Secure Communication Tests Carried out With

Next Generation Narrow Band Terminal in Satellite

and Local Area Networks

Orkun DiLLi Air Force Vocational Training School

Department of Technical Programs Izmir, TURKEY

odilli@tekok.edu.tr

Murat KOYUNCU Atilim University

Information Systems Eng. Ankara, TURKEY

mkoyuncu@atilim.edu.tr

Abstract-Communication becomes more and more important

day by day and especially secure communication from one end to the other holds a vital place in our daily life. Developed countries

which are aware of this fact has started to carry out serious studies on secure communication from one end to the other. One of the

most important studies is the project which appeared as FNBDT (Future Narrow Band Digital Terminal) at first and was renamed as SCIP (Secure Communication Interoperability Protocol) later on.

FNBDT (Future Narrow Band Digital Terminal) or SCIP (Secure Communication Interoperability Protocol) is a communication protocol which is a result of secure communication need of different network devices in contact with each other. The

main purpose of the protocol is to provide the new generation terminals which are source of transmission with secure communication with each other through different networks using narrow band.

National and international studies on FNBDTISCIP has focused on three main points; FNBDT protocol, SCIP protocol and codes of MELP (Mixed Excitation Linear Prediction)

Studies about implementation of FNBDTISCIP are much fewer

than theoretical studies on the matter. Some tests of FNBDTISCIP on satellite and local Networks are carried out to overcome this lack of implementation. It is aimed to set up calls on different Networks, to check transmission of voice and data with and without any loss

and to find out the limits with these tests. Results of these tests were

declared before. In this study, some tests on satellite and local Networks are carried out; as a result, values about call set ups and limits of voice and data transmission are compared with ITU (International Telecommunications Union) standards.

Keywords-component; Secure Communication, Satellite communication Network, Local Network, FNBDT, SCIP.

978-1-4673-6396-9/13/$3l.00 ©2013 IEEE 493

Nursel AK�AM Gazi University Elect.-Elec. Eng.

Ankara, TURKEY ynursel@gazi.edu.tr

Ender OdUSUJ Air Force Vocational Training School

Department of Technical Programs Izmir, TURKEY

eogusl u@tekok.edu.tr

I. INTRODUCTION

Today, there are different telecommunication networks such as ISDN, PSTN, and GSM. When we look at the military networks, we see that usually narrow-band radio and satellite based communication systems are used. Interoperability between these networks is usually established. But, in a scenario that uses several different networks, it is not possible to provide a seamless, end-to-end secure communication.

Figure 1: Secure communication over different networks

Today, crypto devices depend on the technology used at the underlying network and it is not possible to use a common crypto technology in all communication networks. For example, a crypto device used in ISDN networks differs from another crypto device used in PSTN networks. If a subscriber wants to communicate encrypted with another subscriber on another network technology, Subscribe to different state-of-the­art encrypted with another network wants to discuss this, as can be seen in Figure 1; the conversation between the two networks is being decrypted and then encrypted again. This process

creates a big communication safety problem. Another problem that came up with the emergence of a large number of diffe�ent technologies is that you have to use a large number of term mal devices that are specific to networks. So, there are many different terminal devices on a manager's desk nowadays. Simplification of this confusing situation emerges as an important need [1-2].

Developed countries and international organizations, which are aware of the problem, have done serious research in the last ten years on development activities about interoperability in the form of national or international partnerships.

FNBDT (Future Narrow Band Digital Terminal) or its new name SCIP (Secure Communication Interoperability Protocol), is a communication protocol which is discussed above that allows secure communication between devices engaged in different networks. The main objective of the protocol is to provide a secure communication between new generations of terminals using different networks with one another over the narrow band.

International and national FNBDT/SCIP studies to this date are collected under three main topics. These are; studies about FNBDT [3-8], SCIP [9], and MELP (Mixed Excitation Linear Prediction, mixed Linear Prediction) encoding [10-11].

Although theoretical studies on FNBDT/SCIP seem to be satisfactory, studies on implementation seems to be fewer. Some tests of FNBDT/SCIP on satellite and local Networks are carried out to overcome this lack of implementation. It is aimed to set up calls on different Networks, to check transmission of voice and data with and without any loss and to find out the limits with these tests. Results of these tests were declared before [12-16]. In this study, some tests on satellite and local Networks are carried out; as a result, values about call set ups and limits of voice and data transmission are compared with ITU (International Telecommunications Union) standards and interpreted.

