.. 

17 April 1951 

Ml!MORANWM FOR J\Ji'&.-OOB 

SUBJECT: C:eypto-Securi ty" of AFSA Communications 

1. I am deeply concerned over the security of our COMINT comm.u...'1.icationa from a cryptanalytic viewpoint. A cursory examination of this problem indicates that crypto-systeme current.\y in use between .AFSA. and :f'ield. 

organizations (i.e., theater processing centers and intercept stations) 

and from units in the field to main processing centers for the passing 

of ra.w intercept and COMINI' 1Ii8¥ be subject to successful atts-0k by eneJiij' 

or foreign OOMil't'T organizations. Aa an example MIN.l!RVA (AS/~'1 2-1) 1a 

used to forward raw intercept and daily coverage reports :from :field uni ta 

to AFSA and from field units to theater headquarters. It is an accepted 

fa.ct that this system can be aucceasi'ully exploited cry:pta.via..1.ytical~ 

under certain condi tiona which ~ frequently occur. Likew:hm, equally 

vulnerable oopects of our communications may be exploitable th!'ough traffic analysis end vital intelligence gleaned therefrom. 

2. '.I.he :present coIJl:Plexi -cy- of the CO.MIN!' problem. as a whole, emphasizes 

the need for maintaining a close securi cy check on our own coill!lU!licn~~ions 

in order to minimize, 1f not entirely eliminate, the posaibil:tty o'! fl.DY 

knowledge of U. s. COMINT activities being made available to enemy or foreign COMIN.r organizations. The outbreak of hostilities in Kores, end 

particularly the entry of Communist China into the conflict made it necessary to read.Just our COMilfl' effort. .An expanded and accelerated ,-Jrogra.m 

was instituted, as a direct result of which not only wa2 the vo.lu:ne of' 

raw intercept subatantiaJ.ly increased., but providing for the rapid forwarding of additional volumes of tra:ffic became an operational necessity. 

A concomitant growth was evident at unce in the communications voJ.nme 

from AFSA to the field in order to direct this expanded intercept ef'f'ort. 

As an example in June 1950 AFSA received by electrical :means an average 

of 494,826 groups daily of raw intercept. By March 1951 ·this avere.t;:i 

hm increased to 823,443 groups dai.13. A correspondiri..g L11.Creaae :l.n volume 

has also ta.ken place during the same period in outgoing groupsge from AFSA. 

I think it also :pertinent to :point out that this already complex problem 

is steadily increaaing in complexity and size. Long-rar.ge :mbillzation 

planning for AF&'\ has as its nucl.eu.s a. greatly expanied intercept ef:fort 

which will of course :L."lcreaee the amount o~ raw traffic available to /\:FSA 

and in turn increaae the voluloo of conmunica.tions among Ji.FSA and field 

units and other proceaaing centers. With this growth the need :for ms,intaining a close watch on the crypto-secur1ty of our commw.U.cations becomee 

even n:ore necosmu-y. 

3. To the beet of lD3" knowledge it hes been a long time, perha.:ps 

too long a time, since this matter has been looked into and diecusaions 

held among repreaentatives of appropriate divisions of AFSA. It seems to 

me to be entirel..v worthwhile to review the entire problem; to ascertain 

the weaknesses, :tf any, in our present crypto-s;rstema and their use and 

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Declassified and approved for release by NSA on 05-16-2014 pursuantto E .0. 1352a 
'1- • •. .. .. 

SUBJ"Ea.r: C';nito-Securi -cy of' AFBA. Canmnications 

to :formulate new procedures am teclmiques :for coping with this task 

wherever and whenever the need appears. I bel.ieve that our vulnerability 

both .from. a troffic analytic end cryptana:cytic viewpoint should be thoroughly explored. Indeed, the time is now ripe, for AFSA ha.a been organized 

and opera.ting for o\rer a. year. 

4. According.4r, I propose that a :P8JJ0l be ee·te:t>liehed composed of 

representatives of /·FSA..-02, AFSA-041 and tm1' other oosnizant gt"oupa, to 

mBl!:e a stl.1.d.y of this entire problem. and upon its com;plet.ion to su.bmit 

their f'indinga and recolllllenda.tions to BmAFSA. I further propo13e that 

this panel be permanent and that it meet at stated intervals to re..,riew 

the vulnerabili tcY' of .AFSA commun.1.ca.tions to foreign ·~Ol-1..INT effort al1d 

report its f'iud:lnga mld recommendations. · 

5. Your gu.id.aDCe in this matter is regμ.estecl. ~ ~/) -~ l~lj)r_, 

SA-oar 

AFSA-OOX 

AFSA-04 

AFSA-l.3 

2 

/l"t..-fl./ f 

F.RANK :B. ROWIE1.T 

Technical. D:lr6ctor 

Office of Operations 

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