'1'RESB BECOBDS WILL BS / 

l"OR OPl'lCIAL PDBPOSES~ 

, DO_.~OVi. 1'~ .. ~ - -'l'(f 'Dflllf'[S) ' 

'=r: ... DAT& OP BlilQ'Dml' 

II PU .• £ 1 OR _s. ... 

From.the Files of the Special Consultant Friepdman) 

-...::::::: 

, ' ,SE.RIAL ( ) 

,- 'NuliiaER~ Final Vers;ion of Lecture' No. l_- 2.1. pages carbon copy , No. 2 - 24 pages,, , ··.AND • .No. 3 19 •pages and 1 page ·.of notes. CONIID!HT11tL 

/'' ~f!U,~JKC:! ' '• , ' - I .--:::--:·~·~ .. ~~=-:t-'1f~=-Ai~~llli~~~~iRii5NRimniiiTiiiei'Pn:R-::-.-Oii:i1iA'iiiiilTiiiiif.BiiiiLi>Dii~un:iR.l5mi"'iiiiiiiiiiiir--------:--- 1 ' ' , .. , .., ... ,... ON BJllQ'Oli1BTING PILB I OROAmZA'l'lON, B'DILDINO, ARD, BOOK NUMIBB , ; 

·' • To Mt. William F. ~Friedman ( Hom~ ) Special Consultant ·' ~ 

RETURN 

TO, • 

DAT& RB'rND lNlTlAL HlllRll 

SA'.. Records Management' Br, AG-24 - -~-<·!'._,,,_t.lt'_is_t_i_an __ __,...._ ___ _,_ ______ • 1 

' ' WBEN 'l'lUNSP'ERRINO P'JLE TO > ANO'I'Rl!:R PBRSON CO'MP'l.E'FE BELP-ADI>lU!ll!SBD 'l'RIANSP'l!lR COUPON, BELOW, l)JBTACH;. 

1 

1

1NSTRUCTIONS STITCH TO BJ..A,."(K LETl'ER-SlZ&,, PA.PER AND PLACB' IN OD"r-aonro MAIL SBRVJCJ: ' 

., ·-.., .. ~-·· ... . , {-- -~~--- --iNoTRANSFERcmiPON-->----· ~- 1 

" 

I 

TO: " 1' • 

... . ('f') 

' C\J ... 'l'RA=""""H"""Sl'BRBl!ID==~TO,,..,...._(D_a_m_e -.-Dd.,--eateDlllOD) 

~ 

C\J 

, LO 

J_Q.d-~ .. 

-ORGANIZATION, BUU.OINQ, AND ROOM NVQEH 

DATB ,~. 

~ j__ 

Declassified and approved for release by NSA on 12-16-2013 pursuant to E. 0. 1352B 

• t l ~ ' . 

text1 

--

• 
REF ID:A6286. 

CONFIDE-NTmAL 

LICTURI I 

'l'he objective of tbia 1erie1 of lectures 11 to create an awareue11 of 

the backgrOUDd, developnent, &D4 mnner ot empl.OJmDt ot a science that is 

the bu!• of a vital military ottenaive and dete.aaive weam known .. 

CR!Pl'OLOGY 1 a ward that comes trom the Greek kryptos 1 meaDing secret ar 

hidden, plus logos, meui.Dg knawledge or learAiy. Cryptol.ogy will be 

specifically 4efi.ned a little later; at the moment however, I'm 1ure JOU 

know that 1 t hu to do with 1ecret cammmicatiou. 

Let me say at the out1et of these lecture1 that I ~ tran time to ti. 

touch upcm •tter1 which are perbap1 ea1ent1al.ly peripheral or even irrelevant 

to the main iaeue1 ot cryptolo17, a.ml if a 4efe:ue is neeclecl tor 1uch occuicmal 

brawsing along the by-11878 of the aubJect while travelling along the •in 

highways of the science, I'll 1ay that long preoccuiw.tion with any field ot 

knowledge begets a curiosity the 1ati1taction ot which i1 what 411t1Dgui1hea 

the ded1cate4 protea11onal from the per1on who merely worb Juat to gain a 

livelihood in whatever fiel4 he happeu to t1Dll bimllelt a Job. That's not 

much tuu, I'm afraid. By the way, a British writer, Jue1 Agate, defines a 

profeseiona.l. as the man who can do hi• Job even when he 4oe•n't feel like 

doing it; an. amateur, u a ma who can't do his Job even whell he does feel 

like doing 1 t. This 11 pretty tough cm the gifted amateur d I tar one 

von•t So all the way with Agate•• 4et1ait1on. There are plenty of 1.Datance• 

where gif'ted amteurs have dam and 41acovere4 thinp to the chagrin and reelface4ne11 or tbe prof'eaaicmala. 

GaNFIDE:.NTIA~--
-

REF ID:A62869 

Coming back DOV to tbe •1D thoroughfare after tbe foregoing brief 

Jaunt along a bJ·W&71 I my well begin bJ telling 7ou that the science ot 

ceyptology baa not alvaya been regarded aa a vital military otteuive aDd 

detenaive weapon, or even as a weapo11 in the f'irat place. Here I am 

remillded of a story in a very old book Oil cr)'ptography. The story is 

probably apocryphal, but it's a bit &DlWling, and I give it tor vbat it's 

worth. 

It aeeu tbat about two thoua&D4 years ago there lived a Persian 

queen Dllmd Semiramia 1 who took an active interest 1D cr;n>toloSJ. Whether 

it was becauae of that interest or for other UDDatur&l reuou, auch as 

cur1oait7 about what people call "aecre't611, the record 4oean •t s.,-1 but 

anyhow it ia reported that ahe mt with an untimly death. Presumably 

she went to Beaven, or perhaps to the otber place, but abe left 1Datructiom 

that her earthly remains were to be placed in a golden aarcopbagua w1th1D 

an 1mpoa1Dg •uaoleum OA the out11le of which, OA its frOAt atone wall, 

there was to be graven a ma1age, aaying: 

Stq', weary traveller! 

