0 Encryption Problem In WiMAX

Encryption Problem In WiMAX With the improvements of Wimax (IEEE 802.16e standard), it supports for Advance Encryption Standard (AES) cipher, actively giving strong support for confidentiality of data traffic. Like the Wi-Fi (802.11) specification, management frames are not encrypted, permitting an attacker to collect data about subscribers in the area and other potentially sensitive network characteristics. (Joshua Wright,Dec 12 2006)

I will conduct research and propose the possible encryption technique to make the communication through WiMAX network more secure so that the attacker cannot access the information regarding the user or the service provider. I have to discuss about the management frames and suggest solution for it to give better quality of service.

0 Authentication Problem in Wimax Technology

Authentication Problem In WiMAX A primary standard in WiMAX (802.16) networks is that each Subscriber Station (SS) must have a X.509 certificate that will exclusively recognize the subscriber. The use of X.509 certificates makes it difficult for an attacker to spoof the identity of subscribers, adding sufficient protection against theft of service. A basic problem in the authentication mechanism used by WiMAX's is privacy and key management (PKM) protocol is the lacking in authentication of base station (BS) or service provider. This makes WiMAX networks vulnerable to man-in-the-middle attacks, exposing subscribers to various confidentiality and availability attacks. (Joshua Wright,Dec 12 2006)

According to this above authentication problem I will research and find out that how we can put X.509 or relevant certificate to subscriber station so that it uniquely identify the subscriber as well as provide more security to the network against the usage theft. I also have to research about the man-in-the-middle attack so that we can make it more secure and reliable. I have to research and discuss about the private key management protocol and find out the solution to replace it with another protocol or suggestion.

0 Water Torture Threats to Wimax Technology

Threat of Water Torture in Wimax Technology Threats are very common to the wireless networks and the Wimax technology is not the one that still safe for wireless communication. A common threat to wimax arises from the water tortureattack, in which an attacker sends a series of frames to drain out the receiver’s battery. Additionally, attacker with a properly positioned Radio Frequency (RF) receiver can interrupt the messages sent through wireless, and therefore a security mechanism in the design is required.
Current security mechanisms do not address well in IEEE 802.16a Mesh modes network, which lead into new security threats, such as the reliability of the next-hop mesh node. Introducing mobility in IEEE 802.16e standard will make the attacker’s life easier. As the physical location of the attacker is not an issue, management messages are more at risk than in IEEE 802.11. Therefore, it is important to maintain a secure connectivity while a mobile Subscriber Station (SS) shifts between wimax Base Stations. (D Johnston, J Walker, 2004)
An attacker can easily write to a radio frequency channel with the help of properly configured Radio Frequency transmitter to build new frame, capture, change, and retransmit frames from authorized station. The design is required to ensure a data authenticity technology. It is also likely to resend a valid, already sent frame unchanged. In case of long distance transmission, radio interference and distance may possibly allow an attacker to alter and selectively forward frames, in a situation where two authorized stations are not able to contact directly with each other. For that reason, the design is required to detect replayed frames during transmission. (David Johnston, Jesse Walker, 2004)

0 Black Hat Threats to WiMAX Technology

Black Hat Threats to WiMAX Technology

Another threat to WiMax is black hat hackers, they are commonly known as awful people in our world with the negative thinking about cracking into the network or the computer system for their own financial benefit or mental satisfaction. They are also known as crackers or Black Hats. The essential thing to understand is not all the hackers are terrible as some people are doing penetration of a network or computer system in the limits of ethical standards to understand the vulnerabilities in their system or their clients system, also called white hat hackers. There are still the possibility that the WiMAX network can be a victim of black hats like WiFi and other wireless technologies.

0 Identity Theft threat to WiMAX Technology

Threat of Identity Theft In WiMAX

Another major threat to WiMax is Identity Theft; this method includes reprogramming of a device with the hardware address of another device. The address can be stolen over the air by interrupting management messages. A rogue Base Station (BS) is an attacker station which act as a genuine Base Station (BS). It confuses a set of Subscriber Stations or Mobile Stations when attempting to get service through what they believe being a genuine Base Station (BS). It is complicated in WiMax networks because of time division multiple access (TDMA) model. In this case, the attacker must transmit while the real Base Station (BS) is transmitting, with more signal strength and place the real Base Station (BS)’s signal in the background, additionally attacker has to capture the identity and wait until a time slot of genuine Base Station (BS) starts transmitting the data.

