REF ID:A488484 

WDGSS-14 7 December 1945 

SUBJECT: Minimizing Adverse Effects of the Joint Congressional 

Pearl Harbor Investigation 

TO: Chief, Army Security Agency 

In accordance with your request of 4 December 1945, there is 

submitted herewith a draft of a paper on the subject noted above, 

with the recommendation that it be forwarded to G-2 for consideration. 

1 Incl 

Rpt - "Pearl Harbor 

Investigation, Minimizing 

Adverse Effects of" 

WILLIAM F. FRIEDMAN 

Director of Communications Research 

Declassified and approved for release by NSA on 11-06-2013 pursuant to E .0. 1352a 
1: 

REF ID:A488484 

UJt ~aJJ~E1 1/IDGSS-14 10 December 1945 

SUBJECT: Pearl Harbor Investigation, Minimizing Adverse Effects of 

TO: Deputy Chief, Military Intelligence Service 

Room 2E 800, l'he Pentagon 

Washington 25, D. c. 

1. The testimony now being presented before, and the results 

being produced by, the Joint Congressional Investigation of the Japanese surprise attack on Pearl Harbor on 7 December 1941, are being 

widely publicized throughout the nation and the world. This testimony and the results of the investigation will probably have a very 

important direct effect upon our future activities. They may also 

effect the War Department as a whole, the Navy Department, the State 

Department, and other governmental departments. They may, in fact, 

impringe on future Army-Navy relations, as well as United StatesBritish relations in the communications intelligence field. 

2. If certain phases of, or lines of questioning followed in 

the investigation are based upon serious misconceptions, misapprehensions, and misunderstandings relating to cryptologic science, as 

seems obviously to be the case, then it appears to be important to 

try to remove the basis for them insofar as possible, by adopting a 

course of action likely to bring a better understanding of the basic 

philosophy and techniques upon which cryptologic science rests. 

J. Some of the misconceptions referred to in paragraph 2 are 

as follows: 

a. That hundreds of messages offered in evidence constitute 

documents the availability of which is to be taken as a matter of 

normal expectancy; that it should and can be taken for granted that 

the solution of cryptograms is something that can be achieved under 

all circumstances; that the Army and Navy communications intelligence 

services should and can always be expected to be successful in doing 

so because it is normal to expect them to do so. 

b. That the reason for trying to suppress all the facts 

concerning the Pearl Harbor disaster was purely political; that there 

was no sound reason, other than political, wh~ all the facts concerning the disaster should not have been disclosed immediately or soon 
WDGSS-14 (10 December 1945) 

after the event; moreover, that even at this late date there is no 

reason other than political for withholding certain facts, because 

there is no further need for secrecy about any aspects of the disaster; 

finally, that no harm whatever can come from a full and complete disclosure of ~ the facts. 

c. That cryptanalytic processing can be conducted on a production line assembly basis - the raw material can be inserted at one 

end of the line, and finished intelligence emerges at the other. 

d. That the solution of the Japanese codes must have been a 

relatively simple job, judging from certain of the messages entered 

in evidence, such as the Trans-Pacific Telephone messages, the Winds 

Code messages, etc. 

e. That the Army and the Navy were delinquent in translating 

certain messages, and that there were numerous avoidable delays; this 

leads to the misconception that the business of solving and translating 

cryptograms is now as simple as, or only a little more complicated 

than, reading the daily newspaper. 

f. T'nat information that might have been sent to the Commanders in the field but was withheld was so treated because of serious 

apprehensions regarding the security of Army and/or Navy cryptographic 

systems. 

g. That the Army cryptographic systems are far interior in 

security to the Navy systems. 

h. That no code or cipher can hereafter be trusted; that they 

can all be read and read quickly by experts; that therefore, ap1Jrehensions as to the security of our highest governmental communications 

are warranted. 

i. That the information derived from communications intelligence was improperly handled before Pearl Harbor, and therefore, it 

was probably improperly handled after that disaster, so that the contribution of communications intelligence toward the ultimate victory 

must have been quite insignificant. 

j. That a world-wide spy system would produce a greater 

quantity of reliable intelligence than communications intelligence 

can produce. 

k. That the solution of some cryptograms involves slight-ofhand, legerdemain, mystical processes and guess-work; that one can 

never be sure of the validity of the trl\11slation of a cryptogram; 

f Of ~ffiifi1t · 
1: .. DC',S3-J..4 

that the science of cryptanalysis does not rest upon the same secure 

foundation that other sciences rest upon, and that therefore, the 

validity of the results of cryptanalysis cannot be demonstrated and 

proved, as can the results of other scientific work. 