It thou art footsore, hungry, or in nee4 ot llODey--

Unloclt the riddle ot tbe cipber graven below, 

And you will be led to riche• beyond all dreau ot avarice! 

Below thia curioua inacriptiou. V&8 a cryptogram, a Jumble of letters 

without •aning or eveza pronounceab111 ty. For several huadrecl years the 

poaa1b111ty at sudden wealth served aa a lure to ~ experts who tried 

very hard to decipher the cryptogram. Thay were all without aucceaa, UDtil 
REF ID:A62Bji ~ 

spectacled aava.nt who, after VOl'king at tbe proJect tor a cau14erable 

length ot tim, solved the cipber, vhiah p.Ye b1a 4etailecl imltructiou 

tor t1D41ag a secret entr1 into tbe tCllb. When be got iuide, be fow:a4 

an inatructioa. to open the aarcophagua, but he ha4 to solve •neral mare 

crntcsrama the last ou ot vh1ch ~ lave iDTolvecl tiDlliDS tJae correct 

cambiDat1on to a 5-tumbl.er ccmbiD&tion lock--vho JmovaT Well, i. aolvecl 

tbat one too, atter a lot ~ vork, aa&t thia em.bled b1a to opm ti. 

aarcop!Jagua, 1Dll14e which be f'oUD4 a box. ID the 'box vu a •••age, thia 

time in plain languap, aD4 th1a ia vbat it said: 

o, thou vile and iU&tiable 11CUterl To d:latur'b theee pOOl" bonus 

It thou ba4 •at lear-4 aomthiDg more uaetul tba tbe art ot 

decipbering, 

Thou voul4•at not be tootaore, hU11&17, or ill nee4 ot llODeJ'I 

1 'm frank to cODf••• that -.D1' ti.Jes 4uriq 'llq 41-J9U' p:"eoccu,patioa 

felt tut good ol4 Queen SemirUli• Jmev what abe vu talkh11 about. Bovever, earning llOZl8J' 1• OAl7 a part ot the recompense tor working in the 

ceyptoloatc f1el4, an4 I hope tbat :moat ot ;you Will t1D4 out wooner or later 

vat aome ot these other reccmpeuea are aDll what 'Ule)' can w to J'OU• 

It Queen Semiramie thought tbu'e are other thillp to i.ra t!lat are 

lllON uetul than the art ot decipberSJac, I suppose ve •4 ave to agree, 'but 

we are warranted iD •&1'1DS1 at leut, tllat tl:Je:re illn •t ~ queat1aa about 

-3-
I 

REF ID : A62 eyal 

~ 

ua are 1nf'luance4 an4 atteated by it u I hope to ahav you ill a ffN m1Dutea. 

I will begin bJ reading from a source which 70u•U all recogn11.e--

TIME map.z1ne, the 1aaue ot 17 December 1945. I will :preface tbe reading 

by remiDd.1.Dg 70u that by that date World War II vu all over--or at least 

V-E and V-J 4"8 had beeu celebrated. acme mo.ntha betore. Som ot you may 

be old euouah to remember very clearl.y the lou4 clamor OD the part ot 

certain vociferous members ot CODgr"ela vho bacl tor year1 been 1D81at1Dg 

upon learning tbe reaaou why we ba4 been caught by aurpriae ill such a 

disastrous defeat as the Japuese ba4 1Dtl1ctecl upon us at Pearl. This clamor 

bad to be met, tar these CODgreSu.n contended that the truth could no longer 

be hushed up or held back because ot an alleged cont1Du1Dg need tor militar7 

aecrecy, u claimed by the Mministration aDd bf ~ Democratic ae.aa.tora 

and representatives. The var waa aver--vun•t itT--Republican ae:aatora aDll 

repreaentativea inliated. Tbere ba4 been 1nveat1pti0Il8--a half' 4ozen ot 

1' 

them, but all except one were 'l'OP SICRl"l'. The Republicau wanted, &Dd at .. ·' 

laat they got what they dea1recl--a gr&D4 tiuali!JoiAt Congreaaional IDveatigation which would. all be cOllpletel.y open to the public. lo more aecreta ! 

·' It waa spectacular! Kot ODl1' 414 the Coiagre••icmal Inquiry briug 1Ato the 

open eV817 detail and exhibit wacoverecl by ita own lengthy heariDp, but it 

alao cl1•cloaecl to Amrica aD4 to the vbole vorld everything that had 'been said 

and ahavn at all the preYiows Anr:f aD4 1f&'V7 1Avestigat1om. Moat ot the 

...,_ 
REF ID : A62 8'ii-

.._,. 

1Dto.rmat10A that was thua 411cloee4 bad been am much ot it was then still 

'?OP SD:Rm; 79t all ot these precious aecreta became matter& ot public 

information aa e r"!a'..'!l"t ot the CODgresaioual Investigation. 

There came a dlQ" in the Congreasioml. Hearillgs vben the Chief' of Statt 

ot tbe Uniteci States Artq at the time of the Pearl Harbor Attack, 5-star 

General George c. Mar1hall, wu cal.led to the wltneaa stand. Be testif''ied 

tor several long, lo.us daym, eight at them in all. 'l'Cftfard tbe e.ad ot the 

second day ot bis ordeal :be vaa questioned about a letter it had been 

rumored be'4 written to Governor Dewey in the Autumn of 1944-, duri;ag the 

Presidential C&lllJ8.1gn. 'rhe letter wu about codes. With troun face, 

General Marahall balked at disclosing the whole letter. Be plea4ed meat 

earnestly with the CommitteG not to force him to 4iaclose certain at it& 

content•, but to no avail. He ha4 to bow to the will ot the ma.Jori t;r of tbe 

Committee. Here's a picture of General Marshall aDd GoverDOr Dewey. I 

will now read trom TIME a bit of info.ration which may be new to ~ of 

my 11atenera, eapec1.al.l.y to those who were too ;young in December 1945 to be 

d:::w:ing into periocUcal literature or to be rea4ing any 1889• of the daiq 

newa,..per otber tba.D thOfle OD which the comics appear. 