0 Key Management Problem in WiMAX Technology

Key Management Problem In WiMAX Technology

Key Management is another problem is WiMax technology, which uses Traffic Encryption Key (TEK) sequence space; it uses sequence number to make different messages. The protocol identifies each Traffic Encryption Key (TEK) with a 2 bit sequence number, enclosing the sequence number from 3 to 0 on every fourth re-key as a problem of replay attack; if replay works, Subscriber Station (SS) could not be able to detect this issue. (D Johnston, J Walker, 2004)

0 Mutual Authentication Problem In Wimax Technology

Mutual Authentication Problem in Wimax

There are two types of certificate are categorize by WiMax standard: one is for Subscriber Station (SS) certificates and the other is for manufacturer certificates but there is no provision for Base Station (BS) certificates. A manufacturer certificate identifies the manufacturer of a WiMaxdevice. It can be a self signed certificate or subjected to any third party. A Subscriber certificate identifies a particular Subscriber Station and enclosed its MAC address in the subject field. Manufacturers normally create and sign Subscriber Station certificates.

Generally the Base Station (BS) uses the manufacturer certificate’s public key to validate theSubscriber Station (SS) certificate, and therefore identify the device as genuine. This design assumes that the Subscriber Station (SS) keeps the private key related to its public key in a sealed storage, preventing attackers from easily compromise it. The major drawback of theWiMax security design is the lack of a Base Station (BS) certificate. The only approach to defend the client against forgery or replay attack is to offer a scheme for mutual authentication. In 802.16e, EAP can be verified with specific authentication methods such as X.509 certificate.(D Johnston, J Walker, 2004)

0 Privacy Sub Layer Threats to WiMAX Technology

Privacy Sub Layer Threats to Wimax Technology

Privacy Sub layer’s main objective was to protect service providers against theft of service, rather than securing network users. It is obvious that the privacy sub layer only secures data at the data link layer, but it does not ensure complete encryption of user data. Furthermore, it does not protect physical layer from being interrupted. It is essential to include technologies to secure physical layer and higher layer security for a converged routable network and devices within the system. (Derrick Boom, 2004)

0 Physical Layer Threats to WiMAX Technology

Physical Layer Threats to Wimax Technology Privacy Sub-layer resides on the top of Physical layer in IEEE 802.16 standard, therefore,Wimax networks are open to to physical layer attacks for example, blocking and rushing. Blocking is done by activating a source of strong noise to significantly lowering the capacity of the channel, therefore denying services (DoS) to all stations.

However, blocking or jamming is detectable with radio analyzer devices. Rushing or scrambling is another type of jamming, but it takes place for a short interval of time aimed at particular frames. Control or management messages could be jumbled, but it is not possible with delay sensitive message i.e., scrambling Uplink slots are comparatively hard, because attacker has to interpret control information and to send noise during a particular interval. (Michel Barbeau)

0 Data Link Layer Threats to WiMAX Technology

Data Link Layer Threats to WiMAX In a typical Wi-Fi mechanism, a digital subscriber line (DSL) feeds a packet-ized bit stream into a modem or access point, which in turn broadcasts a radio signal; often encrypted to Wi-Fi enabled clients that de-packet this data into information. In a WiMAX installation, a fixed wireless base station, similar in concept to a cell phone tower, serves an always-on radio signal directly accessible by WiMAX enabled clients, with no need for leased lines or an intermediate access point.
Like Wi-Fi, the WiMax Media Access Control (MAC) protocol, a sub layer of the data link layer, manage the consumer’s access to the physical layer. However, the scheduling algorithm within the WiMAX MAC protocol offers optimal prioritization of this traffic based on First-In First-Out (FIFO) scheduling, in which clients seeking access to the base station are allocated bandwidth upon time of initial access, instead of random queue assignment based on order of Media Access Control (MAC) address as in Wi-Fi. Furthermore, the WiMax Media Access Control (MAC)protocol ensures optimal quality of service (QoS) over its WiFi predecessor, allocating bandwidth effectively by balancing client’s needs instead of best effort service; that is, equal distribution of what remains after allocation to other consumers.
In addition, before encrypting the radio signal with Wired Equivalent Privacy (WEP), WPA/PSK, or any other existing Layer 2 security protocol, WiMax basic authentication architecture, by default, employs X.509-based public key infrastructure (PKI) certificate authorization, in which the base station authenticates the client’s digital certificate prior to granting access to the physical layer.(Michel Barbeau, 2005)

