Personc.l Files ~·:. F. ?riedn:an 

b.'} 311.5 (4-14-30) 

Pub. 

Subject:: Codes, ciphers, secre.t inks, rc-d.io int.erct::ption .,,nd 

g~niomet.ry. 

To: The Chief $ignal Officer 

1. Reference resno1.sioilities of C.S. O. in c..ccord with AR 105-5 .&.no 

chan~e ~:o •. 1 thereto of ~=~y 10~ 1927. Followin~ stc.te..11ent of · .. c.r Dept. 

policies trans1itted. 

311 · .!;-

2 .a. i..Jt. 105-5 as &Ir.ended pl.Lees resronsibilitJ' ~or fol:J_owin~ o.ctivities 

on Chie!' Si:-nal C'fficer. 

(1) Code &nd Cipher Corr,pilc.tjon 

(2) Code <:tnd ""i;hsr ~elution 

(3) Intercedion of emeay rc:.dio r..nd ,.ire tra. :'!'ic 

(L.) Location o!: ener.,7 rc..dio trensudt'tino: su t.ions o;v .:;or.ioi:."'tric 

.r.eans. 

(5) L.e.boro.tor:; ~r?'<:r·->;":.!1.ent.s for err.plo;\·.:1ent iind detection o.!' secret 

inks. 

b. 11The fundc..-r.entc.l rec..sor. for Fl .. cin:: the !'esrionsibility :or t.hc.se 

duties upon T.!1e C:hief Sigr..r-1 i''fficer is thc."L es.11 co:::-relatt.d duLies in connE.ction ,·ith secret co:'". unicc.t.ion n.c..y oe "'ssigned to .:me 01.crc..t.ins &.~cnc~r 

for efficiency of oper~tion. 'Io serve tr.is urpose t.l".1:::se duties wil_ ·:Je 

or~anized by the Ct:.ie:f Si91c-l '.:if!'icer inT.o " sincle ccc.rdin:..ted se:-vice. :r 

c. ;..t discretion o" :;i..jpf' :!..gna Cfficer 11 it. is su:;!5est.ed th.:.t. 1 .Signal Intel~igence Servic~' be the desi~ndtion for thi~ coor:inc..t.ed service'. 

3. '

1 .Lhe general rr.ission uf this service is, c..s for c:.1.:::..:i. othar rr.:.J.ii:.Clry s~rvices, the proper organization ~nd develo1ment in ~e•cet.;..rr.e Lo the and 

tt.:..t the service m~y oe >:.repc:.red to operc..te ~t i .... ximwn efficier.cy in wc:1.r •. , 

4. The specific missions 

a. fhe prepc..ra.tion and rev.Ls:...on of a.11 coces ciphers .a.na other raeans 

of secret communic&tion to be err.ployed by .... rmy in tin1e of Feil.ce c..nd w ... r (note: 

current J..R m&ke tr.is o!'fice responsible for the printing of codes ... nd 

ciphers, for their d.istribution in accordance with distribution tables prepared b1 the CSO Ernd for their accounting~ 

b. 11 In ti.roe of war the ;_nterception ener..y comnunications by electricu 

means", location or ene..rny r&.dio trG.nsmittin~ stations by goniometric means; 

";md in peace tiJ11J! the necessary or~· · ~ a.nd trc.ining of personnel end 

the necessary development of enuipm er this service ca.pc.ble of ~ 

immediate operation in wa.r. 11 (J 

Declassified and approved for release by NSA on 07-29-2014 pursuant to E.O. 1352B "1..-
c. 11 In time of w:Jr th,, sol • _ Be!J:6(§fi>r c"is-uised enerri;· rr.ess:..ges 

or other docuraer '', intercepted by A:rmy, or for tded b~r other o.:;encies 

for solution. In peace resea..rch work, uzrn;~ and ore;;anization c..nd tri:.ininf; 

of ,personnel to render this service ca m.ble of imr:-edia.te oper•tior:. in wc-r. 

d. laboratory arr~mgcme.nt.s for detection of intercepted enemy docurr.ents written in secret ink, and for selection c.nd .:reparc:.tio of secret 

inks "to be eir.ployed by authorized a;;;;tmts of our own forces in time of 

wa.r; and in pec..ce time necess;,,ry rese·-rch war}:: to render this service 

capable of im.!Ti.ediate oper&tion in ~~r.~ 

5. ?'obil!.zation :!'lans 

c:... Under • -~.r Dept. 

