CDMA SECURITY

-AN INTELLIGENCE

GUIDED BY- PROF. BHARATI S. AINAPURE

PRESENTED BY-MUKESH KUMAR

INTRODUCTION

Wireless communication of information.

Originated from military applications and cryptography.

For military communications where information transmission heavily

relies on wireless networks (for instance, from aircraft to aircraft, from

aircraft to ground control center, etc.), security and reliability of the

wireless communication systems is of number one priority, especially in

national defense and emergency response to abrupt enemy attacks

SECURITY OVERVIEW

Protecting corporate network assets is an on-going task for IT

professionals.

Some of the top security issues:-

1). Unauthorized systems and network access.

2). Theft of intellectual property and confidential business

information.

3). Internal and external sabotage .

NETWORK AND TECHNOLOGY OVERV IEW

It has Same components and technology used in corporate

network.

Difference between these two is found only in the access

network. In access network high security and access protocols

become paramount.

CDMA2000 1XRTT AND 1XEV-DO

More mobility , secure, high-speed access , and an extension of

applications across the enterprise.

Third-generation (3G) wireless networks, known as CDMA2000

The first phase of CDMA2000 is called 1xRTT.

a). Maximum theoretical data rates of 144 Kbps (downlink)

and 144 Kbps (uplink) ,Excellent voice capacity .

CDMA2000 1XRTT AND 1XEV-DO

Cdma2000 1xEV-DO Revision 0 (Rev. 0).

a). Increases the downlink maximum theoretical data rate to

2.4 Mbps, with an average data rate between 400 and 700 Kbps.

b). Supports Quality of Service (QoS) .

c). boosts the maximum theoretical uplink speed to 1.8 Mbps

(average 500–800 Kbps).

ACCESS NETWORK

Two types of access networks:- 1xRTT and 1xEV-DO .

It is the mobile station’s entry point into the network .

It maintains the communications link between the mobile station

and the core network.

It facilitates security by allowing only authorized mobile stations

to access the network.

ELEMENTS OF ACCESS NETWORK

The AN is composed of the following elements: -

a).Base Transceiver Station:-physically composed of antennas and

towers.

b).Packet Control Function:-maintains the “connection state”

between the access network and mobile stations.

c).Radio Network Controller/Base Station Controller:-packet

transmission on the air interface and manage connection between BTS’s.

ELEMENTS OF ACCESS NETWORK

CORE NETWORK

Acts as the gateway between the access network and the Internet

or enterprise private networks .

It provides authentication, authorization, and accounting (AAA)

services, provides access to network services, and manages IP

addresses .

ELEMENTS OF CORE NETWORK

The core network comprises the following elements:-

a).PDSN/Foreign Agent:-The PDSN is the gateway between

the access network and the core network.

b).AAA/Home Agent:-The AAA and the home agent (HA)

are used for authentication, authorization, and accounting for data

services .

SECURITY-CDMA NETWORK

The security protocols with CDMA-IS-41 networks are among the best in

the industry.

By design, CDMA technology makes interpretation of data very difficult.

Unique to CDMA systems, is the 42-bit PN (Pseudo-Random Noise)

Sequence called “Long Code” to scramble voice and data.

On the forward link , data is scrambled at a rate of 19.2 Kilo symbols per

second (Ksps) and on the reverse link, data is scrambled at a rate of 1.2288

Mega chips per second (Mcps).

SECURITY-CDMA NETWORK

CDMA network security protocols rely on a 64-bit authentication

key (A-Key) and the Electronic Serial Number (ESN) of the mobile

. The key factor for CDMA network is:-

Authentication:-The mobile uses the SSD_A and the broadcast

RAND* as inputs to generate an 18-bit authentication signature

(AUTH_SIGNATURE), and sends it to the base station.

SECURITY-CDMA NETWORK

Voice, Signalling, and Data Privacy:-The mobile uses the

SSD_B and to generate a Private Long Code Mask(derived from an

intermediate value called Voice Privacy Mask.

By design, all CDMA guided devices use a unique PN (Pseudo-

random Noise) code for spreading the signal, which makes it

difficult for the signal to be intercepted.

AIR INTERFACE (PHYSICAL LAYER)

Mobile stations rely on radio technology to access the network.

Security is of concern when using radio technology, but with the

advances in radio technology.

So several air interface security mechanisms have been

developed to keep signals secure while increasing access

capability.

AIR INTERFACE TECHNOLOGIES

Three types of technology :

AIR INTERFACE SECURITY BENEFITS

CDMA security works on (direct sequence spread spectrum)DSSS technology.

DSSS technology employs techniques that deliberately distribute or “spread”

data over a frequency domain.

The low probability of interception, demodulation difficulty, and anti-

jamming/interference benefits of DSSS.CDMA technologies are why the

military has used it for so many years.

This is also why CDMA technology is inherently more

secure than competing wireless technologies.

EXAMPLE :

.These are four mutually

orthogonal digital signals.

.These vectors will be

assigned to individual users

and are called the "code",

"chipping code" or "chip

code

EXAMPLE :

Each user is associated with a different code, say v.

ASSUMPTION: 1).If the data to be transmitted is a digital zero, then the

actual bits transmitted will be –v. and,

2). if the data to be transmitted is a digital one, then the actual bits

transmitted will be v.