0 Application Layer Threats to WiMAX Technology- Application Layer Gateway (ALG) in Wimax Technology

Application Layer Threats to WiMAX Technology Software based threat management and secure access solutions will be as essential as ever, with a typical security infrastructure comprising components such as firewalls, virtual private networking (VPN), Internet key exchange (IKE) tunnelling, and intrusion prevention systems (IPS), each of which reside at the application layer of WiMAX Infrastructure .
For example, in an WiMax mesh network installation where routers or gateways will operate as intermediaries, or hot spots linking client and base station, there is an increased potential ofsecurity vulnerabilities, as the intermediary routers that reside between base station and client are presentable and vulnerable to attacks. Popular application level services, such as voice over Internet protocol (VoIP), could be broken by hackers who can initiate the download of remote configuration settings and resynchronize clients’ CPE settings to their specifications. Hackers may also replicate, or spoof the address of the intermediary router or server and deceive other clients into believing their connection is secure, thus opening them up to malicious attack. These routers and gateways will require robust security measures to ensure that unprotected clients remain protected behind the intermediary access point. (Lei Han, 2006)
The majority of existing routers will have their own firewall components that provide Application Layer Gateway (ALG) functionality for the signalling protocols that support and keep multiple sessions. Any deficiency in the Application Layer Gateway (ALG) functionality could result in diminished QoS for low latency applications, such as VoIP and videoconferencing. OEMs must develop devices with Application Layer Gateways (ALG)s that permit inward call requests to the devices only from the device registered with the server and endpoints, while dynamically allowing inward media packets only on call set up. These media sessions are to be disabled on termination of the connection. (Lei Han, 2006)

0 Denial of Service (DoS) Attacks to WiMAX Technology

Denial of Service (DoS) Attacks on WiMAX In wireless metropolitan area networks (MAN), the data service for a mobile is based on the model of service flow, a MAC layer transport service that describes the unidirectional flow of either uplink or downlink data. The establishment of a service flow uses a two phase model: a service flow is first admitted with provisioned resources, and then the service flow is then activated to have the resources committed on an on-demand basis. The service flow may be de-activated later to conserve network resources.

Primarily, when a wimax network has no downlink or uplink data, it will enter either Sleep Mode or Idle Mode, both of which aim to trim down the power utilization of the mobile station. Upon the availability of data, the serving base station will awaken the mobile station. The mobile station then establishes a connection with the base station via initial ranging. Ranging parameters are then adjusted for the connection. Finally, the service flow is reactivated for data transfer, and the mobile station returns to the normal operation stage. Depending on whether the serving base station has the necessary information, the mobile station may need to carry out more signaling operations, such as basic capability negotiation, authentication and key management, re-registration, as well as IP connectivity reestablishment. Given the above signaling procedures, attackers may also launch similar signaling attacks to WiMax base station by triggering unnecessary state transitions that overload the base station with signal processing that leads to denail of service (DoS) attacks.. (Ramana Mylavarapu, 2005)

0 Rouge Base Station threat to WiMAX network

Rouge Base Station A rogue base station is an attacker station that duplicates a legitimate base station. The rogue base station puzzles a set of subscribers trying to get service through what they believe to be a legitimate base station. It may result in long disturbance of service. The exact method of attack depends on the type of network. In a WiFi network, which is carrier sense multiple access, the attacker has to capture the identity of a legitimate access point. Then it builds frames using the legitimate access point's identity. It then injects the crafted messages when the medium is available. In a WiMax network, this is more difficult to do because WiMax uses time division multiple access. The attacker must transmit while the rogue base station is transmitting.

The signal of the attacker, however, must arrive at targeted receiver subscribers with more strength and must put the signal of the rogue base station in the background, relatively speaking. Again, the attacker has to capture the identity of a legitimate base station. Then it builds messages using the stolen identity. The attacker has to wait until time slots allocated to the fake base station start and transmit during these time slots. The attacker must transmit while achieving a receive signal strength higher than the one of the fake base station. The receiver subscribers reduce their gain and decode the signal of the attacker instead of the one from the fake base station. The rogue base station is likely to occur as there are no technical difficulties to resolve. Extensible Authentication Protocol (EAP) supports mutual authentication, i.e. the base station also authenticates itself to the subscriber. When EAP mutual authentication is used, the likelihood of the threat is mitigated, but not totally and remains possible for reasons similar to EAP based authorization. The rogue base station or access point attack is therefore a threat for which the risk is critical. (Wimax Vision, 2006)