Said TIMB, &D4 I quote: 

"U.S. citizen• discoverecl lut week that perhapa their mo1t 

potent secret weapon of World War II was not radar, not tbe VT 

tuae, not the atom bomb, but a harmleea little achi.De vbicb 

... 5 ... 
REF ID : A62 t\li-

.._. 

crntograpber• Mil iaiutatiragly ccmatructecl in a hidden room 1D 

Waahiugtcm. With this mch1:aie, built after 1Ml'• ot trial and error, 

ot iDf'erence aDd deduction, crntographera ha4 duplicated the decoding 

devices used in Tokyo. Teati.me>A1 before the Pearl Barbor CCllllli ttee 

bad alrelldy shown that the •chiJUI known aa 'Magic• vu in use long 

before Dec•ber 7, 1941, amt ha4 given aapl.e warning of the Jap11 1 

sneak attack it on:cy U.S. 'bru• bate bad. been amrt eDOUgb to 

realize it. Bow, General Maraball continuecl the ator1 ot 'Magic'•' 

magic. 

1. "It hll4 enabled a relatively •all u.s. Paree to intercept a Jap invasion fleet, viD a decisive victory in the lattl.e ot the 

Coral Sea, thus .. vi.Dg Australia &D4 Nev ZealaD4. 

2. "It had giveD. t!Je U.S. full advance 1.Dtoration on the 

size of the Jap forces a4V8.llc1Dg cm Midway, enabled our laV7 to concentrate ahips which otherwise might bave been 3,8H mile• away, thus 

aet up an ambush which proved to be the turni.D.g-point 'Yict017 ot tbe 

Pacific var, 

3. "It ha4 directed U .s. aubm.rinea unerriDgly to the •ea 

lanes wbere Japanese CODV019 w°'1ld be puaing. 

4. "By decoding •••ase• from Japa.n'• Am.buaa4or Oahima 1D 

BerliD, often reporting 1Dtervieva v1th Bitler, it had given our torcea 

1nvaluab1e information on Germn var pl.au." Ji:D4 quote • 

-6-
REF ID:A62. 

TIME goea on to give more 4et&U. ot that story, to vbich I ay later 

return but I cu •t leave thia citation ot vbat crntology did towvd. our 

winning ot Worl4 War II without tell1.ng JOU that the account given by 

TIME of tbe achin-emnta ot MAGIC aalr.e• it appear tbat all the eecret 

intelligence gained trOlll our readillg Japanese •••age• was obtained by 

usin8 that "harmleaa little mchine" which TIMJI: •&14 vas uaed ill 'l'oqo by 

the Japanese Foreign Oftice. I muat correct tbat error by telliDg you tbat 

tbe secret intornation we obtai-4 that way W little to do with thoae 

partiODS ot the MAGIC naterial which e:aabled our lavy to will such apectacular battles aa those ot the Coral Sea aDd Midway, aa1 to waylaf Japanese 

convoys. The naval. parts of MAGIC vere nearly all o'btai.Ded tram Japanese 

naval messages by our ovn very 1ngen10WI U.S. lfavy cryptanaJyate. At that 

time, I my tell those ot you wbo are uev, that the Arrq aD4 Davy ba4 

separate but cooperatins ceyptologic agenci•• an4 activitie•; the United 

State1 Air Force vu not ~t in exi1tence aa an autoDomoul and aeparate 

canponent ot the Armed Force1, and vark on Japanese, Oerm.n, aD4 Italian 

air torce ccmunicatiODS wu done by Army cryptaMl)19t1 admirably aaaiated 

by personnel. ot vbat vu then known u the Army Air Corpa. 

It 1• hardly neceasar7 to tell you hov caretully the MAGIC ot World 

War II vu guarded before, during, and atter the war \Ultll the Con,gre1aional 

Inquiry brought most of it out 1n the open. Some re-.1.ni.Dg part• of it are 

still very caretully guarded. Even the tact at the exiatence ot MAllIC vu 

-7-
REF ID : A62 E}A1 

.. 

kDovA to onl7 a very tew peraou at the tu. ot harl Barbor--&DCl that is 

an important elemnt in any attempt to explaiA w~ we were caught ~ 

eurprlae by the Japueae at Peu'l Barbor in a d.evutating attack that 

crippled. our Davy for DaZQ" ll!Olltha. Let me reacl a bit tram :page 26lot the 

Report ot the MaJorit7 ot the Joint Congreaaioml. Investigation ot the 

attack: 

"The Magic intelligence vu pre-eminently important &Diil tbe 

neceaait7 tor keeping it ccmf'14enti&l cannot be overeati-.ted. 

However, so cloaely held aD4 top aecret vu this 1Atell1gence that 

it appear• that the tact that tbe Japanese cedes hll4 been broke.a. -

was regarded as of llOl'e importance tlwl tbe inf'or•tian obta1De4 

trm decoded traffic." 

TIME aaya, iD. coa.nection with tbis phaae ot the stor7 ot Magic 4uring 

World War II I 

"So pr1celes• a poaeesaion wu MAGIC that the u.s. high cgmmp'Qd 

lived. iD comtant tear that the Japa woul4 discover the secret, 

change tbeir co4e mchiner7, force U.S. cr)'ptograpber1 to atart all 

over a.pin." 

