'I 

-~~--,---- -------------- --~---- ---~- ---

/ -

'""'-. 

( ' REF :tp :_A414BB~ 

COPY 

' 

\ __ ; "- - ( \ 

____,. 

Subject Cipher Printing Telegraph Systems. 

BELL SYSTEM 

DEPJl..RTMBNT OF DF.VELOPtJ!&;fJ'I' & llliSE/\.RCH 

195 Broadway, 

I~ew York, October 26, 1925. 

Major General Charles McK. Saltzman, 

Chief Signal Officer of the Army, 

Washington, D.c. 

My dear General Saltzman: 

As you know, we undertook during the war to develop fast and aooure.te methods for enciphering and deciphering telegra.ph messages, mo.king 

use of' printing telegraph apparatus. Tne arrangements proposed turned out 

to have such merit, and were used by the Signal Corps in this country and 

preparations were made for rather extensivo use in France. 

It has seamed to me that tho work vthich was done in this connection 

and the results which were obtained would make a suitable paper for preaontution to the Americnn Insti tut.a of Eleatric.nl Bngineere, and with that iq. 

mind the ono attached hereto has been prepared0 with the thought that ii/ would 

be presented at tha nntional convention of the American-Institute of Electrical 

Engineers to be held in lJew Yorli.:: eo.rly in F0bruo.ryl) 

The paper, as you uill note, is, in the Tlll-.:in, of a descriptive char• 

act.er and deals alnost entirely with the features of tho particular system 

which has been worked out. 

Before going any further with the matter I should appreciate receiving 

your comments on the proposal to give such a paper nnd, if you see no objection to its presentation, to have the benefit or such detailed comments in re• 

gard to the text as you may be vrUling to make. Some time ago when Captain 

Friedman was here I spoke to him about the . matter, and gathered from what. he 

aa.id thut he thought such a papar would be timely nnd helpful. 

In connect.ion ·with this development we hutl some helpful corr.inents from 

. ;,'.?-a.me of tho Si{~nel Corps people, and I want to be sure that full credit is 

·: '.~~ven for their help; also for the recent improvements which ha<tfe be:Jn sugf:ested by Ca.pt.a.in Friedman since the system vms worked out. 

In the event the.t the. psper 1s presented it would be our plan, I think, 

to have somo equipment a.nd to make a domonstration, as I think such a demonstration would be very interesting to the membors of the Institute. 

@'pp roved for Release by NSA on 11-18-2014 pursuantto E _O _ 1352a 

- ---~-·--------~ 
REF ID:A414B1857 

Major General Saltzman -2-, 

As papers for the February convention should be in the hands 

of the ?Aeetinge and Pe.pars C.ommittee early in De,oember, I should be 

obliged to you if you vrould let m.0) he..ve your comments at a..'11 early 

date, and I trust you will bo entirely frank both as to the wisdom 

of preae!lting such a pa.per and ns to any comments concerning the 

material therein. · 

iiith kindest regards, I am, 

.Attached: 

Draft of' paper, 11Clpher 

Printing Telegraph Systems 

for Saoret Wire and Radio 

Tolegraphic Comrnunioations." 

RDP-m.m 

Very sincerely yours, 

L. F. Morehouse,. 

Equipment Development Engineer • 

_J 
• REF ID:A414.57 ........ 

Notes on A. T._& T Co's. Paper on 

C·ipher J:lrinting Telegraph Systems for Secret 

Wire and Radiotelegraphic Communications. 

~~ 

1. /'..bugges~that the designation "U.S. Signal Corps" 

' ., ,) 

be changed to "Signal Corps, U.S. Army." 