(1) Prep;,.r&tion of a.11 r..ec.ns of secret co:r.rr.unicr.t:;..on eP."!ployed o;r 

J...rrr.y in peace o.nd v.~.r including secret. inks, excest thc.t u::ion 

it& or£<.:.r.ization ~E~ will oe5in prep~rc.tion of field codes c:..nd 

ciphers rec. uired for current repl2.ce1:.ent for suboraim ... t.e ·.mi t.s. 

(2) Interce1,tion . f ene.::.y cor..munic.r.tions &."ld ~oniorr.e::tric erk 

incicent to it. 

l3) Detection unc solution of secret inks. 

(1) R.e-;:ilc..ce:_ent ~ield codes e:nd ci:phers 

(2) Interception 

(3) tonio~etric locet~on 

(4) Solution of cor.::..-:mnic<.tions in code, ci:Jher, secret ink or 

other dis !:;Uise • 

c. B~. Field nr~ies 

( 1 • -J 

( 3) 

Int.erce~tion (2) ~onionet.ric locc.tion 

11 i'he solution of ir:.tercepted ene.::i;-7 code or cipher r.essc- :es o:r the 

e:ssist; nee of ci':'"':ir keys c:.nd solved codes ::.: s furnished o-.- th~ 

service c. t '1enertl Hea.d~UG.rters. 11 

6. Bc.sed on t.l:ese policies, CSC to 11 sub:r,it dt c conveniently e.:..:-1,: ci:t.e 

a r<=.coirr.ended dr..J ft for c.n i-..rm;; ~ef:ulc:.tion to cover the functions c..nc.! c :n. ics 

of this service. 11 X trc;.w uri ~daition~l regulG..t.ions c;.de'"mite to cover 

activities of se ·vice and deemed c... ;"'ropri&te for :.iublic..,,,t.i.on. 

7. ?eace Time objectives. 

Ji. Code Compilation 

(1) Ultima~e aim !the ?reparation of Authorized codes, satisf~ctory 

in char&cter .ind sufficient in the n~nber of copies end editions, for enployment by the ,,rm;y during both ,:-•eace a.nd. wear". 

SEBRET ............................................ ___ , ____________________________________________ ~~~~~~~~~~--------
REFS6Cit+666 

then war comes for secrecy reasons necess ... ry 11 to che1n3e cert1:1.in 

characti.::ristics of the codes er=iployed durin~ oeace, and the r-r!uired 

number of copies of ea.ch code will be ,,,;reatly increased". Prep.:.:rc-:.tion 

&nd publication of codes reNdred considerc..ble t.ime•, 11 it would be 

improvident to wo.i t till the outbre~k of v.u.r to oegin this work" 

(2) As objective in peace, .as funcs c.vd.ilable "there will be at 

all times in the possession of the office a.1'iJ for immediate distrioution 

one edition cf e~ch authorized secret code, with cipher t~~lcs if 

necessary, o.nd in the posse.sion of the C>:ief Si~2l Officer "LWO 

reserve editions of such codes and. cipher t.:..bles. 11 

b. Code i..nd cipher selution. 

(1) Ultirr..c..te aim in ~-eace is "Lrc.inin?, of sufficient personnel 

to develoti exμerts in so:i..ution of enerr.:r code c..nd ciohc..r ::.essc..ges in 

war. ',{ill re"'uire rr.uch tiir.e. Lo.r.:f.e cmr.r..ancs re,..·uire oper ... tion of 

tr.is activity in ~ea.cer.ime training. "it is r1ecessary the:.t it o::ii::r. te 

for therr. durin.: t:t.eir training exerc::.ses 11 , ,'oint .n.rr1i:v &.ne .~c..vy F...c.neuv":!:-s etc. 

Objective·s should oe in .-ec..ce 

(1) Traini~~ ·ersonnel 

(2) Furnishinf specialists to l ... r.:;e cor . .r.,o..nC:s for ~,e .... ce 

time r aneuvers c..ftt:;r :- ersonnt::l r.a.s oeen sufficit::nt2.y 

trai!'led. 

