. During the second world 

var its incorrect usage constituted one or the most vulnerable spots in the 

security armor or communications. Too much emphasis cannot be p1aeed on t.he 

need f'or extreme security consciousness in the use or radiotelephone, f'or the 

:tact that such equipment can be operated by other th.an trained personnel increases the need for adequate control and complicates the problems or good circuit discipline, correct procedure and strict adherence to all securit:r 

precautions. 

The security of' voice codes is comparatively limited even though they 

are prepared by experts and of'fically approved. This is due to the necessity f'or simplicity. However, the outstanding difficulty encountered in the 

security of voice codes can be attributed chiefly to the so-called private organizational codes. This was clearly demonstrated in operations in Sicily and Italy. lnf'o:MD&tion obtained from prisoners indicated that the Germa~s 

wer~ usually able to figtire out these private codes rather easily. Veiled 

language is scarcely more dif'f'icult for the enemy to understand than for the 

person being addressed. 

Use of' a foreign language does not provide any measure or security f~s a 

rule, although U.S. forces are said to have used Choctaw and Navajo IndicLns 

as telephone talkers quite successfully. The British used Latin as a makeshift during the Boer War because they knew the Boers were not familiar ,.,ith 

it, but the Boers would certainly have round someone who was if the British 

had depended on Latin very long. 

The mistaken idea that voice radio transmissions are more secure than 

keyed transm1ssions is one of' the most treacherous illusions in the fiald of 

electronic communication. The insecurity of VHF transmissions was not gener- ally realized during the early years of the war. This fact explains in part the tendency to use voice radio circuits too much and to transmit intorrration 

which should not have gone out on the air, even in a voice code. In 19~5 a 

headquarters ship on a tvn-week voyage from Iwo Jima. to Pearl Harbor wae able 

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to log each day VHF transmissions f'rom Iwo, the Ryukyus, or the Philippines f'or several hours a day until the day before it arrived. The maximum range 

at which solid signals were picked up was 3700 miles. The more a com10anding of'f'icer knows about radio wave propagation at various frequencies, the more 

discreet and judicious he is likely to be in his use of' voice radio. His 1s 

the direct responsibility f'or its secure use. 

VHF, UHF, and SHF designate s~cif'ic bands of' "v~ry high," "ultra. high" and "super high" frequencies (30,000 to 30,000,000 kc} which are e~loyed 

f'o~ the very reason that their normal range is limited rou~ly to "line of' 

sight." Instances continue to accumulate, however, of' verified reception 

at distances of' several thousand miles. Thus, even though higher frequency bands normally provide more limited range characteristics than the lower 

f'requencies, they are not secure enough to justify use of' plain language which on lower frequencies would have to be encrypted. Voice transmissions 

on any f'requency are, in reality, less secure than CW on the same frequency because anyone can understand them--without knowing the telegraphic code. 

Carelessness on VHF leads to carelessness on MF and HF voice circuits. 

The fact that radio is the least secure of' the means used f'or transmitting messages makes it necessary f'or anyone using radiotelephone to be 

thoroughly versed in radio procedure. Radio procedure is formulated to 

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

a brief', def'ini te and uniform language. In the interests of' security·, no 

variations, elaborations or "short cuts on the prescribed procedure should be 

authorized. 

In order to prevent the enemy f'rom gaining much information fro~ his 

observation of' radio activity, the principles of' radio security have been 

developed. These principles e:re grouped into f'nur categories: Disc:lpline, Silence, Deception and Interference. 

RADIO DISCIPLINE 

Radio transmission security embodies the maintenance of' circuit discipline and the suppression of' all superfluous transmissions. That component of' radio 

transmission security which includes the maintenance and proper use of' radio 

equipment, the adherence to prescribed procedure when operating and t.he 

employment of' remedial action when and where necessary by the net control 

station or other responsible agency is known as circuit or radio discipline. Co?'rective measures taken ta,,ard the suppression of' excessive transm:l.ssions 

are f'ormuiated on the basis of' procedure analysis of' monitored mater1.al. 

Security monitoring logs are analyzed for deviations from prescribed pro- cedure to determine trends in violations. Analyses indicate the nature and 

extent of' corrective action to be taken within the units concerned. Radio 

transmission security is attained by the following: 

1. Training radio operators in the principles of' cit'cuit discipline. 

?. Monitoring transmissions of' our forces. 

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

necessa.ry. 

