Description of document: National Security Agency (NSA) document: A History of U.S. Communications Security Post World-War II – released under Mandatory Declassification Review (MDR) Released date: February 2011 Posted date: 07-November-2011 Source of document: National Security Agency Declassification Services (DJ5) Suite 6884, Bldg. SAB2 9800 Savage Road Ft. George G. Meade, MD, 20755-6884 Note: Although the titles are similar, this document should not be confused with the David G. Boak Lectures available: http://www.governmentattic.org/2docs/Hist_US_COMSEC_Boak_NSA_1973.pdf The governmentattic.org web site (“the site”) is noncommercial and free to the public. The site and materials made available on the site, such as this file, are for reference only. The governmentattic.org web site and its principals have made every effort to make this information as complete and as accurate as possible, however, there may be mistakes and omissions, both typographical and in content. 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Army, the U.S. Navy, and the U.S. Air Force on 02-04-2011 b_ursuantto E.O. 13526. MDR 59142 SfER:E'f corv11fff) SEeftET ,\dmowl<ulgenwnl~ The ;.;ourtr!s used in compilin~ this history arc many and ,·aricd. We an~ f!SJJecially undclitcd to l-lr. Gf~lrgc II owe, r-.;sA II istoriun from 19 to 19 , f11r I he significant contrihuti(ms he htts made to t.he l\gcncy's heritage in his lh·e vdume draft of The. Narrative /lis tory of AFSA . .VS:\ ~ The portion of I he II istor·y covering most :1Hpccts of wirt!d rotor dcvclopnumt is hasf!O on A Sun·ey of Wired /lotors whi<~h was prci#'~d hy a long time expert in that fiP-Id, :\tr. Ryun Page ::\.lr. Po1gc's survey is pr·cscntly being rcvicwt.>d and updul.cd, and will he published in due cour!-'c ns an acljuncllo this llistory ofCommuni<:at.ions &.-eurity. Additionally, an cxt!lnsiv<J work h. years to , has h(!CO used as a sprinnbmtrd for tiw Iimitml entries hen• in on S<!curc vnice rnattcn;. This work will be published at some ful.urc date also. P.L. 86-36 . ·· Alhil'd and mostJmporlant hisloril:al study in trucking the development of critical This work rcvinws the major technical and managnrial problems which were cncounlcn.>d in the 14- dc,·clopmcnL of a widcband voice security system for tactical airborn<!, ,-chicular, and manpa9f applications. This prognnn covcn.'<l about twenty years and resulted in the highly acclaimed y"i TSEC/KY-8, I·'Y -28, and K Y-:i8 syshmts. 'l'his historical study will also be publh:hed in due coursn as a further adjunct to this II is tory . .:\lany thanks go, also, to the numerous pa:;t and J>rc,;cnt employees of the S Or·ganizalion for their valuable ad\·ice and assistance. SECRET SECRET l•"oreword In his trcati;.:e entitled "The Fir·st SIGI:\T Organization,"! :\Jr. Htli :.hlh,nrd. u lt•rm<!r ••wmlwr 11f thl! Dir·ccl.orale or GCilq,:z dr• ... :rtbmlthc.> M!CIIt! inllrnry V • ..\r·lll. Scene II, whi<:h showed Shakespl'<li'C's awareness oflhc po;.:sihi!itim~ ofSIGI:'\'1'. In that scene, a conspiracy led by th(! Earl of Cambridge is unmasked when a Lord, in an aside, nhscrves that "the King hath nol.e of' all that they intend, by interception which they dream not of." 'I' he King addresses the conspirators, and hands each om! a slip of paper purporting to be a commission. Each, upon reading his paper·, turns puh! and falls to his knees, pleading forgiveness. According to 1\lr. :Millward, the slips of paper were quite likely hits '/ ofSlGI.:'\'1' end-product bused on the King's int~rccplions. '!'hi~; story is import-ant he<:am;c it dramati;.ws what may he the lirsl known, dtx:unHmlcd, uncc1uivocally re~ogni.,;ahlc ahscnce of prudnnt communkalions security practices. I I ad the conspirutors the good sense to apply CO:\ISEC principles t.o l.h{~ir t~onspiritorial noh!S, writs, Idlers, nnd other communications, and th<Jrchy prevented the King from learning of their plots, thct·c is no way of knowing what. ciTcct their dastardly actions might have had on fl('nry V's reign nor on Shakespeare's telling of it. For all of that, it. was still many years before lhc art of communications security reached the point of being a much used and accepted looJ. I Contact., 19 . 