The remaining of this paper is organized as follows. FNBDT/SCIP signaling basics, basic information about practice tests and the networks in which the implement�tions are performed are described in Section 2, 3 and 4, respectl\,:ely. The fifth section contains application limit values and duratIOns achieved in the tests. The paper is completed with the conclusion in the sixth section.

II. FNBDT/SCIP SIGNALING BASICS

FNBDT/SCIP signaling consists of call set-up and control signals. Call Set-up signaling includes Competence, Parameter/Certificate, F(R) (Forward & Reverse, Crypto Sync, and Communication Control Signaling includes Notification, Mode Change and Sync Set-up subjects.

FNBDT/SCIP signaling begins with eight byte SOM (Start of Message) and ends with eight byte EOM (End of Message) as shown in Figure 2.

Frames between SOM and EOM are described as super frames. Each super frame consists of forward error correction (FEC) and cyclic redundancy checks (CRC).

494

Acknowledgement and Negative Acknowledgement (ACK and NACK) are used in order to remove errors left from FEe.

Each frame consists of 20 bytes including 1 frame number, 13 messages, 4 FEC and 2 CRe. Each frame group made up of these frames is comprised of at least 1 and at most 127 frames.

In FNBDT / SCIP signaling, first, it is checked whether the last received frame is ESCAPE or REPORT when EOM is received. If it is not, a report is prepared and sent for the frames received so far. ESCAPE message is a concept related to the usage of bandwidth, on the other hand, REPORT message is a concept related to the error rate approvals.

Similarly, another message among message types encountered in FNBDT/SCIP signaling is RESET which is used to synchronize the transmission layer again when necessary. RESET message zeros the frame numbers and only one RESET message is sent between a SOM and EOM.

-=== -SOY fRAME CI'&.M SG. EOM

---SOM M.PORT roM

- ====------ = = -SOM flUMf fltlMf flU.Mf PItMJCIO". EOM

--$OM IlEPORT EOM

- ­SOM REPORT fOM

--SOli RtPORT roM

- = === -sou. fRAME. FRAME CRY.I'fN.. fOM

--SOM IlEJIORT fOfIfI

-EOII

------ ------ -fl..LEft. f1LLEft fLlfft FJlL£R

-= - ------ - = - ------. START SYHC.MNG. "'UP SYHc. ... NG. YELP

sou: 9 EOU:9 FRAME: 73 CPB.USG.: 1 PRM.lCRT.: 1 FIR): t CR'f.SYN: 1 REPORT: • FILLER: 12 START: 1 TOTAL MESSAGE: 111

FNBDTlSCIP

CALL SETUP

SIGNALLING

C�II Sfotup Ourl-tion : 1.182 sec.

Figure 2: FNBDTISCIP Call Setup Signaling

In FNBDT / SCIP signaling, the terminals send each other Capabilities Message as the first step of communication signaling. Owing to this message, terminals rea�h an agreement on how they will work (open or closed modes) m harmony and if communication will take place in safe mode, the selection of the appropriate key list will accordingly be possible. The fir�t message timer starts when Capabilities Message is sent and thIS timer provides the connection to time out in case a FNBDT/SCIP compatible message isn't received from the other side. At the end of timeout, the situation is an invalid connection.

At the end of the first messaging, mutual certificates and F(R) 's have to be exchanged in order to establish �NBDT / SCIP connection and to create traffic key If secure communication decision has been made. Out of these, sending the certificate occurs with Parameter/Certificate message.

F(R) is a message covering a number information of key pack (the key type, length, etc.), F(R) length and itself. Parameter/certificate message must be sent before F(R) message is forwarded.

Another step in establishing FNBDT / SCIP connection is the exchange of crypto synchronization messages .

. Traffic �ey

is formed with the replaced certificate and F(R) mformatIOn

and with the help of this key; test pack is encrypted and turned into Crypto Synchronization Message.