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

includes active imagination on the part of' anyone using radiotelephone in 

order to deny all information to the enemy which may help him analyzE~ the 

message intercepted. It should be impressed that continued alertnes15 must 

be the watchword of' all communication personnel. It was an alert German 

ope:rator who noted, during the f'irst world war, that the shore stati1>n at 

Scapa Flow broadcast weather reports only when Grand Fleet units wer43 at sea. 

lie thus could advise the German Admiralty when British ships left th•!lir base. 

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'RBB'fft!G fED 

There are basic rules that should be remembered and followed by anyone using radiotelephone. While these rules and many more should be instilled in 

trained radio operators, these should be or particular concern to the officer 

who, on occasion, used radiotelephone. 

1. LISTEN BEFORE SPEAXIWG. Failure to do this causes loss or time and 

makes additional transmissions necessary. 

2. SPEAK CLEARLY. Clipped speech and..fammed-together words are difficult 

to understand. 

3. SPEAK SLOWLY. Must be slow enougb to be copied without "repeats." 

4. SPEAK EVENLY. Not in a monotone. 

5. KEEP THE DISTANCE FROM MOUTH TO MIKE THE SAME AT ALL TIMES. Inexperienced pe~~onnel often fail to realize the importance of this detail • . 6. MAINTAIN A NATURAL RHYTHM. Group words and phrases in a normal 

manner. Transmit phrase by phrase, not word by word, avoiding "er•s" and 

"ah 's." 

7. USE STANDARD PRONUNCIATION. Standard speech without sectional 

peculiarities is most easily understood. I 

8. "KEEP !l'RANSMISSION TO A MINIMUM. Avoid crowding circuits with exces,1-

ive call-ups, receipts, tuning, testing, and unnecessary repetitions. 

9. USE STA'RDARD PHRASEOLOGY. Continuea use has made its meanings unmistakable. Nicknames and fancy language are conrusing and leas brief. 

10. INCLUDE SUFFICIENT INFORMATION. Messages omitting necessary information are worthless. 

11. DO NOT COMPROMISE VOICE CODES •. Never state in plain language what 

ha.a just been transmitted in voice code. 

12. USE PIAIN IA'NGUAGE WITH THE GREATEST DISCRETION. Fu:bure operations have sometimes been discussed on voice circuits. An instance at Tarawa gavo 

the enemy advance warning of landings planned at other points subsequent to 

the initial landing. 

13. DEMAND AUTHENTICATION WHENEVER THERE IS CAUSE FOR SUSPICION. Do not 

allow enemy attempts at deception to succeed. He can speak excellent English when the need arises. 

SILENCE 

As stated previously, radio silence is the primary defense against interception and direction finding. Both interception and direction finding 

are now effeotive on nearly all frequencies. A transmission of only a few 

seconds duration is sometimes sufficient for obtaining a bearing. Avoid all 

unauthorized transmissions and unnecessary testing. 

DECEPTI<m 

Although adaptable to any means of communication, deception is employ1:td chiefly in connection with radio. There have been many instances in which 

the enemy has attempted to disrupt communications to prevent a message fro·n 

being delivered, divert our forces or draw them jnto a trap. Enemy methods 

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include an~wering call-ups and ottering to accept traffic, receipting ror 

mel!IBagea which our stations have not been able to copy, transmitting r.ilse orde~s by voice or radiotelegraph in plain language and originating messages pieced together rrom parts or intercepted messages. 

The greatest defense against enemy attempts at deception is the correct 

usP. or authentication. Incorrect authentication undermines communications and 

invites deception, especially in combat when seconds count. Even an occasional 

error tar trom the scene of action is a serious matter. It delays traffic and e~courages operators to distrust or disregard an important means or protection. A vital message may be disregarded. 

An incident illustrates quite clearly what could happen in actual combat: 

uDuring maneuvers, the artillery in a Blue division dropped the use of authenticators. The radio operator or a Red division passed himself off as the Blue 

net-control station. He received iocation or units, p!ans or tire, ar.d future 

movements; he directed tire into an empty field and along an unoccup1ed ridge; he persuaded the receiving operator to ignore the fralll>ic calla of the real 

net-control station, and finally created so much contusion and mutual distrust 

among the Blue stations that radio communications broke down completely." Unless radio operators are thoroughly instructed and well-trained in the use 

or authenticators THEY WILL MAKE MISTAKES. In order not to forget about 

authenticators it is necessary to review instructions and PRACTICE thE=·m. 