1. That building up a staff of cryptanalytic experts is a 

simple matter, to be taken as a matter of course because there are 

in civil life experts available in all fields of knowledge, including 

cryptography and cryptanalysis. 

m. That governmental cryptanalytic activities during peacetime can be conducted in the same manner and on the same basis that 

all other governmental scientific activities are conducted, whereas, 

as a matter of fact, from 1930 to 7 December 1941, the government 

itself, by engaging in intercept and cryptanalytic work, conspired 

to violate the law by inducing and hiring people to enter upon 

activities which are under our present laws criminal offenses, and 

which made every member of the communications intelligence services 

of the Army and the Navy subject to heavy fines and imprisonment. 

If anybody wanted to make a test case, it would have been possible 

to prosecute and possibly convict all members of those services during 

the period indicated because they themselves did or caused others to 

perform the following acts: interception, solution, translation, and 

dissemination of the very messages introduced in evidence in this 

hearing. 

n. That the obtaining of the raw material for cryptanalysis 

is an easy matter; that the interception of all radio traffic is an 

easy matter; and that the obtaining of cable and wire traffic is to 

be taken for granted at all times, whereas, as a matter of fact, it 

is decidedly illegal under our present laws to do any one of those 

things in peacetime. 

4. It is unnecessary here to set forth in detail the facts which 

may be adduced to combat the misconceptions listed in paragraph 3. 

These facts are well known to those who have had the advantage of daily 

contact with the work of and the results obtained by the communications 

intelligence services. But these facts are not so well known or clear 

to the members of the Joint Committee or to its Counsel. To give them 

an opportunity to learn these facts would be conducive to the public 

interest. It would obviously not be necessary to spread the facts on 

the front pages of the newspapers of the country; but by giving the 

Committee and its Counsel a better conception, appreciation, and understanding of cryptography and cryptanalysis, it is possible that the 

serious danger to the future continuity and success of our communications intelligence services that will result from a full disclosure 

of all the facts may be .minimized. 
REF ID:A488484 

WDGSS-14 (10 December 1945) 

5. There is an additional reason for 1•educating11 the Committee 

and its Counsel. No matter what happens from now on in the Pearl 

Harbor investigation, sufficient information concerning cryptanalysis 

has already been disclosed to put every goverrunent in the world on 

guard against the communications intelligence services of all other 

governments. They are going to look into and improve their cryptographic techniques and methods, with the result that we may now look 

forward more or less apprehensively to the time, within a few years, 

when our success in the cryptanalytic field will be a glory of the 

past. This will be the case unless we are provided with the means 

for expanding our research to the extent made necessary by the ve?""/ 

disclosures of the present investigation. We will need to do more 

work than ever before. There are on the Corwnittee members of Congress 

who will be in a position to help us obtain the necessary legislation 

and funds to support our work. By neducatingtt them we will help ourselves. 

6. It is therefore recommended that steps be taken as soon as 

possible to invite the whole Conunittee and its Counsel, together with 

the new Chief of Staff and the Secretary of 1lar, to visit this station 

and to make a tour of its activities for their better orientation in 

cryptology. And the psychological ti.me to do this is !!£!!, not six 

months from how. For we could not only capitalize on the undoubtedly 

good impression which General Marshall will make on the Committee, but 

also take advantage of the circumstance that the Counsel of the Committee now appears to be surfeited with the uninformed line of questioning followed by certain members of the Committee. 

4 

W. PRF.STON CORDERMAN 

Brigadier General, USA 

Chief, Army Security Agency 
t 

REF ID:A488484 

"H1GS:·i·l4 7 DeceMber 1945 

f.UBJF.CT1 Minimizing Adverse -.rfeets of the Joint Crmgressional !'earl 

lforbor Investigation 

'l'O: Chief, Army Security Agency 

In accordance with your requee::t of 4 Decellber 1Q451 there is submitted herewith a draft ot a paper on the subject noted above, with 

the recommondF'.tion that it 1)9 forwarded to G-2 for conai1 !eration. 