0 Threats to Wimax Technology

Threats to Wimax Technology Most of the experts and professionals claiming that broadband data delivered over 3G cellular networks will choke the hope of the Wimax industry for the standard to become worldwide significant. There are too many factors involved in weakening Wimax security, stability, Quality of service etc. In this chapter I am going to discuss the threats involved in Wimax deployment and in the infrastructure after that.   A Wimax wireless access network consists of wimax base stations and wimax Customer Premise Equipments. The wimax base stations provide network add-on to the wimax CPEs. As a serving wimax base station, a wimax Customer Premise Equipment (wimax CPE) selects the one which offers the strongest signal. At this point, the subscriber plays the role of the user while a wimax base station and a collection of served wimax Customer Premise Equipments (wimax CPE's) play the role of system. The Medium Access Control (MAC) layer and physical layer are two most important layers of protocol architecture of Wimax Technology. Common Part sub layer is the essential part of Wimax technology layered architecture. In this layer, MAC Protocol Data Units (PDUs) are constructed, connections are established and bandwidth is managed. The Common Part (CP) exchanges MACService Data Units (SDUs) with the Convergence layer. The Privacy sub layer is tightly integrated with Common Part. The Privacy sub layer addresses authentication, establishment of keys and encryption. The Security sub layer exchanges MAC PDUs with the Physical layer. The Convergence layer adapts units of data of higher level protocols to the MAC SDU format, and vice versa. The Convergence layer also sorts the incoming MAC SDUs by the connections to which they belong. The Physical layer is a two-way mapping between MAC PDUs and Physical layer frames received and transmitted through coding and modulation of radio frequency signals. (Michel Barbeau, 2005)

0 RADIUS (Remote Access Dial in User Service) in Wimax Technology

Remote Access Dial in User Service (RADIUS) The most widely used standard for communication between the authenticator and the authentication server, Remote Access Dial In User Service (RADIUS), is an IETF standard that defines the functions of the authentication server and the protocols to access those functions.Remote Access Dial In User Service (RADIUS) is a client/server User Datagram Protocol (UDP) application that runs over IP.
The authentication server is the Remote Access Dial In User Service (RADIUS) server, and the authenticator is the Remote Access Dial In User Service (RADIUS) client. In addition to authentication, Remote Access Dial In User Service (RADIUS) supports authorization and accounting functions, such as measuring session volume and duration that can be used for charging and billing purposes. The authentication, authorization, and accounting functions are collectively referred to as AAA functions. Numerous extensions to Remote Access Dial In User Service (RADIUS) have been defined to accommodate a variety of needs, including supporting EAP. (Wimax Forum, 2007)
Remote Access Dial In User Service (RADIUS), however, does have a number of deficiencies that cannot be easily overcome by modifications. Recognizing this, the IETF has developed a new standard for AAA functions: DIAMETER. Although not backward compatible with Remote Access Dial In User Service (RADIUS), DIAMETER does provide an upgrade path to it. DIAMETER has greater reliability, security, and roaming support than Remote Access Dial In User Service(RADIUS) does. (Wimax Forum, 2007)