Japanese deceptive ingenuity in obtaining inf'ormation from AAF r&dio 

operators was revealed by reports from the Central Pacific. A B-29 which ~rticipated in a mission over Japan gave its altitude, course and sp(1ed in 

response to a radio query, apparently from a plane that had become de1;ached 

.rrom the formation. Immediately the foz'mation experienced intense ancl accurate 

antiaircraft fire. This could have been avoided by proper authentica1;ion. 

Another B-29 on a later mission, in reply to a similar query, gave ~nnccurate 

information with the result that antiaircraft tire became "intense anti accurate" 

at an altitude far below the B-29 formation. 

Appro~riate training manuals contain measures designed to prevent enemy interference from succeeding. Listed below are some or the more impo~tant 

ones to be re~~mbered by commanding officers as well as radio operato~s. 

1. Improve procedure and circuit discipline. These should attain such 

perfection as to nulliry any attempt by an enemy to imitate procedure. 

?. Demand authentication whenever there is call tor suspicion. Plain 

language is more vulnerable to deception than encrypted traffic. A 

request for authentication will usually expose and silence the most 

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

to authenticate PROMPTLY AND ACCURATELY. 

3. lteep accurate logs. These will be useful in studying suspicious transmissions. Much can be learned from them. 

4. Do not reveal the precedence of messages awaiting transmission it 

this can be avoided. Doing this may invite interference if the pre- cedence is high. The enemy may try to accept the message, receipt for 

it or jam the transmission if all else fails. 

5. lteep procedure messages and service messages at a minimum. These 

help the en.811lJ' to learn our procedure and meanings or operating signals, thus making imitation comparatively easy. 

6. Respond promptly on call-ups. 

em.emy to come ~n on a circuit. 

I Long call-ups are an invitation to the 

7. Report' all irregularities at once. This may help in discovering 

Or:!ginal 

9 
REF ID:A71913 

JANP 14? 

vbttthcp" 'tb:.e 1nterf'er1ng station la genuine or not. If' it 1a not, th'l..a la!gli~ ._1so help destroy it. ·• "'~.BIUl .. '.i: " -~ ' 

-, "During the Tarawa operation, a Japanese opera.tor took over the 

the call of' the commander of' one of' the transport divisions and . and gave orders to land troops and supplies to the westward of' a 1 - .certain pier. The position or Jap automatic weapons at that timo 

was auch that this was the worst place to land. '!'he operator vats 

a1ert and auspicious. He demanded authentication. When this wa.1 

not forthcoming, an urgent waa broadcast to disregard thia deception and the Jap attempt f'ailed. This illustrates the necessity f'or 

constant use of' authenticators during such periods." ,,. 

8. In re~rd to radiotelephone, remember the two basic assumptions ·i:;hat 

must always be considered whenever radiotelephone or wire circuits ai•e 

used. 

a. All 1;elephone calls over a circuit which has a radio link 

vip be heard by the enemy. 

' b. All telephone calls over wire circuits may be beard by the 

e:nelDJ'. 

"A telephone circuit which had a radio link was monitored for th~ee 

hours. :Headquarters Third U. S. ArlDJ' disclosed that during this brief' 

period auf'f'icient material was provided •to enable friendly monitors to 

establish a f'airly complete personality f'ile f'or this headquarters, almost the complete order of' battle f'or our higher echelons, and the 

exact coordinates of' this headquarters advance command post one day prior to its opening.•" 

Having treated.the command functions in regard to signal security it 

would be well now to turn to the originator and determine his position in the 

o1'8r-all pattern of' secure and ef'f'icient communications. 

" 

r r ' 

0r1s1m1 

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REF ID:A719. - JA'NP 143 

CHAPTER II 

THE ORIGINATOR AND COMMUNICATION SECURITY 

The mission of a military communication service is to provide reliable, 

rapid and secure communication to command. The most direct, and often the 

only, contact that many officers have with communications is in the capacity of originators or addressees of messages. It is essential that those who use 

this service are aware or and observe the relatively rew be.sic rules which will 

assist materially in the accomplishment of this mission. 