Itov I 4m't want to over-empbuize the impcrt&Dce ot ca1111nn1catiou 

intelligence 1D Worl4 War II, but I th1Ak it varrante4 to read a bit more 

of what 1• ea14 about 1ta 1.llpartuce iD. tlJe Report ot the Majority. The 

folloviD& 1• trCD. p. 2321 

-8-
REF ID:A62. 

". . • all v1 tneaaea tua111ar vi th MAGIC •ter1al throughout the 

war have testified tbat it contributed enormoualy to the 4eteat of the 

eneJQ", greatly shortened the var, an4 aave4 Dm.QJ thouaan4a of livea." 

Oeneral Chamberlin, vho vu General MacArthur •a operationa ott1cer, or 

G-3, throughout the war 1D tbe Pacific, ha.a written: ''The 1Dtorat1on G-2 

that ia, the intelligence eta.ff', gave me in the Pacific Theater al.oDe 

aaved us Jll&D1' thousaa.ds ot 11 vea aD4 ehortenecl tbe war by DO lea a than two 

;years." We can•t put a dollar-and-cents value on what our po9&e&a1on ot 

COMIIR meant in the wq of aav1Dg lives; but we can D&1re a dollar-aud ... centa 

e1timate ot Ybat cC11111UDicat1om intelligence meant by shortening the war b;y 

tvo )'ears, and the result ot that estimate is th&t it appear• that $1.111 

a pent tor t)lat 1ort ot intelligence wu worth $1, '"'' spent tor other military 

activities and 1aterialll. 

In ahart, vben our cQ!ll!D8-Ddera ha4 tbat kia4 o.t intelligence in World 

War II they vere abl.e to put what a.U forces the;y bad at tbe right place, 

at the right time. But when tbe;y d14n't have it--am thia bappeuad, too,--

their torcea often toolt a beatil.lg. X.ter on we'll note iutaDces of each 

type. 

I hope I've not tried your patieD.Ce by auch a lengthy preface to the 

real aubatance ot thia aeries ot lecturea, so let's get down to brass tacks. 

For those ot you who come to the aubJect ot cryptoloa for the tirat tu. 1 a 

few detinitiona will be uaetul, in order that vbat I shall be talking about 

-9-
REF ID : A62 til 

,.,. 

will be underetood without que1t1on. AgNement on basic terminology ia 

alvaya desirable in tackling &Dy' new subject. In giving you the def'initions there rray be a bit of repetition because we will be looking at the same 

terms from somewhat different &Dgl.es. 

First, then, what is cryptologyt Brief'ly, we my 4et1ne it as the 

doctrine, theory, or branch of knowledge which treats or hidden, disguised, 

or secret communications. You won •t find the word cryptology in a small 

dictionary. Even Webster's Unabridged defines it merely as "secret or 

enignatical language"; aud iD its "Addenda Section", which presumably 

contains new or recently-coined words, it is de1"1.ne4 merely aa "the study 

of cryptography". Neither of these detiJlitions is broad nor specific 

enough for thoae who are going to delve somewhat deeply into thia science. 

Cryptology has two main branches J the first is cryptography 1 or, very 

briefly, the acience of preparing secret comnunicationa; aD4 the aecond 18 

crypt•n•lysia, or the science or aoiving secret communicationa. Let•s 

take up cryptography tirat, becauae aa a procedure it logically precedes 

cryp"ttenelysis: before solving anything there must be aomething to solve. 

Cryptography ia that branch of cryptology which deals with the various 

means, method•, devices, and machines tor converting messages in orcU.m.ry 1 

or what we call. plain l&Dguage, into aecret language, or what we call cryptograms. Here•a a picture o-r one ot the JD011t f'amous cryptograms 1n history. 

It was the sol.ution of thia cryptogram which resulted in briQging America 

-l.9-
REF ID : A62 Bjj. 

.., 

into World War I on the •14• of the Allie• on 6 April 19171 Just about aix 

weeks after it vu solved. I'll tell 70u about it later 1D tb1a series. 

Cryptogra~ also includes the business of reconverting the crn>tasrams 

into their original plain-language torm, by a direct reversal of the steps 

followed in the original trana£ormat1on. Thia impliea that the persona 

involved in both of these bits of business, those at the e:acipbering &Dd 

sending end, and those at the receiving and decipherillg end, have some sort 

of understamiing as to what procedures, devices, ar:i4 so ou, will be used 

and exactly hav--.down to the very laat detail. The what and the how ot tbe 

bus ineBB conati tutea What is generally referred to &8 tbe m • The key my 

consiat of a set ot rules, alphabets, procedures, and so on; it may also 

consist ot an ordinary book which is used as a source ot keya; or it 'ay 

be a specialized book, called a code book. 'l'hat cryptogram I Just showed 

you waa made by using a book--a GerlBll codebook. 

To encrypt, is to convert or tranaform a plain-text •••age into a 

cryptogram by follovi.Dg certain rules, steps, or processes cQD8titutiJlg the 

key or keys and agreed upon in advance bf the correapondenta, or furnished 

them by higher author! ty. 

To decrypt is to reconvert or to trwf'ora a cr;yptogram into the 

original equivalent plain-text message by a direct reversal ot the encrntiDS 

procesa 11 that 1s 11 by applying to tbe crntoSl"• the key or keye 11 usual.q ill a 

reverse order, employed in producing the cryptogram. 

-U-
REF ID:A62. 

A per1on who encr71>ta aad decrnta maaapa °b7 having iA hia possession 

the .necessary- ke711, is calle4 a cmt91Fa:pher, ar a crutovalthi$. clerk. 

dea1gaated as coclea and c1Jlbers. Such mew are uaed tor either a.r both ot 

two purposeaz (l) secrecy, a.ad (2) econ~. Secrec7 us~ 1a tar more 

possible to caabine secrecy amt economy i!1 a sixt.gle •JSt.tw.. PersODI 

technicall1 UDacquaillted with cryptolc otte.c. talk about "cipher code&'', 

a term which I suppose came into wse to dittereo.tiate the term "code" u 

used in ceyptol.ogy f'rom the same tera aa used iD. other ccxmotationa, as, 

for example, tbe Dapoleo.nic Code, a trattic cCJde, a buildlng code, a code 

Of ethics, am so oo. Saw, in cryptology, there is no such thing as a. 