0 WiMAX Authentication Access Control, Wimax EAP (Extensible Authentication Protocol)

Access control in wimax technology is the security mechanism to ensure that only valid users are allowed access to the wimax network. In the most general terms, an access control system has three elements:   1. An entity that desires to get access: the supplicant. 2. An entity that controls the access gate: the authenticator. 3. An entity that decides whether the supplicant should be admitted: the authentication server.
A typical access control architecture used by service providers. Access control systems were first developed for use with dial-up modems and were then adapted for broadband services. The basic protocols developed for dial-up services were PPP (point-to-point protocol) and Remote Dial-In User Service (RADIUS). PPP is used between the supplicant and the authenticator, which in most cases is the edge router or Network Access Server (NAS), and RADIUS is used between the authenticator and the authentication server. (Michel Barbeau) PPP originally supported only two types of authentication schemes: Password authentication protocol (PAP) and Challenge Handshake Authentication Protocol (CHAP), both of which are not strong enough to be used in wireless systems. More safer authentication schemes can be supported by PPP using Extensible Authentication Protocol (EAP). (Michel Barbeau)
Extensible Authentication Protocol Entensible Authentication Protocol (EAP), a flexible framework created by the IETF (RFC 3748), allows arbitrary and complicated authentication protocols to be exchanged between the supplicant and the authentication server. Entensible Authentication Protocol (EAP) is a simple encapsulation that can run over not only PPP but also any link, including the WiMAX link. Entensible Authentication Protocol (EAP) includes a set of negotiating messages that are exchanged between the client and the authentication server. The protocol defines a set of request and response messages, where the authenticator sends requests to the authentication server; based on the responses, access to the client may be granted or denied. The protocol assigns type codes to various authentication methods and delegates the task of proving user or device identity to an auxiliary protocol, an Entensible Authentication Protocol (EAP) method, which defines the rules for authenticating a user or a device. A number of Entensible Authentication Protocol(EAP) methods have already been defined to support authentication, using a variety of credentials, such as passwords, certificates, tokens, and smart cards. For example, Protected Entensible Authentication Protocol (PEAP) defines a password- based EAP method, EAP-transport-layer security (EAP-TLS) defines a certificate-based Entensible Authentication Protocol (EAP) method, and EAP-SIM (subscriber identity module) defines a SIM card–based EAP method. EAP-TLS provides strong mutual authentication, since it relies on certificates on both the network and the subscriber terminal. (Chong li, 2006). In WiMAX systems, Entensible Authentication Protocol (EAP) runs from the mobile station to the base station over the Privacy Key Management version 2 (PKMv2) security protocol defined in the IEEE 802.16e-2005 air-interface. If the authenticator is not in the base station, the base station relays the authentication protocol to the authenticator in the access service network (ASN). From the authenticator to the authentication server, Entensible Authentication Protocol (EAP) is carried over RADIUS.

1 PKI - Public Key Infrastructure In Wimax

PKI - Public Key Infrastructure In Wimax With symmetric key encryption, both the transmitter and the receiver need to use the same key, which raises the question of how the key itself can be securely transmitted. One way to do this is to set up the shared secret key a priori via an out-of-band method. For example, a shared secret password could be hard-coded into both the transmitter and the receiver; on the other hand, a service provider could give the key to a subscriber at the time of signing up for service. This approach, however, does not scale very well for extensive use. For example, it becomes impossible to generate millions of individual unique keys and deliver them to each person. Also, relying on out-of-band mechanisms is unmanageable, prone to errors, and often not very practical.
Asymmetric key encryption is an elegant solution to the key-distribution problem. Asymmetric key encryption uses two keys: a public key and a private key. When a ciphertext is encrypted using one of the two keys, it can be decrypted only by the other key. Both the keys are generated simultaneously using the same algorithm RSA and the public key is disclosed widely and the private key is kept secret. The Wimax Public Key Infrastructure (PKI), which is widely used to secure a variety of Internet transactions, is built on this idea of using asymmetric keys. (Arkoudi-Vafea Aikaterini, 2006)
Authentication in Public Key Infrastructure (PKI) Here, we need a mechanism to ensure that a given user or device is as stated. For example, to ensure that the data received is really from user B, user A can use the process using public and private keys, along with a random number. If B returns A’s random number, A can be assured that the message was sent by B and no one else. Similarly, B can be assured that A received the message correctly. The message could not have been read by anyone else and could not have been generated by anyone else, since no other user has the private key or the correct random number. Shared Key Distribution in Public Key Infrastructure (PKI) To securely send data to user B, user A can do so by using the public key of user B to encrypt the data. Since it now can be decrypted only by the private key of user B, the transaction is secured from everyone else. This secure transaction can now be used to distribute a shared secret key, which can then be used to encrypt the rest of the communication, using a symmetric key algorithm, such as AES it also shows how, after mutual authentication, a shared key is established for encrypting the rest of the session. (Eduardo B. Fernandez, Michael VanHilst and Juan C. Pelaez) Non-Repudiation & Message Integrity in Public Key Infrastructure (PKI) Asymmetric keys and Wimax Public Key Infrastructure (PKI) can also be used to prove that someone said something. This non-repudiationis the role often played by signatures on a standard letter. In order to establish non-repudiation, it is not necessary to encrypt the entire text, which is sometimes computationally expensive and unnecessary. An easier way to guarantee that the text came from the sender and has not been tampered with is to create a message digest from the message and then encrypt the digest, using the private key of the sender. A message digestis a short fixed-length string that can be generated from an arbitrarily long message. It is very unlikely that two different messages generate the same digest, especially when at least 128-bit message digests are used. Message Digest 5 algorithm (MD-5) and Secure Hash Algorithm (SHA) are two algorithms used for computing message digests, both of which are much faster and easier to implement than encryption. By sending the unencrypted text along with an encrypted digest, it is possible to establish non-repudiation and message integrity. (Eduardo B. Fernandez, Michael VanHilst and Juan C. Pelaez) Digital Certificates Public Key Infrastructure (PKI) Digital certificates are a means of certifying the validity and validity of public keys. As part of theWimax Public Key Infrastructure (PKI), a certification authority, which essentially is a trusted independent organization, such as VeriSign, certifies a set of public and private keys for use withWimax Public Key Infrastructure (PKI) transactions. The certification authority issues digital certificates that contain the user’s name, the expiry date, and the public key. This certificate itself is digitally signed by the certification authority using its private key. The public key of Certification Authorities are widely distributed and known; for example, every browser knows them. In the context of broadband wireless services, subscriber terminals may be issued individual digital certificates that are hard coded into the device, and can be used for device authentication.(Sonnenreich Wes, Albanese Jason, 2003)