Messages which make the grade on security counts will usually be round ~atisfactory by any other communication standard. Communication security begins with the originator. His skill in drafting a classified message has 

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

the sec-rets of brevity, his message will take less time to encrypt, t.ransmit, 

and decrypt. The net result of similar skil1 on the part of all originators will make a surprising improvement in the speed with which messages e.re transmitted and delivered. Clearness and exactness also pay dividends. A message whicli is not clear causes misunderstanding or necessitates a service message. If the messages are classified, security suffers, and in any case tho over-a11 

speed or communications is reduced proportionately. 

,MUST IT GO BY RADIO? 

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

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

originator is to specify another but more secure means of communication than 

electrical whenever circumstances permit. 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 field 

in preference to electrical communication whenever practicable. At sea he 

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

capacity at his disposal, at least in the United States; or he may nmploy guard mail or air courier services and sometimes diplomatic pouch if he ia in a 

foreign country. 

U.S. mail service frequently equals the speed of' a low precedence message. In continental United States no two points are more than a day apart for mail 

planes, and the U.S. postal system is sufficiently secure for most confidential 

and secret communications. 

Betore using radio or any other electrical means of communication, therefore, an originator should invariably ask himself, "tsn•t there some other way of' getting this message to the addressees which will serve just as well and is 

at the same time more secure?" Sometimes methods other than radio .are raster. 

This has been the'""'CiBe with visual methods more than once during landing operations, and the same has proved true for mail plane service in advanced 

areas as well as in the United States. 

WHO WEEDS TO XNOW? 

The second responsibility of' all who draft or release messages is to 

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

tbe beading unduly, and often make it necessary to relay a message on more 

Original 

11 
REF ID:A71913 e 

RES'l'R1CTE1' JANP 143 

circuits than would othel'Wise be required. Sometimes a more widely held and 

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

Failure to include an addressee who needs the inf"orma.tion a message contains can be pQtent1ally more harmf'ul to security, however, than unnecessary addressees. The reason ls that it may be necessary to re-encrypt the message in a di.ff'erent cipher fol' an addressee vhom someone thought of too late. The 

dangers of' re-encryption are vell known. Any pl'ogress an enemy may have ma.de 

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

The tende.ncy toward including too many addressees is international. The. 

following statement vas found in 1944 in the notebook of a. Japanese officer: 

"The purposeless designation of addressees on a grand scale complicates the qxchange of communications and leads to an increase in 

the numl;>er of messages." 

Truer wQrds were never spoken. Here again it is the originator to a large degree who determines the speed and efficiency of his servant. the communication 

system. 

HOW SOOK MUST IT BE ACTED OH? 

A th1.rd responsibility connected with the drafting of' messages is judiclous 

use or _precedence. Time and again during the war high precedP.nce messages, requiring the utmost speed were delayed by other messages which had been assign- ed equally high precedence merely because the persons who drafted them thought their own messages the only really important messages being origins.tad, and 

overlooked the need for economical use of' existing circuits. In one case, which 

caused widespread comment and brought vigorous action, a red-hot operational priority dispatch from the Commander-in-Chief' of' the U.S. Fleet was delayed 6-1/2 hours and arrived too late to $erve its purpose. That same afternoon es 

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

be transmitted, most o'f them barely lukewarm. Subsequent investigation shoved 

that scarcely a dozen were of suf'ricient urgency to justify the precedence carried. Another case involv1.ng the misuse or precedence occurred at and army headquarters. A message with priority precedence came in addressed to two 

officers who were not at that headquarters. It was necessary to go back to 

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

correctly. "Sit on the message." the originator repl1.ed. "The two officers 

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

In many cases a high precedence may be required for the action addressee, 

but a lower degree will suffice tor information addressees. If' message drafters 

make a habit or assigning a lower precedence to inf'ormat1on addressees when 

pract1.cable, communications will be able to function more rapidly when speed is required. 

The 'following considerations are also or great importance 1.n the intelligent us~ of precedence: 

1. Precedence begins when a message ia drafted. It is only fair to 

expect originators and releasing officers to handle it with the same 

speed they expect Of CODlllUDie&tions. 

2. Precedence is a guide tor communication personnel, not addressees. 

It ia better to aak whether the text alone requires prompt action than 

to 1naiat on speed or transmission. since high precedence gains speed on 

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REF ID:A719. 

1H!IB'fRI9HB - JANI' 143 

the circuits only and does n"t require prompt action on the pa.pt or the 

addressee. 