.so If v=(1,–1), and the data that the user wishes to transmit is (1, 0, 1, 1)

this would correspond to (v, –v, v, v) which is then constructed in binary as

((1,–1),(–1,1),(1,–1),(1,–1).

EXAMPLE

If sender0 has code (1,–1) and data (1, 0, 1 ,1), and sender1 has

code (1,1) and data (0,0,1,1), and both senders transmit

simultaneously.

Because signal0 and signal1 are transmitted at the same time into

the air, they add to produce the raw signal:-(1,–1,–1,1,1,–1,1,–1) +

(–1,–1,–1,–1,1,1,1,1) = (0,–2,–2,0,2,0,2,0).

S t e p E n c o d e s e n d e r 0

E n c o d e s e n d e r 1

0 v e c t o r 0 = ( 1 ,– 1 ) , d a t a 0 = ( 1 , 0 ,1 , 1 ) = ( v, –v, v, v )

v e c t o r 1 = ( 1 ,1 ) , d a t a 1 = ( 0 ,0 , 1 , 1 ) = ( – v, -v, v, v )

1 e n c o d e 0 = ve c t o r 0 . d a t a0

e n c o d e 1 = v ec t o r 1 . d a t a 1

2 e n c o d e 0 = ( 1, – 1 ) . ( 1 , –1 , 1 , 1 )

e n c o d e 1 = ( 1 ,1 ) . ( – 1 , –1 , 1 , 1 )

3 e n c o d e 0 = ( (1 , – 1 ) , ( –1 , 1 ) , ( 1 , – 1 ) ,( 1 ,– 1 ) )

e n c o d e 1 = ( ( –1 , – 1 ) , ( – 1 , –1 ) , ( 1 , 1 ) ,( 1 , 1 ) )

4 s i g n a l 0 = ( 1 ,– 1 , – 1 , 1 , 1 , –1 , 1 , – 1 )

s i g n a l 1 = ( –1 , – 1 ,– 1 , –1 , 1 , 1 , 1 , 1 )

S t e p D e c o d e s e n d e r 0

D e c o d e s e n d e r 1

0 v e c t o r 0 = ( 1 ,– 1 ) , p a tt e r n = ( 0 ,– 2 , –2 , 0 , 2 , 0 , 2 , 0 )

v e c t o r 1 = ( 1 ,1 ) , p a tt e r n =( 0 ,–2 , 2 , 0 , 2 , 0 , 2 ,0 )

1 d e c o d e 0 = v ec t o r 0 . p a tt er n

d e c o d e 1 = v ec t o r 1 . p a tt er n

2 d e c o d e 0 = ( (0 , – 2 ) , ( –2 , 0 ) , ( 2 , 0 ) ,( 2 , 0 ) ) . ( 1 , – 1 )

d e c o d e 1 = ( (0 , – 2 ) , ( –2 , 0 ) , ( 2 , 0 ) ,( 2 , 0 ) ) . ( 1 , 1 )

3 d e c o d e 0 = ( (0 + 2 ) , ( –2 + 0 ) , ( 2 + 0 ) ,( 2 + 0 ) )

d e c o d e 1 = ( (0 – 2 ) , ( –2 + 0 ) , ( 2 + 0 ) ,( 2 + 0 ) )

4 d a t a 0 = ( 2 , –2 , 2 , 2 ) , m e a n i n g ( 1 , 0 , 1 , 1 )

d a t a 1 = ( – 2 , –2 , 2 , 2 ) , m e a n i n g ( 0 , 0 , 1 , 1 )

EXAMPLE:

ENCODER SIDE DECODER SIDE

Efficient Practical utilization of

Fixed Frequency Spectrum.

Flexible Allocation of Resources

Privacy protection in CDMA

due to anti-jamming capabilities of

PN sequences

We can change somewhat the

flow rate of voice and signal by

knowing the ESN AND MIN.

ADVANTAGE AND WEAKNESS

ADVANTAGE WEAKNESS

FUTURE AND RESEARCH

Continue work on verifying composition of security tunnels

Currently thinking about attacks so now a days AES algorithm

is used.

Add the capability to reuse tunnels.

seemed easy at first, but may require some major restructuring

of the design.

RESEARCH PLAN

iRespond is a device that will provide an immediate response to

a certain location.

CONCLUSION

It provides secure wireless communication.

Its uplink and downlink communication , make it better than

others.

It is hard to detect , decode.

Technology makes it better than other.

It is better , but it is still secondary.

REFERENCES

Viterbi, Andrew J. (1995). CDMA: Principles of Spread Spectrum Communication

(1st Ed.). Prentice Hall PTR. ISBN0201633744. 

"Telecom-Resource-CDMA“ . Telecom-Resources. Undated.

http://www.freewebs.com/telecomm/cdma.html. Retrieved 2006-04-09. 

Lohninger , Hans (2005-12-17). "Direct Sequence CDMA Simulation". Learning by

Simulations. http://www.vias.org/simulations/simusoft_dscdma.html. Retrieved 2006-

04-09. 

Authentication and Security in Mobile Phones by Greg Rose, Qualcomm Inc.,

Australia

THANK YOU !