0 Encryption: Advanced Encryption Standard (AES) in WiMAX

Advanced Encryption Standard (AES) in WiMAX Advanced Encryption Standard (AES) is the new data encryption standard adopted by the National Institute of Standards as part of Federal Information Processing Standard (FIPS) and is specified as a link-layer encryption method to be used in WiMAX Technology. Advanced Encryption Standard (AES) is based on the Rijndael algorithm, which is a block ciphering method believed to have strong cryptographic properties. Besides offering strong encryption, Advanced Encryption Standard (AES) is fast, easy to implement in hardware or software, and requires less memory than do other comparable encryption schemes. The computational efficiency of Advanced Encryption Standard (AES) has been a key reason for its rapid widespread adoption. The Advanced Encryption Standard (AES) algorithm operates on a 128-bit block size of data, organized in a 4 x 4 array of bytes called a state. The encryption key sizes could be 128, 192, or 256 bits long; WiMAX Technology specifies the use of 128-bit keys.

In order to use a block cipher, such as Advanced Encryption Standard (AES), a reversible mechanism is needed to convert an arbitrary length message into a sequence of fixed-size blocks prior to encryption. The method to convert between messages and blocks is referred to as the cipher’s mode of operation, several of which are proposed for Advanced Encryption Standard (AES). The mode of operation needs to be carefully chosen so that is does not create any security holes and with implementation considerations in mind. The mode used in WiMAX Technology is called the counter mode. In counter mode, instead of directly encrypting the plain text, an arbitrary block, called the counter, is encrypted using the Advanced Encryption Standard (AES) algorithm, and the results are XORed with the plain text to produce the ciphertext. The arbitrary block is called the counter because it is generally incremented by 1 for each successive block processed ciphertext is never the same for two identical inputs, thereby providing protection from an onlooker observing patterns of repetition in the ciphertext. (Arkoudi-Vafea Aikaterini, 2006)

0 Encryption In WiMAX Technology

Encryption In WiMAX Technology Encryption is the method used to protect the confidentiality of data flowing between a transmitter and a receiver. Encryption in WiMAX Technology involves taking a stream or block of data to be protected, called plain text, and using another stream or block of data, called the encryption key, to perform a reversible mathematical operation to generate a ciphertext. The ciphertext is unintelligible and hence can be sent across the network without fear of being eavesdropped.

The receiver does an operation called decryption to extract the plaintext from the ciphertext, using the same or different key. When the same key is used for wimax encryption and decryption, the process is called symmetric key encryption. This key is typically derived from a shared secret between the transmitter and the receiver and for strong encryption typically should be at least 64 bytes long. When different keys are used for encryption and decryption, the process is called asymmetric key encryption. Both symmetric and asymmetric key encryptions are typically used in broadband wireless communication systems, each serving different needs.