3. 'l!ime zone dif:f'erences bave an im ortant beari on recedence. For 

exam.le, routine precedence may be too high tor a westbound message and 

too low :f'or an eastbound message. It is not intelligent geners.lsh1p nor 

admirable naval tactics to assign a precedence which results lu delivery during the night when no action is necessary until the follovi1ig morning· 

DOES IT SAY WHA'l' YOU MEA'N? 

Drafting the text with completeness, clearness, and brevity is never easy. Patiencef practice, and resourcefulness are needed. The first try is not likely 

to be satisfactory unless the drafter has had thorough training and considerable experience. A dictated m~ssage is almost certain to be wordy and therefore very unmilitary. rr it doesn't contain too many words, it probably contains long, pompous ones which are out of place in message texts. 

Completeness is the first requirement of a well drafted message. Ir it 

does not give all the necessary facts, it may be little better than no message 

at all, especially vhen combat is imminent or in progress. , Durin~·1943 the enemy was able to sink one or our ships and escape unharmed from American waters because or incomplete messages and failure to send 

a message at all. One plane reported the rescue or survivors but :f'alled to 

give the time or position or the attack, or the course or the enemy ~ubmarine. 

Another neglected to make an amplifying report. A third plane failed to give the position o:f' the submarine or to communicate with a plane which wa.s in a 

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

code when speed was vital and plain language would have t>een of litt Le value ~ 

the enemy. Accuracy is also of vital importance. Downed aviators V•)re sometimes lost during the war because repot>ting planes in their eagernes:1 to hasten 

a rescue gave incorrect positions. Le.ter corrections did not always get through. Numerous instances could be cited. 

Clearness is another major :f'actor in message drafting. A message which 

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

read with two quite di:f'ferent meanings is likely to lead to contusion and 

disastet'. This fact was forcefully stated in a CIBCPAC-CIBCPOA repo1•t of 

operations in the Paci:f'ic: 

"A little thought will show that the dispatches one sends Dlfl,y be 

more vitally important than anything else he is likely to de• in 

the battle; and that however great the stress of the situation, 

one must apply to their contents and phrasing the same cool, calculating judgment that he would use in spotting 'salvos, laur1ching bombs or torpedoes, or maneuvering his ship or plane against the 

enemy. 

"Let us suppose (for the emphasis or comparison only) that one of 

our ships or planes should desert in the face of the ene1117 and seek 

safety in flight, or that its personnel should be so fluatered by dangel' as to be ineffectual in the battle. 'l'he very thought is 

·abhorrent to us; and yet if this thing should happen, the harm done 

mi8ht not be serious. It would be only one unit failing; and others ~f sterner stuff could be counted Qn to make up tor it. 

"But a single inaccurate or misleading dispatch, though dratted 

by someone of impeccable loyalty and courage, can easily work rar 

greater harm than the toregoing suppositious defection, sinc9 it 

niay be the cause or error or delay in the action taken, not aerely 

Original 

13 
REF ID:A71913 

by one plane or ship, but by whole groups or forces. Thus, f'rom 

the standpoint of the results, a force thirsting for combat with 

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

too-hastily worded dispatch ma.y f'ail as badly as though it had 

little stomach for fighting at all •••••••••• ~ 

Lack of clearness affects communication security as well as operationil security in a very definite way. If time permits, each addressee must ask 

fo:r-. clarification. The resulting exchange of communications may not be cornpleted during .the day on which it began, and in wartime call sign ciphers •>r 

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

CAN IT BE MADE SHORTER? 

Studies indicate that messages can be clear and complete yet consider~.bly 

shorter than the average military message now is. Here are f'ive ways in which 

brevity can be ~chieved: 

1. Kill unnecessary am.pli:t'ying detai!s. Strike, search and intelligence ~eports were frequent offenders during the var. Only in.formation 

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

2. Strike out superfluous words such as number, following, and ~ted, 

before submitting a message for release, thus: 

As Sent 

reurser numb'er 981 

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

following items needed colon 

accomplish repairs 

to ef'f'ect repair of 

Recommended 

REURSER 981 

ANSWERS YOUR 

URLTR SIX JULY 

CNO 292359 JUN 

NEED 

REPAIR 

TO REPAIR 

Saving 

43~ 

6~ 29.' 

4~ 

84~ 

65%. 

50$f; 

and 

A 

east 

submarine 

18 times 

in 

in 

the 

a 

eastern 

single message. 

Mediterranean 

Neither 

in 

word 

one instance 

was needed 

used 

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 followtng subs~itutions 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. 