2. Several times in the paper the apparc.tus, system, 

and method are referred to as being "secret", and reference 

is made 

~ 

to sending messages secretly. To be 1'ee-brteall' 

accurate, it is not the apparatus,system, method, or actual " - transmission which is secret, since the latter are fully ~~~i:L 

described in the letters patent covering them, and~are therefore available to the public. The point is that the messages 

I 

) 

k ~duced by·--~~; sec~ One of the requirements .e 

of a cipher system suitable for use in the military service is~ 

that there b·e no secrecy 

~ 

about the method or a~atus. See 1 ~ ~t() . Wo.JJ~~~ l'ar. 75b, page 114,"Tr~ining Pamphlet No. 3")"v)..Q~t .. ·~, •-e.o·~ 

3. Page 11. To telegraph engineers who are familiar ev:> ~'). -\e ~~IN~~) 

with the rules regarding word count"QBa ?sie~but not with 

the principles of cryptography, the distinction between code 

and cipher, as stated, will appear to be unusual and perhaps 

faulty. The distinction as stated is strictly true in the 

technical cryptographic sense, and the distinction made in 

commercial practice had its origin in this cryptographic dif- -~ 

ference, but

1

,has become obscure in recent years. In commercial 

count, messages are regarded as being in code if the words 

are (1) real dictionary words taken from one of eight authorized languages or (2) artificial words that are pronounceable 
guages: cipher messages are those in which either groups of ~CA-~ • 

figures~or unpronounceable gro°tips of lett~mployed. ,~c.~~~> It is obvious that cipher systems can produce pronounceable ,... 

or genuine words only by accident, whereas code systems employing artificial~e can be designed to produce pronounce- ,,~,. 

able g-!'Oups regularly. It might be well to add that the present 

distinction employed in the telegraph and cable administrations 

has led to such great practical difficulties in the interpretation and application of the rules that a revision of the latter, 

toward clarification and simplification, forms the subject of 

much discussion at the International Telegraph Conference now 

in session at Paris. I might also add in passing that in my 

opinion cipher systems and apparatus will never supplant or 

even become real competitors of code systems in the commercial 

world until the present rules and rates for cablegrams are 

modified to reduce the advantag~which the code count now has 

'w. WilP!k'-"~ over the cipher count. 'This is because two code groups, if 

combined in one ten-letter " group that is "pronounceable"!. can 

W.o..~<>--.J c,..~.tr~ be sent and are charged for as one word~ Thus, a code ~~m, 

even one in which each plain text word is merely replaced by a 

five-letter code word, can be sent at half the cost of a cipher 

~4~ When one ,,~ considers the abbreviating or con-

._5@!a Mil!) ~condensing._ features of code, where a phrase of three 

or four words, or even a long sentence can b,e represented by a 

single code word of five letters, the handicap that cipher 

systems encounter is most strik~ng. Perhaps the use of rapid, 

efficient, and inexpensive cryptographic apparatus will reduce 

this handicap to a considerable extent")~- ~I "ta.o. ~ow-

~~~~Ur-~~ .t~~.~ 

~~~lo~~r~~- . 
• REF ID:A4141157 

"19" 

4. Page 20. The statement that the double-key system 

can be used "without appreciably reducing the secrecy of the 

system" ii&- considerably underestimat~ the degree of success 

that the expert cryptanalyst may have in attacking messages 

prepared in this way as compared with the case wherein a single 

non-repeating key is used. 

5. Page 24. May it not be worth while to include a mention 

of the services rendered by the Cipher Department of the Riverbank Laboratories, Geneva, Illinois, in connection with the 

':? tests to determine the degree of secrecy. These tests were~ 

~- ~ o....JLw~~~ot-~ ~·official"character and were made at the request"ef1li.~fte 

~s· ~~~~ ~~~ t~ ~~ 

tQ ~~.._ ~' ..J~~~~~~. I.ft_ ~- .~ G L~. 1· ,, tae_1 C;...1~ cl~~ ok-~ ~ .~ ~b l-.M 

~ 

·~~"CA( \ r ,. ~r ~-u ~ ~i ~ a~.:t!f WGVO ' IMkt.. c,... I~ u ..... \) b- -- ""' } G w. F. FRIEDMAN' - D Al<' Cryptanalyst, s·i"§'nsl 8tf.E;pe. - ,lo;, ..l ,0, 

\9,lAIZ'>-0 ~ .....,J'e""'- ~ 1Re_ ~ ~. ~ :1 

·~~~d~~.tt::::_~~ ~~~,-~, 7cJ~-(\ ~ - ~~. . 

~~~~i&-e .- ~~°!J 

~~~~~~~-

•