I SECREI llJtDVOOII allk a l lfl lliV rBUl llilrBO IB WUtillilU WUllif mll 2nd Issue 1987 INODIN COICNORICATIONS 0 • Prederick aodean • •9 I NM' IIELEMAILE'fe E8tffMEMH · liCR r Declassified and Approved for Release by NSA on 10-21-2020 pursuant to E O 13526 MDR #107705 EO 3 3b 3 PL 86-36 50 USC 3605 • tl OEr 1 Ca t 1t 1U IC AT a s U irederlck -· _ - - - • ·- i _·· roilean g86 i• iff te 008 Telecommunicationa are in tranaition •• __ --- - - · ear y 19 modem communicationa bad become An early manifestation hu been t he ue or •• commonplace The moat n used for modem devieea that enable eommunice tora to intetpational communicatiem wu a V 26 device continue to em ploy existing aoaloe transmiiaion whiah operatea at 2400 bitsJ per eeeond today ayatems for puling intonnation that la the moet common ie the v t9 operating at digital form Thia ranaition ia already laaving biWaecond and alrudy devicea opera-ting an ef ect on the SIOINT communi • a lity to a data rat ea of 19 2 kilobltataecond in a voiceWe are pacle channel are being marketed Fig 1 iatlnr adiOU to cope with tliii muat also • look ahead to the digital communications • EQ QGQ Technical plaiaticalion of ayatems that are bound to be seen in the •mocum deuict• The unending que t to obtain tun higher data uanamillion coupled with the • nftd to maintain eatiaf'aewry bit error rat ea bu THE IMPACI' ON COLLECl'ION lead to the development of eztremely complex signaling devices Among that operate in at and a rd 4k Hs voice-grade hannel ia the now common axteen-atate Quadrature Amplitude Modulation 18QAM newer devices also employ complu codin schemes e g Trelll coding to achieve ma zimu4i data rates with aatiaf'aetory bit error rates I from ualor wavelorma to digi al ones- and-meros 9880 I ut II ratea -----------------1 • ED SG HigMr traMmiaion rata The baaic conceptual deal1D for moat of today • and Jaiae 1981 • CRYPTOLOG • pap t 81 8RIR' IIMISY 'M QQM lll' 8W91i1Y 9tR r fO 801PPMIQII' R9RRII' PCM • pul ocfed modula1ion 1 000 000 4th lev l PCM 100 000 10 000 Intermediate Data Rate Carriers 1 000 DATA RATES lrffobitslsec LOG SCALE 100 EO 3 3b 3 • • • • • • • • • • 1st level PCM ••••••••••• JO PL 86-36 50 USC 3605 I V 29 • 240A multi-tone telegraphy 1 1 9 7 5 I 1 • 5 0 1 9 9 0 ' 9 IJ s 2 0 0 0- Fig f DATA RATES COMMONLY• 0 SEO IN INTERNATIONAL COMMUNICATIONS • TD IMP A er ON PROCESSING 8 SGQ f ------ ' ' ---- • Although modem communications d o carry this same type of trafli they alllO aft used t o pe u other types communications sucho as computer--tocomputer file· transf'en iost-cornputer-to- or 2nd INue 1981 • CRYPTOLOO • pap 10· 81ff Ntl 9 Ha NDLil J lih G911DR' Q Riliii QNl lf ne eetPRW e'I' I BH8Rli1' terminal communicationa electronic mail etc To further compound the problem packetswitching la rapiclly replacing circuit swit ching u the preferred mean for digital comm wiications In a packet-switched communications network the me11agea are broken blto dilCl 8te data packets according to IODle rigid protocol Each packet contain addresaing and other c ommwrlcationa overhead information and ia handled u an independent entity thoupout the tranamisaion path When packeta reach their destination they are reaaaem blecl with other packets to reconstruct the orginal communication are many different protocols which must be addreaaed by any modem proceulng ayatem • 'f0 808 Handli 6 Mtcrogera« u data trcama Traditional teletype traffic atreama have homogeneous traflic types and employ homogeneous tnnmniuion codes while data ab'uma carried by modem lipala an often hevopneoua An ezample of the latter is packet-switched communications Becauie these ayatema may serve a wide variety of uten and becaue the nature or the data to be uu•ed ia determined by each individual Wier I U In addition to the functions involved in the procening of normal measage traffic procewa to handle modem communications must also addreu the following • U Interpretation of protocol layer Characteri1tic of modem traumiulona i1 the incorporation into the data etreaJD of control information required by the communications ayatem Thi• consists of bits which are added to the data ltream and referred to u protocol layers Each layer repraente information required to carry out a epecific communications function Figure 2 The ruultant bit stream is an amalgamation of the tra ftic ·being transmitted and all the protocol information To c ornctly interpret a modem's output these protocol bite must be identified and either removed or acted upon Unlike noiee in the analog world theae protocol bita eerve a function A major task or any modem proc eulng 'Item muat be to identify int erpret and act upon this noiae Juat as there are many dift'erent types of