' 14 - ""'...... "l'•A... v- , ~ ': .NONREGJSTE~D ~-""- ..... ~ - ,,. ,.. .J ~\ ' - "":..- .;- \ . - . 'P? .... _ \ ( r ( T' ... - -~ 1 .. -, CONF'IDEN1 IAL ...,. ' ... ""' -- ft .:: JI, ........ ~ ... ,. .... ' .. - ~'" ~ --~:.:~~ Security ..lnformation-- ...!' • - .z ... :-... - I, , - .. - -. .... ; • < ~ -.L .,..,J?l- ~ ,, C..!-- ,... ... "'~~""i .. "" ~ ..... ~ "'~.i- - "e ... ~, J .i. .... .,.....,, ~ - -.. '"u ::- .- .., ... .. ... ' FUNDAMENTALS OF ·- TRANSMISSION SECURITY-cJOINT. This aoC".. ment c::insasts of cover and 6o numbered pa;es 1 1o 66 1nc:lus1ve V•1fy presence of eaclt page upon receipt - ... ,- DEPARTMENT OF DEFENSE ARMED FORCES SECURITY AGENCY t -t- I .. .r ,_ .... "''/- ~ • WASHINGT01(25, Q C. -r·-- , . ' . .......... ,_ ~ ------- • 2 AFSAG~248 REF ID..:A5?B • NONR EGISTERED CONFIDENTIAL Security Information FUNDAMENTALS OF TRANSMISSION SECURITY-JOINT This document consists of cover and 66 numbered pages 1 to 66 1nclus1ve Verify presence of each page upon receipt DEPARTMENT OF DEFENSE ARMED FORCES SECURITY AGENCY WASHINGTON 25, D C SEPTEMBER 1952 CONFIDENTIAL - 1- ORIGINAL REF ID:A57822 AFSAG 1248 CONPIBl!l!f'fl1d:i DEPARTMENT OF DEFENSE ARMED FORCES SECURITY AGENCY WASHINGTON 25, DC 1 September 1952 FUNDAMENTALS OF TRANSMISSION SECURITY - JOINT LETTER OF PROMULGATION 1 AFSAG 1248 is a CONFIDENTIAL, Nonregistered Pubhcabon and will be handled, stored and accounted for in accordance with current regulations of each Service 2 AFSAG 1248 will become effective upon receipt Instructions for the eventual disposal of AFSAG 1248 will be issued at an appropriate time by the Director, Armed Forces Security Agency, through normal Service channels 3 Changes to this pubhcation will be promulgated by means of a letter, memorandum or message and are to be entered upon receipt The individual entering the change shall so indicate on the Record of Corrections page included herein as page 3 4. This pubhcabon is issued to those units designated by the Director, Armed Forces Security Agency, the Chief, Army Security Agency, the Director, Naval Communications, and the Command­ ing General, U s Air Force Security service 5 THIS DOCUMENT CONTAINS INFORMATION AFFECTING THE NATIONAL DEFENSE OF THE UNITED STATES WITHIN THE MEANING OF THE ESPIONAGE LAWS, TITLE 18, U S C , SEC­ TIONS 793, 794 AND TITLE 5ff, U S C , SECTIONS 46, 46a AND 46b ITS TRANSMISSION OR THE REVELATION OF ITS CONTENTS IN ANY MANNER TO AN UNAUTHORIZED PERSON IS PROHIBI­ TED BY LAW 6 EXTRACTS FROM THIS DOCUMENT MAY BE MADE IF NECESSARY SUCH EXTRACTS WILL BE SAFEGUARDED IN ACCORDANCE WITH CURRENT SERVICE REGULATIONS 7 This publication will not be carried m aircraft for use therein RALPH J CANINE MaJor General, US Army Director, Armed Forces Security Agency - 2 - ORIGINAL REF ID:A5782- AFSAG 1:148 RECORD OF CORRECTIONS Identification of By whom entered Correction or Change Date Entered (Signature, rank or rate and Heir No {if anv) Name of Command) ORIGINAL - 3 - Reverse (Page 4) Blank REF ID:A5782~ AFSAG 1248 TABLE OF CONTENTS CHAPTER 1 GENERAL Section Paragraph Page llflflf - INTRODUCTION Purpose 1,.,,.,1 9 Application 1,.,,.,2 9 Comments 1,.,,.,3 9 lllflf - DEFINITIONS AND