A nwnber of signaling definitions are available related to subjecting the established connection to changes after connection signaling. The purpose of connection control signaling might be terminating the connection for any reason, changing the current practice, alerting the other terminal and/or ensuring the crypto synchronization from the beginning. There are four different messages in connection control signaling. These are Notification, Mode Change Request, Mode Change Response and CryptoSync messages.

Mode changing process occurs in two different ways which are the demand and the reply to it and can only be possible when both terminals are in secure application traffic.

Five different calls are available for secure sound. These are [3]:

• Secure 2.4 kbps MELP coded Voice - Blank & Burst (B&B), Discontinuous Voice Transmission (DTX)

• Secure 2.4 kbps MELP coded Blank & Burst (B&B), Force Continuous Voice Transmission (FCT),

• Secure MELP coded Voice-Burst without Blank (B w/o B), DTX,

• Secure MELP coded Voice -Burst without Blank (B w/o B), FCT,

• Secure, Advanced Multi-Band Excitation (AMBE).

Two types of secure voice calls, which are Blank & Burst practical MELP and Burst w/o Blank, can be made in FNBDT/SCIP.

Crypto synchronization data is written on MELP coded sound information produced periodically at 2.4 kbps by the terminal for the continuity of crypto synchronization in a FNBDT/SCIP compatible terminal. This process is called "B & B" (Blank and Burst) protocol and minor decrease in sound quality is experienced in this application due to deleting the sound information and entering the crypto information instead from time to time.

Despite Blank & Burst frame set consists of 24 frames, Burst w/o Blank (B w/o B) application consists of 25 frames. Therefore, required channel capacity for Burst w/o Blank application is more than 2.4 kbps (overhead). At the same time, the sound quality is better than B&B because crypto synchronization information is not written on MELP encoded sound information.

The emerging structure in open MELP voice call service conversation is just the same as it is in B&B. Message is formed again with frame sets consisting of 24 frames, one of which is SM (Synchronization Management) frame. Because encryption is not performed here, the message is sent by filling the part of SM frame after the header with zeros here in the SM frame part of.

In addition, all FNBDT/SCIP compatible terminals communicating whether in secure mode or not are expected to support DTX and FCT conditions. Of these, DTX expresses the

495

principle of forming and sending frame groups as long as the user of the terminal speaks, and interrupting sending when the user stops speaking whereas FCT expresses the forming and sending of frame groups during the time the terminal user stops speaking, which is the continuous operation of MELP coder, during a voice call.

FNBDT/SCIP data communication supports two types of service. These are the "RT (Reliable Transport, Secure Transfer)" Asynchronous Data Service and "GT (Guaranteed Throughput, Guaranteed Work)" Asynchronous Data services. In RT Asynchronous Data service, a data call is initiated using the same signaling mechanisms that are used in secure voice service and the channel capacity is used with 70% efficiency. In GT Asynchronous Data service is a service that uses the entire capacity of the channel [1, 7-8].

III. BASTC INFORMA nON ABOUT PRACTICE TESTS

FNBDTISCIP Emulator: Software to test the work performance of vehicles in different scenarios and cases within the Lab. Interface of Emulator program is shown in Figure 3.

"" FNBDT Emulator �(Q]rg)

I P N etWOlk r nitiMzed Conned to: IP:192.168_3_3:1600 Lli Conned Svoccenful Conne<:ted to: 192.168.3.3:1600 · Sent C�jties ElCChange men� • Received Capabilities EKC� message "" ENSOT Secure Type 1 Voice · Sent Pauwnetels Ceft�icate message • Rec� ParemelefS Cerlific ... te mess� .. ENRRT VOCe- Secure 2400 MEl P Blonk ,:,od BtHd fCT •• ENSOT Securily level: Secret • Sent FIR) message • Received F(R) message • Sent Clypto*ync message • Received CWptosync message ENSOr Connect 5ucceufU/

ICONNECTED

Inte,f5Ce:

I'p :=oJ Address 1192.168.3.3:1600

1[-···· :,�···· -iI

� Qi,�, 1 Loopb�k I

I Change ENBor Mode... I

I SecureOia I

Figure 3: User Interface of FNBDTISCIP Emulator

FNBDTISCIP Tester: A part of FNBDT/SCIP Emulator program. It is used to check and control the FNBDT/SCIP communication between terminals. The interface of the program is shown in Figure 4.