2~tr. W. :\-t iII ward, C. B., C.B.E. was formerly Di r<.'Clor of l~cquirements at GCI f(.l SECRET ·: .... SECRET Introduction The history of the i.nvention, development, and appl'ication of cryptographic devices, machines, and associated apparatas and material is long and int-eFesting. Attempts to keep secure , · o·-y~n,:t-afto1? the contents of the various communications passing between and among Civil and military~- ~ . hav.e gone through many vissicitudes over the yeaz:s, not always with a great deal of saccess. This is .. ~-·· . r.<.':"' P .. ··- .; evideneed•from the·~fiest days in the ebservations ef Sir F-rancis Bacon who, in 1623, noted that " ... many times the greatest matters are committed to fatur-e and weak ciphers. "1 Until the advent of electr.anic/eipher machines, most cryptagraphic devices were built upon or around concentric circular rotating aumaers such as cipher wheels, cipher d~cs, e~. One of the earliest developments of such deVices appeared in Italy areund 1476 in a paper written by an Italian cryptologist named Alberti. There we;e a few mod-ifications made from time to time, but the basic methods of trying to keep -··---- --- - - ----·---- ·- .. ---------------·-···· - --- -- --··-·--------.. ~---·- -·----- lin Gifu_er.t-W.atts~tr:~l.!.~!atiohs (1640,. p;270~ of Bacon's Oe Augmeats Scierttarium, Landen, ____ / .~/ --···--··-····--·-········ ....... ··-····-·······-----·· ·····- -. .............. ~----·~···· -··· ·- ··-· -· ·····•· ... - ...... / ~$e £rom tim.e to time, h\il. tbe ba-sie methods of"tqing to ID>eep the underlying plain text I i communications "~ecure" remained. I I Progress in the development of cryptographic equipments and devices kept pace,. and I apparatus for protecting all manner of commuaications WeFe develaped and coatinaaUy perfected. ! These included machiJ:les aad keying device$ to secure Iiteral communications .whlch employed letters of the alphabet; ciiax transmi.ssians--which were picture oF facsimile traasmissions; a-ad · · t 1 h · "'" .. · · · · · · \ ctPhone~.inlr-8":2trr ansmtssxons-- e ep OQlc w.a-nsmissums. · I Early twentieth century communications ·se¢urity devices, such as those used 1,:1p to the t i 1930's, had been based prima-rily an tna,nual techniq.aes. This iacluded code .books, traasposition ! r I I processes, auxilliary devices for use with printed tables and books, strip-ciphers, and similar pr-ocesses ! I for disguising plain text messages. Additive tape machines had been used to a lim·ited degree. A few I j mechanical (i.e., non-electrical) ciphers such as the GeFman Ktyha aad the Hage.Ua devices had I 1 appear.ed h·ut had bee·n e·mployed a-nly ve:ry selec•tively or nc;>t at a,H b-y the U.S.. i \.--........,...i <::"'··· 1 SEC'R.ET §ECRET Eaciphering and deciphering were teQious, time consliming processes. The wired rotor, which became practicable for secure maclii:nes in the late '30s, was to revolutionize the encryption/decryption processes ofthe era. By early 1942 rotor machines were b@nnittg ta ease the l~ad on manlial sy.stems and to lower the time between filing of a message and delivery to its· inteaded recipient. At least this was . • ~ <• ••• ""~· · true·for;'majoi"rniHtary· bases·~··--As·World Wa,r·n prl)gressed; rotor n'iaehines··became flifr backbbn€fof·"" ·r.,, .·. · ''".'"··"· ··· the cipher networks at flXed plant levels for Army and Navy alike. (The Ak Foree had no~ yet been established a1:1 a separate service.) The use of rotors continued to grow through the 1941fs and early 1'50's. About that time techn·iques to supplant rotor;; became practicable and affordable. Miniature tubes came f:trSt, followed elosely by magnetic hinar.ies (BI-MAGS) and tra·nsistors_. Development of these, and of the later min-iat~rized technol&gj.es, spelled the eventaalend foF rotars in U.S. Cryptography. -Eeg/rt Even in the light of rapidly advancing technology, keeping our communications secure continues to be a difficult and challengiAg task. We have heeB emiBently successfwl so far, and our EO 1.4. (c) goal is to maintain that status. · P • L. 8 6-3 6 There are a number of reasons why this task ·graws even. more difficu•lt ..For qne, the SOviet Union has a very efficien·t SIGINT service which we must consider to he as dedicated ai.,.d determmed as our own. 'Phey target commun-ications world wide.\ \ \ J Another reason is that our exposure of communications signals increases re~Iarry.