RESPONSIBILITIES Transmission Security 11,.,l 1,., Joint Application of Transmission Security Measures 11112 1,., Responsibility for Transmission Security 11,.,3 IS, 11 126,., - MILITARY NECESSITY FOR TRANSMISSION SECURITY General 12,.,l 12 Intelligence Available Through Traffic Analysis 12,.,2 12, 13 13,.,jf - MEANS OF PROVIDING TRANSMISSION SECURITY General 13Sl 14 Training 13112 14, 15 Monitoring 13,.,3 15, 16 Remedial Action 13,.,4 16 CHAPTER 2 TRANSMISSION SECURITY IN COMMUNICATION PLANNING 2,.,,.,,., - INTRODUCTION General Communication Planning 2,.,,.,1 17 Local Communication Planning 2,.,,.,2 17 21,.,S - GENERAL REQUIREMENTS Call Signs, Routing Indicators, and Address Designations 21,.,l 18, 19 Serial Numbers 21,.,2 19 Cryptographic Systems 21,.,3 19, 211 Authentication Systems 21,.,4 2,., Reserve Operating Instructions 21,.,5 2,., Test Transmissions 21116 2,., Communication Silence 21,.,7 2,., Transmission of Classified Information 21,.,8 2,., 22,.,,., - RADIO TRANSMISSION SECURITY Nature of Radio Transmissions 22111 21 Interference with Radio Transmissions 22,.,2 21 Range of Radio Transmissions 22,.,3 21 Assignment of Frequencies 22,.,4 21 Equipment 22,.,5 22 Approval of Radio Circuits 22116 22 2311,., -WIRE TRANSMISSION SECURITY Nature of Wire Transmissions 23111 23 Approved Wire Circuits 231§2 23, 24, 25 - 5 - ORIGINAL REF ID:A57822 eON'f'IBElH'i"E/zJ:a AFSAG 1248 Section Paragraph Page 24fJll - VISUAL TRANSMISSION SECURITY Nature of Visual Transnussions 2401 26 Uses 24fJ2 26 Approval of Visual Circuits 2403 26 25fJ0 - SECURITY OF OTHER MEANS OF TRANSMISSION Nature of Other Means of Transmission 25f}l 27 Non-Electrical Sound Systems 25fJ2' 27 Electrical Sound Systems 2503 27 2600 - SPECIAL SECURITY MEASURES Purpose and Authority 2601 28 Planning 2602 28 Implementation 2603 28 CHAPTER 3 TRANSMISSION SECURITY IN MESSAGE DRAFTING 3lffJlf - GENERAL Effect of Message Drafting on Transmission Security 29 The Message Originator 29 3lfJfJ - ORIGINATOR'S RESPONSIBILITY FOR TRANSMISSION SECURITY Mlrumum Transmission of Messages 3101 30 Brevity 31fJ2 30 Clarity 31fJ3 30 Security Classification 3104 30 Precedence 3105 30 Addressees 3106 31 Cancellations 3107 31 Classified Information in Plain Language 31fl8 31 CHAPTER 4 TRANSMISSION SECURITY IN COMMUNICATION OPERATIONS 4lflflf - GENERAL Circuit Discipline 4fJfJ1 33 Mlmmum Transmission by Electrical Means 4flll2 33 Transnussion of Classified Information in Plain Language 4flfj3 33, 34 Call Signs, Routing Indicators, and Addressing Information 4f}fl4 34, 35, 36 Defense Against Imitative Deception 4flfl5 36, 37 41lllf - SECURITY OF RADIO TRANSMISSION General 4llfl 38, 39, 4ll Radiotelegraph 41fJ2 41 Radiotelephone 4UJ3 41 Radioteletype 41fl4 41 42fJfJ - SECURITY OF WIRE TRANSMISSION General 42lf 1 42 Telephone 42lf 2 42 43lflf - SECURITY OF VISUAL TRANSMISSION General 43lf 1 43 Visual Methods 43fl2 43 Visual Silence 43fJ3 44 Monitoring of Visual Circuits 43f}4 44 - 6 - ORIGINAL REF ID:A5782. AFSAG 1248 Section Paragraph Page 441:'ll:'f - REPORTING TRANSMISSION SECURITY VIOLATIONS General 441:'ll 45 Possible Disclosures of Classified Information 441:'l2 45, 46 Procedural Malpractices 441:'l3 46 CHAPTER 