1 Incl 

Bpt - "Pei:irl Herbor 

Invest1gntion1 Minird.sing 

Adverse :tf ects of" 

WILLIAM F. :FRIEDMAN 

Director of Com1!1Un:lec.t1ona Ji.esearch 

'. 
I 

REF ID:A488484 

T01 :iep11t.y C'~·ief, 'U.litnry Intelli~ ::Jarviee 

'fi 0'1'tl 2E ~ 1 The ?ontngon 

.. ,,, ~r1. tt;;+..(.'.1!1 "'":i, D. C • 

1. The tP~t.lmony !!OW being pre1entcd be~ol""J, and the rr,su.li:.s 

l-'f'ing !'t!"CWlttcf'.\d by, the Joint Cf'.ln,'r1"9cdcml !mrestigfition c-r tJie Japanese mu-prise at-+Dek on Pearl Re"t"bor on 7 !"ocember 1941, aro being 

rirlely publicised throuFOU't the nation !'.l.M thf!t worlcl. !h13 tost1-

mC'>n7 P..M +.he !'{lR'll ~.s of the 1nvest1r,et1rn rill probably hmre P.o very 

lmpC"r+.r.:nt 1ire('t eff".'ct. 1'!'}()n oor futu.ro activities. T~ey !':J.fj7 also 

offeet -the '.'ar !'epartment as a whole, the lavy Depart•1ent, the State 

Jflpe.rt:nent, t'l.nd other goyernmental 1epe.rtwmta. They rllJ.Yi 1n feet, .t··Tin;~o O!'I f"ut11re rm::-1fo·,ry reletiona1 as well r.s ~Jniterl 3tatos• 

"'rltish r·~lati~na in the c~1~'tions inte1lic;Pnce field. 

2. If certa.!'l "h"' ~es of, or lines of quarJticni!lg f'ollcmed 1n 

the i 1'1'3~tir;-<ltion t1~ ha"ed 'lpon serimu: ·1bconceptinns, :--iasp;,.:rahen-

'Ji .-,ns, r,!rl mis•mr3 erstlllnUngr r~le.ti""' to cryptologic scienc'!! 1 as 

B'il.,Yllll ribrlouely to be the el'! se, then 1 t s:p~.lesr.s to be i'llpOrt.ant to 

try to t'e'!llO'Ve i.hft bl!si~ for thert insofar :its poaaihle, by adopting a 

cou:rne of "et.ion likely to hring "' hettt.r u'l'rlerstanding or the haaic 

r>hll09ophy Mid technirimns upcm whieh cryptologic se1~nae ~ate. 

J. So'Tle 0f the ~·tseoncepticnB reff!rred. to .ln ]1f.ragrapb. 2 are 

~s follcw11s 

a. That hu'1dreda ot mesea:res offered ln evidence constitute 

documents tbA SV'Bilabilit7 Of Which :l:i! to hq tn.ken l!l! fl, ri.atter of 

nomf\l t!~ctanc:n that H sh®ld AD:l Mn ~'le U:iken for .'!1'9.nted tlw.t 

the 1Kilut:ll".ln of crYTito".r&.ms 1e somethin~ thet cen bl! echieved unier 

ell ci.rCU11etances1 th~ the Arm7em N11JV)" commun1cat1on1 1ntelligenoe 

services should en:l cen. alw:re be expected t,o be s11cc-esafltl in doing 

so h•!'.h'ttuse 1 t ie ·:.,rmnl tC> .,xpect t.he11 to do so. 

b. That the reason for trying to auppreaa a11 the f'ucts 

eoncel"l".ling th., P~· rl Harbor disaster 'lt'ae pu.?"ely po11t!oal.J that there 

•• no aound reason, other than political, wbT ~the taota concerning the disaster should not have been disclcsed innediately or noon 
c 

REF ID:A488484 

i'iDGSS-14 (10 December 1945) 

after the event; moreover, that even et this Jate date there is no 

reason other then political for withholding certain fects, because 

there is no further need for Becrec1 about any aspects or the disaster; 

finally, that no harm •hatevar CA.ft come frott A tu.tl and complete disclosure of 1JJ. the facts. 

e. That cr.yptanalytic processing can be conducted on e production 11ne assembly basi1 - the raw materiRl can be inserted at one 

end or the line, 'lnd -finished intellicrence 8!'1erges et +..he other. 