modem devices there • Jlan-maelaine intcracti1 e communior modem communications involve interactiona between a human and a computer Theae interactions often take the form of a query by the human the form of a command and the comnuter's reaponae I cation A significant percentage in • r EIOOf Non-matJG e form of modem • • 1 traf k _ • • PHYSICAL CONTROL LAYER LINK CONTROL LAYER NETWORK CONTROL LAYER TRANSPORT CONTROL LAYER TRAFFIC EO 3 3b 3 PL 86-36 50 USC 3605 FIG 2 TYPICAL LAYERS OF DIGITAL COMMUNICATIONS PROTOCOL 2nd laaue 1987 • CRYPl'OLOG • i-aw 11 91 1eRR'I' 11 HBY TJIA EJQMRR EJIWR iiJY QIU ¥ He eetfPftlte'I' 889RB'P I Io need only witnaa the ch809 in an analyiic orpnit' ation when eeparation criteria or 1ta traffic is incorrect t o appreciate the imnori nce of this function in our overallJ • • f8 eeo Dia la O I ·- I ' iflUIU led c ommunicationa requires at e •• ' lo rma ti o n p re eented to a tarlet analyst in · a form that he can readily compnhend The • • recopition that computer•to-oomputer • c ommwucationa are a potential source ot' intelligence haa added a new dimension to the · •• interpretation and display ot' intercepted c ommunicationa Now they may be in the Conn of computer terminal displays graphic --··-nal sonware can oe loaded on tbe ASTW presentations data filea etc t o J rov de pageprint of printable data streama ancf th'1a produce a level t f quality control at - Selection of duired traff c the i of collection • 'on in the is e r tracUng or data ------•- t o be developed I ·-------------- • • • • I • I • I • I • New methodologies will have I • I• I• I• • COLORCAST I• te-oee • I• • •· te 889 Once aiQd4 unications have been collected tLe -ta tit of interpreting the resulting bit atre i qtlirea a detailed understanding of th r i rious layers of paa 2ndlaauel98'1 • CRYPTOLOO • 0 Me ee PfRoMllf I • ---------1 12 • • • • le rtl IT tlrHBH I 111 eew r 81WHifil h8 8tH ¥ 1 I I I I Eo 3 3b c3 PL 86-36 50 use 3605 I EO 3 3b 3 8B811H'I' PL 86-36 S0 use 3605 communications protocol that have been superimpoeed upon the information beinr aent The complexity of theae prob ol layen varies greatly from one circuit to another ranging from the fairly atnightforward control • information that ia required on a dedicated circuit between a computer and a aingle printer to the eztremely intricate mechani1m1 employed - - - - - - - - - - - - - - - - when paeket-awitched communications are • f 9 088 0 Nloping prototype to tware paseecl from one network to another en rout e to Duriq the nelation proceas we have to their destination deve op prototype aoftware to int erpret protocol bit and tAl• convert the transmitted traffic into U COLORCAST hu approached the task of a feadable form While this aoftware is not correladn1 modem bit streams with established iat ended fJJ function u a production process it prowc ols in the following manner Joea provide a c ipability to produce sample output tliat can be uted in catalolfng modems ------------t in me • _ _ • Q g g Q JJ • le• eee Bwluatin commercial hardroare COLORCAST ia conducting a continuing evalliation of commercial hardware marketed to pncesa di ital communications • raniin1 from eialuations of varioua pneralpu poae prowc ol recognizers to t eating special communicationi circuit cards for am all c cftnputers Thia eft'ort ia directecl at identifing hardware Jhat may be applicable to our new or pl'GC881ing efforts eolleeuon009 I ________________ I _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ ____ _ • 1e eoo• Correlating int rwpud bit rea with the FJIO Uz I ___ • EO Tranafcrrirtfl apcri ntal ma • p ••n to prod tion Durinr the sampling and p talolfng of the environment epecific signals with a ·high intelligence pot ential are incount ered Whon it is VCDM IBM RECEIVER DISK 5Mbyte ASTW Voim Channel PRINTER 132 column Democlul•tor SPECTRUM PROTOCOL ANALVZER ANALVZER Block Diagram of COLORCAST MODEM sampler 2nd IAWI 1987 • CRYPl'OLOO • pap 13 81JEIIIBT lfldfBLfi '•' flttfO 88Mltfl' OIM NHIIIJ8 Otft l 801fflll'i8'f I EO 3 3b 3 PL 86-36 50 81 18ft8'f determined that further swstained collection or such communications is required a QRC collect ion package optimized for the collection or that specific signal is aasembled and the proc essing algorithms neceuary t o handle its prot ocols are implemented on an appropriate proceaor either in the field or at NSA Such QRC actions enable us t o provide a sustained collection procesaing capability of high-priority communicationa long before we will be able to field a general-purpose modem collection proceaaing system use 3605 rate digital carrie The rapid introduction of channel-level during the put several years is but tlle first step in thfa change Alreiuly