REF ID:A70310 

NATIONAL SECURITY AGENCY 

WASHINGTON 25, D. C. 

Jh;Jor Oe1•ral J'raDk J. ltoner, USA, Ret .. 

Variall Allaooiate• 

611 Jluulen W&J 

1alo Alto, California 

Jlear J'r&nk I 

S.re ia tbe tollov-up on rq utter of l April in coimeot1on 

vith the crnto117etea )'Oil Mnt • via Colonel Brown nce11t17. As t iAtUcatecl we VOUl.4 1n 111',/ letter, w pve 'the thing a prett7 

thorough •cru.tiu¥. 

Vlltortunateq, the a;r•teJa de•fcmd 'b7 Mr. lmith doe• not 

••l1f¥ uq crntosraphio principle• AOt ·~ 1mawn to WI, 

u4 1t ba.1 certain aJor cliadvantage•, cam.pu:ecl w ayatema ill 

ourX1tllt WM. Although the cOlllbinaticm r4 buio principle• above 

• kMn and facile miDd, u4 a tla:lr tor aqptasraphia mn1pll&t1on 

on the part ~the dllsipar, MVeral deterrent• to it• operational 

r .. tb:ll1't1', tor our parpoeea, m7 be cited. '118 ilaherent require .. Milt '\bat -.ch cipher ••H&e be tvice the lJm&th of the correapom. .. 1111 plain luaUllP 1• u unecar.\Ollical feature ror larp volume trattio. 

!be taot that a •iDCle di•erepanq- between tl:le c:orreat cipher tu.t 

aD4 the "VWr•ion rec91ved. J9¥ cttect the 1ntell181'bil1ty at the :re-

•1J:de1' ot the ...... alao 1nt.roduee• a Mahl¥ undeeinble factor. 

lt 1• nc:qpi1M4 that nch error• ~ be con-eoted ~41)¥ •nouch 

lD bud. O)il8rat1on ot wch a qat.•J boweVel", in eJActro-•chanieal ad 

•lectroidc &daptatiOD9, preHnt criteria require that autouatic equ.1plllblt be p1ra1tte4 to operate um.ttende4, without the 11kel1bood ot 

ur:qre4ictab]¥ la.re st:rwtcbe• ot unintell181'ble plain text rellUl.th:tg .. I t.el 1u.re that )'OUr J.ona background ot practical experience 1u 

'*1.ect.rical ocmmlDiaation technoloO will Mrnt to corroborate tba 

...,..1. w llQ" upm the 41-.dvuteae• or 11r. 8m1th' • •:ratem tor 

lfdten11ve ott1c1al telecoam.m1cat10DB. 

it. i• 11rtere1t1Q1 to IJOte the thorough ~•1•1 'b7 tha author• 

Of tm 'brochure, of ti. potential WMlme•Ua ot thia 1J71J'temJ theiX' i*pllllhnt~ aat1.ce1'¥94 .thoda for awrttng tn.H wakne••• repre· tn.t & c~llda'ble &Chi9'9-.ant. I truat 1ou Vill •P1"9 .. our 

appnC!iation to Mr. laith, and to hi• UllOCi&te JCr,. lAlvi•, f'o:r their 

)6tr1ot1c utereat and expenditure ot t1- an4 ettort in tb11 natter. 

At the aoMnt I aa recoverillg tl'Clll a llinor heart at.tack but 

tbey put • in the bo•pital mverthelAI••, wbere X have aJ.r.c\Y been 

@'pp roved for Release by NSA on 11-06-2013 pursuantto E .0. 1352a 
REF ID:A70310 

tor 9"r tvo web. lovever, I'• aldng &004. ~·· ud •hollld. be 

out at bent 1A a couple or hwx1red ,ura -- at lu.a't it vUl aeem that 

l.oila· 

------------------------·---- -- -·--
REF ID:A703IO 

._,or ClenenJ. huk 11. etomr, tBA, ltt4. 

Yariul Maoctatea 

Sll.luaRn"-¥ 

ftalo Alto, Calitomi& 

Dlar bankt 

I .. bighl¥ pl.-..4 w Jan a tel.eJ;tlcme c&ll f'Z'Cml Coloml ll"oll'A 

u4 '° mv. D1W about ,ou. aa4 llrs. ltoaer, tor I ba4 be1r1 _.r1.na 

ll:bolt. ~)'OU. IU."e lm4. 11hat 1Ql &re- DOV 4oinl• 

'.Ida i.tter v!ll be 'but a brief acJmovl.edpn.t ot l'ttee1pt or 

JOllr 

~ 

:i.tter u4 its 11Mt1-\lra 4eal1Da VS.th a ~phic 1Ptem 

'by 11r. Jlowa.rd •· 1111.tth ot ¥OU1" ar;an1•t1ou. 

'lcu flatter • b1' )'OUJ" cbaraotel'1•:t1on ot st ~nt 111 

atten et thla •tun "but% wU1. be S].a4, ot aoune, to 11• rq om 

attention to 11r. lrd.th'• J1l"OllOl8.l attar a tboroi.Jab ll'tWI¥ aid. an ap- JN1Ml or it i.. been -se 'b.J cnrr Wtl7 CQDPtent techDS.eal statt - aert.&tn otbeJ:' ~ 'llfll MllOC1ate•· 

l\Ult u 8Dorl u p:.aalble t vtll wite JOU ot the rel\U.ta ot ""*' ~ u4 ! bape both Ill-. lad.th u4 JGl V1U DOt be too 1m;etlent. 

h'ca JGlll" O'UX1 eqlrl.eDcft flt folwr &qa )'$1 c:eJ'ttt'D11 are Wll &llU'e 

flt the tact. tt.'tr ll'DPQll8.l.9 ~ thi• fM#t -.. to ua a a ~ •t.nam 

from pit.riotic citiaems u4 !nftntor• vbo t1D4 w.a fiel4 haclmti!Jg. Wwtumtel,y, 

~ 

'bllcauae t.1-7 4o llOt h&Te a.ccea• to th9 extaalve but 

oluaUl84 l.1terature that edm !n tht• n.14, 'tbe cblncea 

ot tllei.T ilmmtina ~ ~ ..,, u4 ue!'cl1 are n.tber -.u.. 

lllYertheleae, 'beeau.e tlwre ... elwp .,,. cbuce of tb18, ,. t.T7' to 

*1t at. each Jl'OJOl&l ta .. o'b.1eotiw a -=er u patble, tU14 thi• ....... t:Sm. 

tour letter liDSa both lfn, rr ..._n lt.ll4 ll'•l.t' tn aoo4 i.a.ith. 

% bi.w· J\lllt ftt\ll'Dl4. fl"Clla cmtr • Jalth • • •ence Sa SW:o~ Oil atticial 

""*lne•i1 to f!D! tlaat & ~lpt W W'OtAt OD lbllr.e•PMoN-laCOZl 

~JlihJ ,.. aw.r&:4 the $11000 l'oJcer Sbake•pea.n L1'tma:r7 li~ 

Jri.u• Ve boJ,19 to - it. pa,U.hed ftr¥ MOD· 

lince:re].t, 

a,_...ti_. - • I ..... -