"cipher code". There are codes and there are ciJ>b!rs, and we misht a.a well 

learn right oft the clitf'erencea between them so that we get tbea atraigbteDllCl 

out in our minda before proceeding :further. 

In cipber1, or in cipher syatema, cr;yptop•ams are produced by applyi:ac 

the 1•ryptasraphic treatment to i.Qalivid'Ual letterw of the plain-text meaeagea, 

where30, in cod.ea, or lu. code systema, crwtograma are produced by applyiDg 

the cryp'togt'apJl1c treatmeut se.ueraJ.l¥ to entire wcrds, phrases, and 

sentences of the plain-text mesaqea. Mare 3pecialize4 meaniup ot the terms 

will be expl.a.1.'led in detail later but in a moment I• 11 ahaw l'OU an example ot 

I 

I 

• crntogram 1n cipher and one 1D code I 

-12-
REF ID:A62~ 

-

A cryptogram. produced b)" ~ ot a cipher a;vatem ia •aid to be in 

cipher mad 11 called a ci:pber ••aye, or aomet1mea, simply, a cit>b!}'. 

The act or operatiOD of encr)"pting a cipher mssage 1a calle4 enc1pb!riy, 

an4 the enc1pberecl version ot tbe plain text, as well u tbe act ar proce1a 

itaelt, i• otteu referred to as the uc1pl!ermnt. A cryptographic clerk who 

perform the process serves aa azi enciprer. The correapoa41ng terms appl1-

cable to 4ec:rnt1Di cip:ber meaaa.sea are 4ec1pheriy, decipr•nt, and deciprer. 

A cr)'Ptogram produced by means at a code ayata ia said to be 1D code, 

am is calle4 a code ma11ye. The text ot the cr1J)togram is reterre4 to aa 

code text. Thia act or opel'ation of encrn>tiDS is cal.led encodiDI, aD4 the 

encoded veraion ot the plain te~, as well u the act or process it&elt, 1a 

referred to as the encod~~. 'rhe clerk who pertorma tl:le process serves as 

an encoder. Tbe correspoDdiDg terms applicable to the decrypt1Da ot code 

measages are 4eco4iy, 4ecodemer&t, amt decoder. A clerk who ucodea aD4 

decodes maasagea b)" having iD his possession tbe pertiMnt cocla booka 1• 

e:.llecl a code clerk. 

'l'ecbnically, there a.re only two distinctly different t;ypes ot treatment 

which ay be applied to vritten plain text to convert it illto a cipher, yielcl1ng tvo different clasae1 ot cipbera. Io the first, called. tranapc?81tion, 

the letters ot the plaiD text retaizi their original identities &ad merely 

umergo some cl:la.Dge in their relative positiona, with the result that the 

origiDal text becomes unintelligible. Here's an authentic example ot a 

-13 .. 
REF ID:A62. 

tranapoa1t1on cipber; I call it autmDtic becauae it vu amt to Preaident 

Rooeevel.t aD4 the Secret, Service uMd • to 4ec1pber it. Imagine rq 

chagrin wbeD I Md to report that it •&18 "Did 7QU ever bite a lemon!" ID 

the secoml, called aubstitutton, the lattera ot the plain text retain tuir 

orig:l.Dal relative poaitiona but are replaced by other letter• vith ditterat 

sound values, b7 symbol.a ot acme aort ao that the original. text becamea 

UDi.DtelliSible. 

lfoboq will quarrel with you very bard it you ¥Uh to aq that a code 

s19tml 11 a.othing but a •pec1al.1uc1 tarm or aubet1tut1cm; but it's best to 

use the vord cede vben a co4e book ii 1Dvo1ve4, and to uae aubatitutiou cipher 

when a literal 171tem ot su'batitutiOD 1a usecl. 

It 1• posaible to encrnt a massage by a aubstituticm •thacl &ml tbtlD 

to appl.J' a tranapoaitioa •thod to the substitution text, or vice veraa. 

CcmbiDecl traupos1t1on-au'bat1tutian ciphers 4o not fona a th1r4 clua ot 

cipherai t!le7 are onq occ:uioaaJJ:y ancowitered :1n mil1"taz7 crntcsr•Pl7· 

Appl.JiD& a cipher 'to code croupa ia a ver7 trequently-uae4 p-oce4ure and 

ve •u •• cue• of that too. 

Bere*a an example of a aubatitution cipller, aD4 a veey 11mple oae. 

It ..,.. toum on a GerDaD •w 1A Wcrl4 War II. Here'• the c1pber alpbabet; 

here'• the pla1D text which happmecl to be 1D Germn; and here'• the cipber 

text or encip;ber ment . 

-14-
REF ID:A628 • 

..... 

NOW' tor UL example ot a c:rntosr• 1D code. Here'• a plaill-text meen.ge 

in the handvritiq ot Preeiclent WUaca., to hi.a 1pec1al em111ary 1D Load.on, 

Colonel Bouae. Here'a tbe aeyptogram after tbe plain text vu encocled, by 

Mrs. Wilsonr 'l'be President then bimelt t1'.Jj)ll4 out the ti.Dal meeaage Oil bia 

awn typewriter, tor tranenU.asion by the Department ot State. It would appear 

that President Wilson lacked conf'idence in the •ecurity ot tbe ~t ot 

State's mthoda--&Dd maybe with good reason, u M1' be •HA in the toll.owiD& 

extract from a letter dated l~ September 1914 :f'rom the Pre11clent to Ambuaadcxr 

Page in London: "We have for same time been tr;yiDg to trace the J.eaU, tor 

they bave occurred frequently, aD4 we ue now convinced that our code is 1A 

posqesaion ot para0ll6 at interme4iary points. 'We are SoiD& to take thorou&h· 

going meaaurea." Perhaps one ot tbe meuur• was that the Preaident sot 

bimelf' a code of bis OW'D. I JDW1t t'ollaw this up •om ~. 