d. That the solution or the Japanese codes must have bean e 

relativel1 siJlple job, judging from certain ot the messages entered 

in evi<~ence, itUch as th~ 1rans-PRcific Telephone meaS8rr&•, the ~lnda 

Ccne rtiessar:ee 1 etc. 

e. 'That the Prny and the ~avy were delinqufllrrt in tnnsln.ting 

certain meaeaf"'8s 1 nnd that there were nu..'llerous avoidable delaysJ this 

leads to the misconception that the business of solving and translating 

eryptor,rams is now as simple as, or only a little more eonaplicated 

than, reafiing the daily newspaper. 

r. The.t infonnation that ":light. hAve been sent tt"> the Commanders in the .field but was withheld was so treated because nf &P-rious 

apprehensions l"eo/\l'(Unr; the security 0f Amy nnd/or Navy cryptogl"aphic 

nystAma. 

g. Th.at the ~rmy cryptog~phfo sys1.~mt1 e.!'o fnr tnf~rior in 

aPcurity to the Henry systems. 

h. i~hst nr> ecde or ei~'1her can h'?~fter be trustedJ that they 

csn ell be rend and read quickly by expert.SJ that therefore, apprehensions RS to the security or our hir;hest ~overnrmental CO'Jl1llW'Jicftt1ons 

arA we. rre.nted • 

1. 'lhet the infnl"Ulfltion deriven .f'rm eormminlcatitYr•s intelli-

-~ence was improperly handled bef"lre μe5rl Horbol", snd t!le~fore, it 

was probllbly improperly handled After that disaster, 110 that the contribution of CorrummiCEltio!'IS intelli~EmCe ton.rd the ultimate victory 

m11st have been quite ins!gnH'icant. 

j. •:'he t a. world-wirle spy system would rroduce a f;?'e'-'-t.e:r 

quantity of reliable intelligence than communication• intelligence 

can produce. 

k. Thnt the eolution of sO'!e c:ryptof!ram:s involveA elight-orhand 1 lezerdemain, mystical processes e.nd guess-workJ t.Mt one can 

never ~ sure of the validity of the translation of a cryptoeramJ 

2 
I 

I 

REF ID:A488484 

th,,t th~ acienoe of cryptanalysis does not rest upon the same 8t~ure 

foundation th11.t other ecienoea rest upon, "m thfl.t. therefore, the 

validity or t.he resulte of cryptenalyais oannl\t he (~emonetrated and 

prove0., as ce.n the rerrultfl nf other ecientitic wc:>rk. 

l. That building up a staff of cryptanalytic experts is a 

simple Mtter1 tc be Uken as a r:iatter o.f course becAlu1e there are 

in civil life ex~rb! P.vaileble in all fiell~fl of knowledge, including 

oryptor1raphy end crypt.analysis. 

m. That goverrmient.al crypte.nnlytic activities during peaeetiiw can be comucted in the ome manner Pnd on the same basis that 

s.11 other governmental seientitic activities are conducted, whereas, 

es a MRtte:r of ft>et, fro'll 1930 to 7 December 1941, the government 

itRolf, by ene;e.ging in intercept nnd cryptanRlytic work, conspired 

to violnt.e tho law by inducing Pnd hiring people to ent.er upon 

tJ.ctivltiee which are wvler our presr.nt laws criminal cffenecs, n~ 

which iiade r:?very menber of t.he communientions intelligence services 

of the ;~rrn.y f!nd the !1t-vy subject to hervy fines El?ld imprisonment. 

If anybody wuntOO. to '".eke a test ce.ee, it would have been po1rnible 

to pl'o!lccut.e nnd possibly convict all !'\ellbers or those services during 

the period indicf'ted hecau8e they the11"eelvee did or caused otherfl to 

pe:rfom t.he following acts z interception, solution, tni.n31ftt1on, end 

dissemination of the very meaeap,ea introduc~ in evidence in this 

hear1ne. 

n. 'ih~it the obtaining of the raw '!llt'tl"rilll for crypt.aruil711i1 

i ~ <?n or, ry ·-:~ t te?·; th~t the int-erception of all radio traffic ia an 

e'flsy natter; and that t.he t1bte!ning of cable and wi~ tra.f!'ic is to 

be tl'ken for .. :ranted l",t. all ti!:'les, wheree.s, es e r1fltter cf fact, it 

is ~eddedly illeeel under our preeent Jaws tci do any one of U-_oee 

tbin~s in !J0&Cet1.'ll8. 