Saving 

~~ 44~ 

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

often. Advise earliest practicable shippinfwdate might well be replaced vith the simple question HOW SOON CAN YOU ~D. 

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

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

phonetic words--unless the word itself is shorter than the phonetics fo~ 

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

Original 

14 
• 

REF ID:A7191.9 

JANP 143 

but ABIE SLA.'RT CHARLIE is twice as long as AIRCRAFT • 

• 

5. Avoid unnecessary use of' "Phonetics. They only waste SJ:&ce in 

expressions like UNCLE SUGAR MikiSOCHARLIE, but they serve a usef'ul purpoae in LOVE SUGAR TARE when used apart f'rom the name, number, or other iden-

•tif'ication. The f'ollowing is an extreme example of' phonetics gone beserk, 

all of' the expressions having appeared in a single message of' D'1edium 

lenJtbl 

CHARLIE OBOE MIKE DOG TARE NAN YOKE DOG tor COMDT 'NYD 

·SUGAR OBOE NAN YOKE DOG tor SUPOF NYD 

UNCLE ROGER SUGAR SI.A.NT ROGER apparently for ORSER 

ROGER YOKE EASY XRAY PETER BAKER SLANT LOVE apparently for 

RAIIMAY EXPRESS BLADING 

ITEM NAN VI~TOR apparently intended to mean INVENTORY 

This little orgy lengthened the message by 18 groups or about 2o,;, 

and the meBBage would have been 10 groups shorter than it was ~.f' all 

of' these words had been fully spelled. 

Other useful ways of achieving brevity include the deletion of unnecessary punctuation. Telegraphic style has small place for it, and its use should be se~erely limited. Combining reports is another important way to reduce traff'ic. 

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

if required less frequently. 

DON•T QUOTE • 

Quotations from another message or almost any other source are a security 1-1.&zard. The danger is much greater with some cryptosystems than others, but 

an originator has no way of knowing which cryptosystem will be used. The rule 

is theref'ore very simple: restate in different words if' necessary, but avoid 

verbatim quotations. 

WHAT ABOUT THAT REFERENCE"i 

References are security hazards if they appear too often at tho beginning of a message. They should be buried in the text. Plain language roferences 

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

referenced messages. For this reason plain language :r>eferences to oncrypted 

messages a.re limited to those which consist of the date-time group J•eference 

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

POES IT AFFECT THE NATIONAL SECURITY? 

The f'ina.l responsibility of the drafter, once he has assigned a reasonable 

precedence and drafted the text securely is to classify realistically. Overclassification on a large scale undermines respect for the higher classifications, overloads the secret keys to cryptosystems, and encourages laxity in 

handling and safeguarding documents and the info:r:mation they contain. Underclassification is dangerous but much less common. Frequent reference to the 

definitions of Top Secret. Secret, Confidential, and Restricted in Army or 

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

between underclassification and overclassification. 

Qriginal 

15 
• REF ID:A71913 

llBMB!elED 3A1fP l.lf.3 

• 

• 

I 

16 
REF ID:A7191ft 

CHAPTER III 

COMMUNICATION SECURITY IN PEACETIME 

JILNP 143 

The continuing importance of' communication security cannot be c>veremphasized. Since the cessation or hostilities a large volume or classified 

information has been downgraded; however, a tremendous amount or intormation 

remains classified and of' vital interest to the national security, nnd is 

constantly being added to by current developments. In addition, potential enemies will have more lei~ure in which to attempt penetratian or our security •barriers. 

It is essential that the elements or communication security be understood 

and provided for at all levels. Those who use the communication se~vice must 

learn and practise the drafting of' clear, complete, concise message3, and 

assign realistic classifications and precedences. Physical securitj must be 

considered. Efforts to steal, copy, photograph, or otherwise obtain cipher keys and specifications of' our cryptographic equipment are not likely to 

diminish during peacetime. Many of our ciphers will be le11s expose•l to capture, but infiltration of' enemy agents may actually be facilitated by the unsuspecting nature of Americans. Security of thought, word, and action are requisites. Pub1ic places and desk telephones do not provide th~ secure conditions necessary for the discussion of' top secret matters by high-ranking of'fice~s or others. 

Security is one of' a commander's best defensive weapons. It i~ also one 

of his prime responsibilities. The successful officer will know th·~ rules and 

procedures designed to provide security, an~ he will follow them. 

Original 

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