A cipher device ia a rel&ti~ •impJ.e mechallical cootrivauce tar 

the tingera, as tor example, a device with ccmcentric ri.Dp of a.lphabeta, 

man~ paweredr Bere•s an exaaple--a cipher device Yith eucb ri.Dp. I'll 

tell you about it later. A cipber -.chine is a :relatively complex apparatua 

or mechanism for encipbermant am 4ec1pbermlllt, uauall.y equippe4 with a tn--

cryptology 1 followixag the tread in -.chatdzat1on a.ad autanaticm 1A other 

fields, now deals larpl.J' with cipher m.chiMa, sane highly complicated. Here'• 

a picture of a modern cipher mchiue Yitb ketboard a.ad print~ meohanfa•. 

-15· 
REF ID:A62. 

One ot the expresaiOllll which uninformed laymen uae but which you must 

never use 1s "~ German code" 1 ar "~ Japanese cede" 1 or "~ Davy cipher", 

and the like. When ;you hear tbie sort ot express ion JOU my put the &p!aker 

down at once as a novice. There are literally hundreds of 41ff'erent coclea 

and cipher• in 11multaneous use by every large au4 important gover.m.nt or 

service, each suited to a special purpose; or where there is a multiplicity 

or s)"Stems ot the same general :nature, the obJect 11 to prevent a great deal 

of traffic being encrn>ted in the aam key, thus overloading tbe ayatem aD4 

making it vulnerable to attack by mathod• and pl'OCeclurea to be ment10Ded 1D 

broad terms in a tw momenta • 

'?he need far secrecy in the comuct of important affairs has been 

recognized from time imine.:m"ial. In the case ot diplomacy and organized 

warfare thi• need is especially iJllROl"t&nt in rep.rd to co11111a1catiows. However, when such commuD1cat1ona are tranami tted by electrical •a.ue, they cu 

be heard or, aa we say, 1nterceJ?te4, and copied by unauthorize4 peraoma, 

~wa.ll.y referrecl to collect1vel.J a• tbe eD!!aY· The protection reaultiug trc:a 

all measures designed to deny to the enemy 1.atormation ot value which 111&1' be 

derived frau tbe interception and st\ldy ot such commun1ca.t1ou 111 calle4 

camunication security, or, tor short, COMSPX:. 

ID theory 1 any cryptoe;ratem except one, to be 41acus•ed 1n due time 1 

can be attacked and "broke11" 1 1.e. 1 solved, it enough time, labor,, and skill 

are devoted to it, and if the volume of traffic in that ayatem 11 large 

-J.6-
REF ID:A62. 

enough. This can be done even 11' the general system and tbe apecif'ie key 

are u:ukn~m at the start. You will remember that I pre.faced my &tatement 

that any cryptosystem can be solved by saying '' ~ .1 theory", because in 

military operatio::is theoretical rules usually give way to practical cona1derat1o..'lS. 

That branch of cryptology w.hicl: deals vi th the principles, method•, and 

means employed 1..l the solution or analytis of crypto1ystems is ce.lled 

cr:YJ,1ta.na.lytlcs. The stc]:)s and. operations performed in applyillg the principle• 

of' crypt~ic& conDtitute cry;ptanalysiE.. To crYptanal.yze a crY,Ptogram ia 

to .solve it by cryptanalysis. A person skilled in the art or crnitanoJ.y&is 

is called a crni.a.na.l.yst 1 and a clerk Who O.SbiStS in 3UCb work 1.S called & 

cry;gtanal.ltic clerk. 

Iu.f'ormatiOll derivecl f'rom the organized interception, study, and analysis 

o£ the eJlemy's co:umunications is called comunication in'tflligence, or, tor 

abort, COMilfr. Let us take care:tul. note that COMmT and COIE~ deal witb 

com:mm1cat1ons. Although no phenomenon is more familiar to us tbau tba.t ot 

colilll1\Ulication, the fact at the matter is that this magic word means mariy 

things to lllllJlY' people. A def'in:tticn of communication that is broad enough 

for our purposes would be that coi:umm1cat1on deals with intelligent measagea 

exclml)3ed between intelligent beings. This implies that human 

beings, aud human operators are involved in the preparation., encryption, 

transm.Lssloo, reception., decryption, and recording at messages which at aome 

•taB• or 1tage1 are ill written form ar¥l in acne •ta&e or stage• are 1A 

-17-
REF ID : A62 8A1 

., 

electrical form u a:tgnal• of oae aort or another. But in recmat yeara 

there have cane into prominence aD4 im;parte.D.ce electrical a1pal.a which are 

not of the a art I've just iD41catecl. TbeJ do not ~ "mangea" in the 

usual sense or the wcn-d; they- do not convey fran one bumn being to another 

an intelligible sequence Of words am an intellisible aense. I reter here 

to electrical or electronic signals such as are em:pl()Jed in bom~ng or 

directional beacons, in radar, in telematering or recording 4ata of an eJectr.kal aelectronic .aature at a distance 1 &ad •o on. In:f'ormtian obtaiDed 1'1'om a study 