1,. rt is unnec-.nsa17 hAre to set forth in detail the facts which 

mny i.''49 eictducoo to com.'l::lp_t the mbeonce"'tinns lietea in pen.graph :;. 

'!'h£>Se r!'.CJ.;.~ are \·.•e 1 1 1""r'O'ITT1 't·O t boee Wf'O b.We had tf1e advsnt&.~e of daily 

cont' C't with the c•,ork l)f find the rasulte: ('lbtained by the co-u1;mmi.cationa 

inte111~~~nce 1ervlcee. F:ut t heec f .. •cte el"'fJ not eo well known or clear 

to tht'I me'Tlhere of ihe Joint C()111"11ttee or to its Counsel. To give them 

an opporbYii ty to leEtrn t.heae fscte •nuld be conducive to the rublic 

intf'rc."lt. It !"Nt1d obri"usly n"t he necessary to spreed the fects on 

the front peges of the newspapers of the eountrn but by giving the 

Committe., nnd its Counsel n better conception, appreciation, end understanding of cryptography snd cryptenalyeis, it is possihle that the 

serfo1w ,•enger tC1 the fut~ continuity ATI!1 success ~r our com:>iunicaticne intelligence services th~t -:.vll 1 l"lsu.lt fran "' f'nll d!scloaure 

of all the racts mey be mbi'nlzed. 

3 
I 

REF ID:A488484 

YmGSS-l.J. (10 T"'.ecember 1945) 

5. There ie sn additional rl38eon for "educatingu the CO!'n'!!ttee 

and its Counael. No Mtter wheit happena f'rcllll now on il'l the Pearl 

Harbor inveetigf!tion, 11\lff'icient information concerning cryptanalysi1 

he!'! already been rt!aclosed to put "err gO'ftrnaent in the world i')ft 

;;uard against t.he cmmunicr.finns inte.1.J.i~nce services "' e.ll ot.her 

goverments. They 11.re c:oine 'to look into am improve thei.r cr:Ttographic tfllchniques and !lethoda, with the resul.t thttt we TM.1 now look 

fonard ·nor.- or lee!: apnrehendvely to the +,i111e, within a few ye11tr1, 

vrh~n 011r 911cc.es1 in t.he crYrtanalytle fielrl will be e glory "'r the 

pant.. 'f)1is will ~ .e the ea so unless we e:re ::-irl"lvMM witt; the moana 

for e}-;mnding cmr ~aer>.reh t.he t t ntad t 

tr :<1e t i:rat -;;.., wi.11 "ieed t.o rfo J!llOft 

wor than ever before. 'There are on t COl!lllitt.e JMlflbers ot Congre11 

who w111 be in a poait!~n to help us obtain the necessary legt.!l!tiop ~nd funds to 911pport our worlc. Ey "educating" thP.m w1t will he :r oarsrilvee. 

6. It is t>e~i'ore reeG1!11'18med tha+, steps he t."lk"n n.s sol'>n As 

poe~:t·111! to invl t'! +)1~ ·1hole Co"~":l.itteo t1m itA Cn11't'!iMl, to51lther with 

the ne·.v C'',ief 1,f ::taf_r l\nd the Secret~ry or ~ia.r, to v1eit this station 

an~l to T'18ke A tour of its activities f'or their better orif'nt8tion 1n 

err_ritoloey. tnrl tho psyeholo:;kRl t.1.me to do tfli8 is J1SZl1 not SiX 

~on+..Ji s r,..,,"' nrnf. i-'l'>r ~" etittld not only c~pitAliPct on Ui~ u-:irltl1.i.htedl7 

'".OOn im,..,!'f'l~sion 'Whlch c;..,nernl M:~r8hall will llr.ke on the C0!"1~ittet"t 1 but 

Also tnke advantar,e of thtt c1rcumst.f4n°"' thnt t.h~ C"1tn8'll t?t t.he Committee now apne9.r1 to be ~f'ei ted .;1th ·t.he llnin:f'ona8d line nf {'_nestion3. n; foJ. 1 nwed b;ir certnin memhf'.JrR or the Co:ini tteo. 

71:. IFEm'ON r•JJ'W.'Jt!\(t\lf 

nr i;_:-snier G OM rril, lJ.SA 

Cld~f 1 Arny ~cul"i ty Ar,eney 

4 

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