Pe~ce tir".i.e tr&inin~ to ue centrc.lized under OCSigO. Co~p~r~tlvely 

small nurr.ber of t.rc..ined nersonnel t.o be &.ssi,;ned to cor::os .&.re::rs &.na C:e~ts. 

for inc-.neuvers c..nc returned. to OCSif;·:. 'f is will insure necesse1ry 

continuity of initic...l tre::.inin-: undt:ir JCSi~-, only ruilit.ai.r:r a·.- _nc:• 

present:...:r c::ua~i!'~ed t.o ca¥ r~· it or.. }!;c.ch corps o.re;: or der urt· cnt 

re"uiring service should ultinlC. tel~; tt,, in a :;osit.'..on t.o ~·urnish ir.-

de~endently. There~ore CSO should be pre:;J...red to furnish trained 

specie.lists of this service !'or r1er· ... nent as.::>ii:n.i11er.t to such c:::>rps <:.rec..s 

or aeni-s. o.s · 1) :r.<:.y lc.ter decide, v.he::n trainin:; has .~repc:red su:'ficit:mt 

oersonnel able to functi0n &s inde~endent unit. 

C. Radio Interce~t 

(1) Close rel~tion to code .... nd ci;her solution, since inr.erce:tion 

airriess unless mess•ee~ solved on other h~nd solut:on dependent on 

intercer t for mater ii( '

1It is evident, ther~i'0re t11.. t the oper·c-.t~on of 

both se1 .. vices should be ca.rried on in close .Li.s.ison. 11 Ultimate t.r::.ining of both involves mutually coordinated opi:.rc.tion. 

(2) Pe~ce time proble~s 

1st Develoμnent of e~uiJ:rnent 

2r.d Develop.'1.i.ent 

need for this service in 

o! technir•ue of cperdting J;er::.onne=l 

maSEVCRET 
It is also a possibility that duriflb peace time or during perioC.s 

of str&ined relations the ~·:ar Department or COJI1.manders of Depe1rtments ~nd of certa.in corps areas ~•Y desire the operc.tion o!" t~is 

service, provided the services of & code and cipher solution asency 

Cbll be made &vailable 11 • 

PrQci.ical operation is region~l and "cannot be concentrated in a.ny 

locei.lity11 as code and cipher solutlon can. 11 In other words intercert 

sti..tions r..u,st be locc;.ted «t c·~rtain criticcl points where their operation .. .ay be effective", in dept.s. 01nd corps ~rea.s, while solution ma? 

be a.nyt·.here, provided :;>roper communica.tions facilitit..s between the 

two &re available. 

(3) Peace objectives 

(a) Developr..ent of esuipment uncier CSO 

(b) Loc&tion of int.~rcep~ stdtion to oe ;.rep.;..red to oper~te 

directly under CSO 

(c) ~'!hen su!!"icient eruip;;.1ent developed loca.tion of stc."Lions -11. 

crit,ical points 

(1) Ha.4iian Dept. 

(2) Pet.n&llb. Canal Dept. 

(J) Phili pine Dept.. 

(4) ~iehth Corps Area 

(5) t:inth CorFs Area 

•ro pperc.te under dept. a.nd corps are;•. cor.-a.-nders CSC to 

reconmend when such stliltions should be estc.blished ar.d then 

·:a .. will take up with de~. &nd. corps arelii. com::.a.nders ccnce1~ned. 

(4) Plans for interception 

(a) ·.,hen certain interceJ•tiuns desired by ;ID, CSO will recommend sta. ti on or stations best e:.ble to perf ori:. service. ·;,1) 

will issue necessary instruct~ons. 

( b) C:orr.s arec. or dept. corr.rr.<i.nder desiring !interceptions will 

obt&in them b•· facilities under t.hair control. 

(c) ~essages intercepted by CSO stations will be tr•n mittea to 

his solution service 

(d) Cor~s are; or eept intercepts transmitted by mail to ·n 

for solution by CSC solution service until solution estcblished 

in corps •rea or dept. 

SEBHET 
... • 

l. Goniometry 

Results in two ..oh~ses rerformed by same units one supplement~l to 

radio intE1rception one E;ivins locc-tion o!' enemy rd.die transrr.ittinc 

st•tions end indic&ting tactical disposition of enemy. 

Plans for peace to include development of er-uipr.1en1..., or:,· niz~tion 

and trkinins of personnel, and location of stutions for £Dniome~c 

service si.It.ilar to intercept plans. 

L. Secret Inks. objectives 

In pe•ce: estcblish small l.i..boratory for reae&rch to ~reduce 

In wa.r: esto;,blish a.eency :'or the detcct ·.on of secret inks er .. -

ployed by lhe eneJ'l\Y - reconc.endation of suitable secret in~:s for '' se 

by our authorlzed a.:;ents. 

By order of the Decretc:.ry o!' · :~r 

Alfred J. 3ooth 

Adjutant 1eneral