of enemy" electronic emissions ot theae aorte iB called electronic 1ntell1pnce, 

or, for short, ELINT. The particular ar apec.ialised atwly of enemy radar 

signals is called RADID'r. All theae, COMm, ELINT, RADM canprise SIGillr, 

that is, •ipl intellipnce. Ceypto1ogr 18 the science which is concermd 

with all these branches ot aecret aignalling. -

In tb1s aeries of lectures we •hall be concermd ~ witb CCICSD: and 

CCllIH'r, leaving tor others and tar ather tu.a tbe aubJecta of ELm, RADillT, 

and so on. Thia met1111 that we •hall deal with CClllllUDie&tioa.a or ••!!P•· 

Camunic&tiou 'lll&Y be conducted 'b;y' eny means auaceptible ot ultiate 

interpretation by one of the five awn, but tboee lllOSt cormop1y uae4 are 

eeei.ag am hearing. Aside tram the uae of ai.mple vi8ual am auditory 

signals ~ar commm1cation <Ner relative~ short diat&Dcea, tbe usual •tbocl 

of ccmmm'JcatiOQ between ar among individuals •ep&rate4 from one another by 

relatively long distances iDVolvea, at one stage or anotber, the act ot 

wr1t!Qg or of apeakilig over a telephone .. 

-J.6-
REF ID:A62B8 

Privac1' ~ 1ecrecy in c011111.U11icatiou by telephone can be obtained by 

us:lng equipment which af'fecta the electrical currents involved in telephODJ1 

ao tbat the conversationa can be umeratoocl ~ 'bJ' persons provided with 

auitable equipment properly arrupd tor the purpose. 'l'he aame thing is true 

in the case of f'acaimile tranamission (i.e., the electrical tralllmisai~ ot 

wd1nary writing, pictures, drawinga, maps). Iver& today there a.re already 

simple fQ?'m$ ot enciphered television trausm1aa10Dll. Enciphered facsimil.e 

ia called CD'AXJ enciphered telepho~, CIPBONYJ and enciphered televiai011, 

CIVISIOif. Bowever, these lectures will not deal with these electrically am 

crypt&nal)'tically more complex torm ot cryptology. We shall 1ticlt to 

encipheracl or encrypted writing-·vbich vill be bard eriougb tor moat of us. 

Writing m;y be either viaible or invisible. In the former, the 

characters ar~ 1.nacribed with ordinar7 writing materials aD4 can be aeen 

with the nakec1 eye; in the latter~ the characters are 1nacr1bed bJ meua or 

Mtho4e which Mke tbe writing invisible to the naked eye. Invisible writiaJg 

can be :pre:pared with certain chemicals called l)'Jllpathetic or secret 1Dks 1 

and 1D order to "develop" such vr1t1.Dg1 that 1s 1 make it v1•1ble1 specia.l 

pl'oce•sea !llU8t U9uall.7 be applied. Bere•a an interesting uaurpl.e--the 

developecl aecret-ink meaaage that figured 1n an $81,f.118.,818 suit van by two 

American fil"lll ap1mt the German GoYermier&t after World War I sabotage was 

proved. There are alao metho4s ot pro4ucing writins which 1a invisible 

to the naked. e;ye becauae the character• are ot micromcop1c size, tl1'1s 

·19-
REF ID:A6211il 

..,. 

requiring apecial micra1copic and photographic apparatus to enlarge such 

writing aa to make it visible to the D&ted e19. Here'• an example--& code 

meaaap in a space not much larger than the bead ot a pin. A siulple 

definition ot aecret writing would be to aay ti.t it ccmpriaea inviaible 

writing and unintelligible Visible writing. 

'l'here is one addit10Dal piece ot "buic intonation which it 111 wise 

to call to your attention bei"ore ve proceed much further, aD4 I'll begin by 

stating that the greatest and tbe ID09t ponrtul 1Datrumnt or weapoA ever 

dependence upon his own enviromant is the wm.pon ot literacy--a mutery ot 

reading and writiDgJ aDd the moat important invent10ll, the eat that Dmde the 

weapon of literacy E&ctical, vu tbe invention ot the al:pbebet. It is 

therefore a rather atriking anaD&l.y that we should DOii cane to tbe study 

ot another veapon--a counter-weapcm to tbe veapcm ot literacy-·tbe weapon 

of secl'!CY, the basic intent of which ia to thwart tbe veapoa that man 

stru.ggled ao long to farge. Secrecy 1a applied to DBke writing mare ditticul.t 

aod tbe rea41DS of tbe writing veq 4itticul.t, if not imjx)llaible. 

Perhaps this is a good place to do a bit ot tbeori&iD& about this matter 

at secrecy am what it implies. 

Every person who e.ucipbel'e a piece ot writing, a -..age, ar a text ot 

any kind, fer the purpose of hidi.Ag s0111tthing ar a£ Jr.eepiag aaaethi.Dg aecret, 

does so with the i4ea that aome other peraw, removed traa him in distance, 

-2•-
REF ID:A62.1 ...... 

or tu., er both, is 1Dten4e4 to decipher the writing or •aaage am thua 

uncover the secret wb1cb wu ao h1c1den. A peraon ._.,posses• a certain 

piece ot Jmowle4ge which he does not wish to torget but which he ia neverthelesa UDWilliDS to cCll'Jllit to open writing, and therefore be -.y Jot it 

down in cryptic form tor hi.melt to decipher later 1 when er if the 1Df'ormt1on 1• neeclecl. The moat v14el.J' JmOVD example ot auch a cryptogram is 

tounA in Edgar Wan Poe'• rommtic tale 'the Ool4 pug. 'l'h&t aart of usage 

of cryptoSl"aPb7, however, is unueU&l.. ':here are alao examples ot tbe use 

of cipher writing to eatabliah priorit7 of discoveey, as 414 the utrOUOMr• 

Galileo an4 Burgens. Here 1 a a· slide which shows both examples. I suppoae 

I ahoul.4 at leut mntiOD another sort of c17JYt1c writixlg f'amoua 1D literary 

bi1tor7, the diaries of peraou such u Samuel Pepys mad William BJ'l"d, These 

are ccwenn17 repnled u being "in cipher", but tmy were actually written 

1n a llDl"e or lee• Fivate 1hortban4 a.n4 ca.n eaail.J' be read. withou.t the help 

of cr~i•. Here •a a picture ~ a pqe of Pepys diarf. 