5 SECURITY MONITORING AND ANALYSIS 51:'fl:'ffl - GENERAL Introduction 51:'ll.U 47 Defimtion 501:'l2 47 Function of Command 51:'l03 47 Function of Evaluating Agencies 51:'ll:'l4 47, 48 5ll:'ll:'l - OBTAINING TRAFFIC General 511:'ll 49 Method 511:'l2 49 Monitoring Equipment 5103 49 Recording Equipment 511:'l4 49, 51:'l 521:'f0 - METHODS AND TECHNIQUES OF ANALYSIS General 521:'ll 51 Processing 521:'l2 51 Derivation of In.formation 5203 51 Reconstruction of the Communication Organization 521:'f 4 51, 52 Procedure Analysis 521:'l5 52 Statistical Studies 521:'l6 52, 53 531:'ll:'f - REPORTING TRANSMISSION SECURITY VIOLATIONS General 531:'ll 54 Procedure Discrepancy Reports(Communicabon Improvement Memoranda) 531:'f 2 54 541:'fl:'f - APPLICATIONS Command 541:'ll 55 Technical 541:'l2 55 ORIGINAL - 7 - Reverse (Page 8) Blank REF ID:A5782- AFSAG 1248 CHAPTER 1 GENERAL ll:Jl:Jj,J - INTRODUCTION UJl:Jl PURPOSE - Fundamentals of Transmission Security - Joint, AFSAG 1248, has been pre­ pared to formallze and promulgate those principles of transmission security necessary for commu­ nication planning and operation ll:llf 2 APPLICATION a The effectiveness of transmission security measures is dependent upon coordinated and consistent application of security principles in all phases of communications Those responsible for transmission security (commanders) and those through whom the responsibility for transmission security is fulfilled (communication and signal officers) must be cognizant of any aspect of commu mcations which affects transmission security, whether it is commumcation planning, message drafting, communication operations, or security momtoring AFSAG 1248 provides the basis for such coordinated and consistent apphcatlon of transmission security principles b AFSAG 1248 provides a standard reference for those engaged in preparation and im­ plementation of commurucation plans and operating procedures Principles set forth herein are incorporated in Communication Instructions (JANAP/ ACP) as appropriate, but the contents of this manual are not to be construed to prohibit changes in Commumcation Instructions to those pro­ cedures which are of a purely operational nature AFSAG 1248 also provides a guide for use in training personnel in the provision and maintenance of transmission security 11:ll:l3 COMMENTS - Comments regarding any portion of AFSAG 1248 are invited and should be submitted to the Director, Armed Forces Security Agency, Washington 25, D C , through Service channels 0 0HPIBBH'f'tAl:i - 9 - ORIGINAL REF ID:A57822 00HFIBEKTmL AFSAG 1248 11"" - DEFINITIONS AND RESPONSIBILITIES 11"1 TRANSMISSION SECURITY - Transmission security ls that component of communication security which results from all measures designed to protect transmissions from unauthorized interception, traffic analysis, and imitative deception a Interception - Interception ls the process of obtaining communications intended for others All communications are subJect to interception in transmission, but some means of trans­ mission are inherently more secure against interception than others Interception has as its ulti­ mate purpose the derivation of intelligence b Traffic Analysis