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�g.'l(l co.o -:':�. _� � j :.::t;'.;;'OIiR.I_lt\ ltj j �

.... ......... ...... ......

.. " ..... ............ n ........... ..

....... 11 ................. , ....... . ..

.. " .. " . .. ' . ........ .... .. ...... .. .. "n ..... ............... . .. .. . . ... .... ...... .... .. .. .. .. ... .......................... " U II ...... ................ . , .... .. .. .. .. .. . . - .. .... . , .. ...... .. .. .... .. .. .. n ..... .......................... .. ,." .. _ .................... "'""uo ...... _ ...... .. ul . ..... • ...... uOC

- " ..... ..

r.f"' "It ..... . , ......... n ........... ..

.. .... ... .. .. ... . . .... . ...... ... . .. .. " ""- . . ...... ... . . . ..... .. ..... ..

. . .... ... ... . .......... . "It ..... ........................ .. ...... . " ........ .. "" .......... .. .. .... ..... . ... .... .... . ..... .. ...... .. . . .. .. .... . . ..... .... ........ .. ...... .. "1.1 ... " . ....................... ..

.. _ 101.1 .. ., . .... 111 ................ ... 111:

.. - .. .... - ...... .... . .

......... . ..... ................ ......

.. .... oM .......................... ..

. ... .. ... . . .... .. ..... . .. .. . ... .. .. ..

.. . . .. ... .... .. ...... " ...

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. ......... , ..... "" .. .. -.

..u ...... .............. .. .... ..... o ....... " .... " . ...... .. .. .. u .. _ .......................... .. .. ....... H ........... , .... .. .. .... ..

Figure 4: FNBDTISCIP test module interface

.

Bit Error Rate (BER): The average of error data bits within a duration to the total bit rate.

Data Loss: The average of error bit or byte rate to total data. In the application of simulator, bits for bit loss and groups of eight bits for byte loss are restricted at random to cause data loss.

IV. THE NETWORKS PRACTICE TESTS ARE PERFORMED

FNBDT/SCIP tests are carried out for call setup, B&B Secure Voice Communication, Bw/oB Secure Voice Communication, RT Reliable Data Communication, GT Guaranteed Data Communication sections and bit and byte error rate is detennined.

A. Satellite Network

Satellite

LAN-2 LAN -1

Figure 5: Satellite Network/or FNBDTISCIP Application

Test mechanism achieving satellite communication between two users is established and tests are carried out in real environment as in Figure 5. Test mechanism consists of;

• TURKSAT-2A satellite,

• FNBDT/SCIP Terminal starts the call,

• FNBDT/SCIP Test Device tests the communication environment,

• Local Area Network with Ethernet Swich and Two Cisco Routers,

• Two X Band Modem.

B. Local Area Network

IP test mechanism is established to investigate FNBDT/SCIP protocal's effect on Local Area Network in LAB as in Figure 6. Test mechanism consists of;

• FNBDT/SCIP Terminal starts the call,

• FNBDT/SCIP Test Device tests the communication environment,

• FNBDT/SCIP Terminal answers the call,

• 2 Local Area Network with 3800 and 2600 serial 2 Cisco Routers.

496

LonJ Arel :\"ernrk - I

Figure 6: Local Area Network/or FNBDTISCIP Application

V. IN PRACTICE TESTS LIMIT V ALUES AND TIMES

FNBDT/SCIP protocol which was developed to make secure end-to-end communication is tested from different angles on Satellite and Local Area Network with emulators. Limit values and durations obtained from the tests are stated in Table 1.

Limit values in Table 1 shows the maximum error/drop rate of call set-ups. Comparing the limit values from the tests to standards, we can say that;

• Duration of call set-up in both Satellite and Local Area Network is less than standards, the more the error and drop rate the more call set-up duration takes place. Limit values from the Local Area Network tests are better than standard limits, but the limit is passed by Satellite Network values.

• Limit values of B&B and Bw/oB Voice, RT and GT Communication from FNBDT/SCIP tests on Satellite and Local Area Network are within the tolerance rate and even better.