Now there can be no logical reuon, point, ~ purpose in taking the 

time u4 troubl.e to encipher mqtb.1Dg unleaa it 1• expecte4 tbat acme other 

peraon 1a to 4ecipber the cipher some time in the tuture. 'l'bia :meua that 

there :muet exiat ame very direct, cl-.r-cut aa4 ummbiguoua relatiouhip 

between the enciphering anc1 c.\ecipbering operat1Cll8. Juat what such a relation-

•hip involve• will be dealt With later but at thi• momeDt all that it 1a 

nece••ar.Y' to aay ia that in enciphering tllere muat be rule• that govern or 

-21-
REF ID : A62 t}6J. 

.., 

control the operatiows, tbat these rules must admit or no uncertainty or 

ambiguity and tat the7 must be susceptible at being applied with undeviating 

precision, otberviae it will be ditticuJ.t or parbapa impoes1ble tor the 

decipherer to obtain the correct answer when he reverses tbe proceaaea or 

steps followecl in the encipberment. 'l'hi• -.., be a good plac:e to point out 

that a valid or authentic cryptenal)"tic eolutiOll cannot be conaid.ered as 

being merely what tbe cr~t think.8 or &IQ'& he thiW tbe Cl'JP'togr&m 

meana, nor doea the aolution represent an opinioo. ot the ceyp~t. 

Solutions are val.id only' inlotar u tbey are objective and susceptible or 

demonstration or proof' empl.o;yi.Dg ec1ent1f1cally acceptab1e •thoda or procedures. It should barclly be necesaary to indicate that tbe validity ot 

the results achieved bf' cr~ic studies ot authentic cryptograms 

reats upon the •a.me sure aIK1 vell-establ.iahed •cientitic :toundatio:aa, aDd 

are reacbed 07 the Balle sort at logic as are the d1acover1e• 1 results, or 

"a:aavers" achieved 07 aq other sc1ent1t1c studies, namely, observation, 

hn>othesia, deduction, inducticm, and cont'irmtory experiment. Implled iD 

what I have Just said ia tbe tac:Ltq uaderatood and now rarely explicitly 

atated assumption that tvo, or more, eplly competent and, 11' necessary, 

speci&lly qualified investigators, each Vcxt'kiDg independently upon the SUie 

material, will achieve identical or pract1cal.J3 1clent1cal resUlta. 

Cryptology ia usually and properly conaidered to be a branch of matbeatica, although Francis !aeon considered it also a branch of grammar aDd 

-22-
REF ID : A62 t}A1 

~ 

wbat we nov call 11.Dguiatica • Matbeatical aDd etatiatical cons ideratio.na 

plq an ever-increasing and prominent role in practical ceyptology, but don't 

let -rq statement ot thia point f'rigbten those or tau. who bave not bad much 

formal instruction in these subJecta. We have excell.mit cryptologists who 

have never studied more tban arithmetic, and &Olll!t of our beat one• vould. 

hide if you were to go searching for matbem.ticiana around here. What is 

needed is the ability to reaaOll logic~ as tbe -.tbenatician sanetU.s 

does aM. this ability is toun4 in the moat curious aorta at persona a.n4 

places. So thoee ot you who are trightet&ed by the words mathematics aDd 

statistics take heart--1ou •re not nearly so bad off as you DJa1 tear. 

»ut now to return to the min theme as to the place mathema.tica occupiea 

in cryptology, let me se,y tmt Just as the Bolution of mathematical probl.ema 

leaves no room far tbe exercise ot divination or other Dl)'lterioua mental or 

psychic pawera 1 ao a valid aolut1on to a cryptogram mu.st leave no room tar 

tbe exercise ot auch powers. In cryptologic science there 1a one and onl1' 

one valid solution to a cryptogram, Ju.at as there ia but one correct solution 

or "solution aet" to any problem iJ.l -.them.tics. But perhaps I tve already 

dvel.t on this point too longJ 1D a:r:q case, we'll caae be.ck. to it later, vbeA 

we cCCle to look at certain type• or what we may call puudo-cipbers. 

In the uext lecture 1 •m going to give you a brief" aJ.impl5e 1.Jlto the background or biatary ot cryptology 1 which makes a long aD4 interesting atory that 

bas oever been told accurately am in detail. The history ot comntnn:lcationa 

-23-
aecurity, that 18 1 ot cryptcsraphy, aD4 the history ot ccmun1cat1ona 

ot 

the aame co1n1 de1erve detailed treatment but I am dubioua tba.t tb18 eort 

or h1stat'y will ever be written because Of the curtain of aecrecy and 

silence which officially surround.a the whole f'1el4 ot cryptology. 

Authentic iDtOl"mtion on tba background and 4eve1o,inent of theae: vital 

atters having to do with the security ot a nation 111 UDl!ersta.Dd.ably quite 

aparse, 

But in the succeeding lectures I'll try my best to give you authentic 

inf'ormation, and where there's conjecture or doubt I'll so indicate. I must 

add, however, tbat in this aeries I'm going to have to cnit many highlyintereeting episodes and bits of inf'ormation not only because these lectures 

are of l.ow clus1t1cation but alao because wu won't aDd can't go beyoml a 

certain period in crn>tologic history tor security c0Zl814erations. Nevertbeless, I hope you von•t be disappointed and that you'll learn certain things 

at great intere1t and importance, tbinp to remember it you viah to make 

cryptology your voeat1on in lite, 

' . 

" ' '