IJ' tlP liand modems INTELSAT'S intermediate data rate carriera IDR and digital raaios iitb data rates in ezceu of 140 megabi '• per nd are in operation moa U • The ne decade will see the SIOINT syet em conti bally confronted with the introduction of new technologies which will ereate problpts io at least four areas e• eeo A priori information concerning a network's structure and its operating cbara• eteristics can greatly racllitate a collection efFort mounted against it Such information ia critical when dealing with the very complez and • potentially dynamic routing of packet-awitched networks-I FUTURE INTERNATIONAL COMMUNICATIONS U The world-wide change from analog t o digital communications is occurring at an increasing rate some forecasts have predicted that by the end of this century which is only 13 years away over 90% of all free world communications will be passed by high data Znd laue 1987 • CRYPTOLOO • page 14 8BelH 'P HMf JbB lJM eeMttflf 8tb HH8bB 8HL' t HO 00t fR • • EO 3 3b 3 PL 86-36 50 US C 3605 -------------------············------------been within the paat three years that the performance requirements for satellite networks have begun t o take ahape U The basic building block for voice video and data communication in ISDN is a 64-kilobit per second channel called a B channel This eame building block is uaed in ezisting digital telephony networks to tra naport pulae-eode modulated voice-band signals To achieve higher transmisaion rates several B channels can be concatenated to form a channel with a bandwidth in excea ot 64K bpa The resulting channel is called an H channel __ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 1 appean t o be t owarda t o the establishment of integrated services digital network• ISDNs These networks will carry voice data and video information within multlplezed data streama by means of digital microwave cable fiber optic and satellite transmisaiona The atructun of many of t oday'1 packet-lwitched networks baa been designed specifically t o facilitate the incorporation of ISDN technology An ISDN ia an end-t o-end digital network that uses uniform transmission signaling and operating procedures Ac c e• t o the network and its uaoci ated services will be throu1h a standard pb 'tical interface using existing telephone systems U The trend U The key t o ISDN is standards A committee or telecommunications organizations in Western Europe began work in 1979 to develop standards for ISDNI Today ISDN standards are bein1 further defined by the Consultative Committee on International Telephony and Telegraphy CCITTl an intem- tional standards organization with a mandate t o establish recommendations for endto-end performance interconnection and maintenance of world networks of telephony telegraphy and data communications This group bu already identified a number of fundamental standards of ISDN Interestingly though plannin1 for ISDNa hu been progreuing for at least seven years it has only CU In existing telephony networks signaling data for a communications channel la encoded within the channel while in ISDN it is carried in a separate aaaociated channel called a D channel A Bingle D channel can carry the signaling information for many B channels This technique of separating the signaling channel from the data transmission channels is called common channel signaling and is fundamental t o ISDN U A basic ISDN atandard is the baaic aceeaa interface Thia 144-Kbpa interface conaista of two 84 Kbps B channels for voice video and data transmission and one 16 Kbps D channel for signaling An alternate aceess interface for large organizations is the primary access interface For North America and Japan this is a 1 544-Mbpa interf'ace con isting of 23 64Kbps B channels for voice video and data transmission and one 84-Kbps D channel for signaling In Europe and moat of the rest of the world the interface is a 2 048-Mbps interface consisting of 30 64-Kbpa B channels for voice video and data and one 84-Kbps D channel for lignaling U ISDN provides tale flez ibility of aubmultiplexing channels for applications that do not require the full 64-Kbps circuit capacity It also supports packet awitching aa well as the circuit switching found in existing networks Theae capabilities provide great opportunity to maximize circuit capacity CONCLUSION E8 889t While the tranaition from analog to digital communications presents us with a set of difficult technical problems that must be solved if the SIGINT system is to continue t o 2ndluue 1987 • CRYPl'OLOC • pap 15 BR8RRIP JhtlHBbB ¥tA eeMHff 811MfHBll8 0HL7 ' f6 C8tf1Plbfc8'P I EO 3 3b 3 PL 86-36 50 USC 3605 I Non - Responsive • function effectivelv nC ne is insurmountable ftCltBT I I