VI. RESULTS

Limit values are obtained by testing FNBDT/SCIP Protocol on satellite and local networks separately. In this paper, results from this research has compared with each other and interpreted. Consequently;

• It takes less time to set up normal calls than Satellite Network in Local Area Network.

• Local Area Network and Satellite Network have the same values in call set-up with bit error rate and call set-up with drop byte rate.

• The duration of call set-up in Satellite Network is less in call set-up with bit error rate and call set-up with drop byte rate tests.

TABLE/, FNBT/SCIP TESTS ON SATELLITE AND LOCAL AREA

Satellite Local Area

Practice Tests Definition

Duration Duration

Threshold (sec.)

Call Set-up 111

Normal Call Set-up Messages 7,182

Call Set-up With Bit Error Rate 0,05 33,5

Call Set-up With Drop Byte Rate 0,05 106,953

Call Set-up With Drop Bit Rate 0,01 74,156 B&BIBw/oB Voice

Communication

Effect of Bit Error Rate 0,1

Effect of Drop Byte Rate 0,1

Effect of Drop Bit Rate 0,1

RT Data Communication

Effect of Bit Error Rate 0,02 105,675

Effect of Drop Byte Rate 0,03 851,266

Effect of Drop Bit Rate 0,03 601,625

GT Data Communication

Effect of Bit Error Rate 0,1 1,648

Effect of Drop Byte&Bit Rate 0,1

• The call was not set without the SOM message in call set-up tests on both networks.

• Results from B&B and Bw/oB Voice Communication Tests have similar values.

• In RT Data Communication tests, local network is more effective in bit error rate and drop byte rate.

• Limit values from GT Communication Tests are similar like B&B and Bw/oB Voice Communication tests' results; and data transportation with bit error on Satellite Network takes less time.

REFERENCES

[1] O. Bozoklu, "In The Scope of Secure And Interoperable Communication, Turkey's Approach to the Crypto Stand arts In NATO/SClP (An Implementation on TASMUS), Ankara, Kara Harp Okulu Savunma Bilimleri EnstitusU, pp. 99-110, 133-139, 2007.

[2] O. Dilli, S. Nazlibilek, O. Bozoklu, M. Koyuncu, and N. Ak9am, "Providing End-to-End Secure Communications on Different Networks", Network and Information Security National Symposium-2, EMO, Girne, May 2008.

[3] Daniel, E. J., Teague K. A., Sleezer R., Brewer J., Raymond W. J., Beck, J., Hershberger, "The Future Narrowband Digital Terminal", Proc. 45th IEEE Midwest Symposium on Circuits and Systems MWSCAS '2002, Tl-589-592, StillwaterlTulsa, OK, (2002).

497

Threshold (sec.)

Call set-up time in

107 Satellite

Messages 1,735 Communication Average: 19,215 sec.

0,03 105,641 Maximum: 56,9 sec.

0,03 114,453 [17]. Call set-up time in

Local Area Network Average: 7,5-8,45 sec.

Maximum: 180 sec.

0,01 96 [18].

0,1

0,1

0,1 Bit Error and Drop Byte Rate Tolerance

0,02 81,562 BER 10" _10-4 Data Loss 10-5 - 10-3

0,03 796,296 [19-24].

0,001 659,094

0,1 2,001

0,1

[4] Daniel E. 1., Teague K. A., "Simulation of FNBDT over Internet and 3G Wireless Networks", Proc. 45th IEEE Midwest Symposium on Circuits and Systems MWSCAS '2002, 330-333, 4-7 (2002).

[5] Gauche F., "An Approach of the Future Narrow Band Digital Terminal Protocol", Seventh International Conference on Computer Science and Information Technologies, 457--462, Yerevan, Armenia, (28) 2 (2009).

[6] Daniel E. J., Teague K. A., "Performance of FNBDT and Low Rate Voice (MELP) over Packet Networks", Proc.35th Asilomar Conference on Signals, Systems, and Computers, 1568-1572, Pacific Grove, California, 4-7 (2001).

[7] O. Oren, "Future Narrowband Digital Terminal", Ms. Thesis, Adapazan, Sakarya University, Fen Bilimleri EnstitusU, pp. 3-54, 2005.

[8] General Dynamics Communication Systems, FNBDT Signaling Plan (Revision 1.1), Needham, EylUI (1999).

[9] Alvermann J. M., Kurdziel M. T., Furman W. N., "The Secure Communication Interoperability Protocol (SClP) over An HF Radio Channel", MILCOM 2006, 1--4 (2006).

[10] Daniel E. J.,Teague K. A., "Federal Standard 2.4 kbps MELP Over IP", Proc.43rd. IEEE Midwest Symp. On Circuits and Systems, 8 (11): 568-571 (2000).

[11] Tan E.e., Teo T.T.,"Real-Time implementation of MELP Vocoder", Journal of The Institution of Engineers, Singapore, Vol. 44 Issue 3, pp. 38-58,2004.

[12] Dilli, 0., Ak9am, N. and Koyuncu, M., "Application of FNBDT/SCTP Protocol on Local Area Network And Determination of Limit Values", J. Fac. Eng. Arch. Gazi Univ., Vol 25, No 2, pp. 275-283, (2010).

[13] Dilli, 0., Ak9am, N., Koyuncu, M., "Determining the Limit Values in End-to-End Secure Communication within Satellite Network with FNBDT/SCTP", Energy Education Science and Technology Part A-

Energy Science and Research, Volume 29, Tssue I, 627-642, April (2012).

[14] Dilli, 0., Ak9am, N., M., Koyuncu, "Radyo Link ve Uydu Aglan Ozerinde Gelecek Nesil Dar Bant Terminal ile Yapllan GUvenli Haberle�me Test Sonu91an ve Degerlendirilmesi", 5th International Conference on Tnformation Security & Cryptology, TSC TURKEY, Ankara, May (2012).

[15] Dilli, 0., "Comparison of Test Results of Secure Communication Performed on the Local Area and Radio Link Networks with the Next Generation Narrow Band Terminal", Conference on Electncal And Electromcs Engineering, ELECO 2012, Bursa, 29 Nov.-I Dec. (2012).

[16] Dilli, 0., "Next Generation Narrowband Terminal Device Testing on Different Networks And Obtaining of Communication Boundary Limits", Ph. Thesis, Gazi University Institute of Science, Ankara, pp. 1-18, 27-60, 118-133, (2011).

[17] ITU, "Performance Enhancements Of Transmission Control Protocol Over Satellite Networks", TTU-R Recommendation S.1711 (0112010), 24-29 (20 10).

[18] ITU, "Call Processing Performance For Voice Service in Hybrid Ip Networks", ITU-T Recommendation Y.1530 (1112007), pp 4-6, 21-25, November 2007.

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[19] ETSI, "Satellite Earth Stations and Systems (SES); Broadband Satellite Multimedia; IP Interworking over satellite; Performance, Availability and Quality of Service", ETST TR 102 157 V1.1.1 (2003-07), France, 57-61 (2003).

[20] ETSI, "Satellite Earth Stations and Systems (SES); Broadband Satellite Multimedia (BSM); QoS Functional Architecture", ETST TS 102 462 V1.1.1 (2006-12), France, 43-44 (2006).

[21] ETSI, "Satellite Earth Stations and Systems (SES); Broadband Satellite Multimedia (BSM); Performance Parameters", ETST TS 102 673 V1.1.1 (2009-11), France, 22 (2009)

[22] ITU, "Allowable Bit Error Ratios at The Output of the Hypothetical Reference Digital Path for Systems in The Fixed-Satellite Service Using Pulse-Code Modulation for Telephone", ITU-R Recommendation S.522-5 1-2 (1994).

[23] ITU, "Availability objectives for hypothetical reference circuits and hypothetical reference digital paths when used for telephony using pulse code modulation, or as part of an integrated services digital network hypothetical reference connection, in the fixed-satellite service operating below 15 GHz", ITU-R Recommendation S.579-6, 1-2 (2005).

[24] ITU, "Allowable Bit Error Ratios at The Output of the Hypothetical Reference Digital Path for Systems in The Fixed-Satellite Service Using Pulse-Code Modulation for Telephon", ITU-R Recommendation S.614-4, 1-15 (2005).