0 Wimax PKM in WiMAX Technology

PKM (Privacy Key Management) Protocol in WiMAX Technology Wimax CPE (Customer Premise Equipment) make use of the Privacy Key Management (PKM) Protocol to gain authorization and traffic keying material from the Wimax Base Station (BS), and to maintain periodic reauthorization and key refresh. The Privacy Key Management (PKM) protocol uses X.509 digital certificates, and two-key triple Data Encryption Standard (DES) to secure key exchanges between a given Wimax CPE (Customer Premise Equipment) andWimax Base Station (BS), following the client-server model. Here, the Wimax CPE (Customer Premise Equipment) as the client requests keying material while the Wimax Base Station (BS) as the server act in response to those requests, ensuring individual Wimax CPE (Customer Premise Equipment) clients receive only the keying material for which they are authorized. The Privacy Key Management (PKM) Protocol first creates an Authorization Key (AK), which is a secret symmetric key shared between the Wimax CPE (Customer Premise Equipment) and BS. The AK is then used to protect subsequent Privacy Key Management (PKM) Protocol exchanges of Traffic Encryption Keys (TEK). The use of the AK and a symmetric key cryptosystem reduces the overhead due to the computationally expensive public key functions. (Sen Xu, Chin-Tser Huang)

Wimax Base Station (BS) authenticates a Wimax CPE (Customer Premise Equipment) during the primary authorization exchange. The Wimax CPE (Customer Premise Equipment) device certificate would enclose the RSA public key and other device specific information, such as its MAC address, serial number, and manufacturer ID. Within the authorization exchange, the Wimax CPE (Customer Premise Equipment) would then send a copy of this device certificate to the Wimax Base Station (BS). The Wimax Base Station (BS) must then authenticate the syntax and information in the Wimax CPE (Customer Premise Equipment) certificate, and possibly carry out certificate path validation checks. If properly verified, the Wimax Base Station (BS) as part of its replies to the Wimax CPE (Customer Premise Equipment) would encrypt the Authorization Key (AK) using the public key of the Wimax CPE (Customer Premise Equipment) that could be found within the received certificate from the Subscriber station. Since only the Wimax CPE (Customer Premise Equipment) device contains the matching private key, only the Wimax CPE (Customer Premise Equipment) device can de-crypt the message and obtain the AK assigned to it. (Sen Xu, Chin-Tser Huang)

1 Network Access & Initialization in WiMAX Technology

Network Access and Initialization in Wimax In this section I am going to explain briefly at the activities of a subscriber station in the framework of gaining network access and initialization. The PKM Protocol is used during the network access and initialization phase, in the authentication and authorization steps. A WiMAX Customer Premise Equipment (CPE) must perform a number of tasks before gaining access to a wimax network. These tasks are discussed in detail below.
Scanning and Synchronization in Wimax technology First the WiMAX Customer Premise Equipment (CPE) searches for a downlink signal from theWiMAX Base Station (BS) and try to coordinate with it. If previous downlink channel existed, the WiMAX Customer Premise Equipment (CPE) will try reusing those functional parameters. If not, the WiMAX Customer Premise Equipment (CPE) must look into all the potential channels in the downlink frequency band. When a channel has been selected, the WiMAX Customer Premise Equipment (CPE) attempts to synchronize with the downlink transmission by detecting the cyclic frame preambles. (David Johnston, Hassan Yaghoobi, 2004)
Uplink & Downlink Parameters Detection After synchronization has been established at the physical layer, the Subscriber Station (SS) then continues to search for the Downlink Channel Descriptor (DCD) and the Uplink Channel Descriptor (UCD) messages that are regularly broadcasted by the WiMAX Base Station (BS). The Downlink Channel Descriptor (DCD) and Uplink Channel Descriptor (UCD) messages hold information regarding the physical layer features of both the downlink and uplink channels. Among others, these messages then permit theWiMAX Customer Premise Equipment (CPE) to learn about the modulation type and Forward Error Correction (FEC) method of the carrier. Depending on the PHY specification selected for a given settings, the BS also frequently transmits uplink-map (UL-MAP) and downlink-map (DL-MAP) messages that describe their burst start times. It is through the DL-MAP and UL-MAP messages that the WiMAX Base Station (BS) can assign access to the individual channels. (Shyam Parekh, 2006) Ranging & Subscriber Station Capabilities in Wimax Technology In this stage, the WiMAX Customer Premise Equipment (CPE) performs ranging, which is the process of aligning the WiMAX Customer Premise Equipment (CPE) transmission timing-wise to the start of a slot during contention for access. This process is part of framing and media access in 802.16 and consists of initial ranging and periodic ranging. The early ranging contention slot is used for network entry. Here, the WiMAX Customer Premise Equipment (CPE) sends a ranging request packet (RNG-REQ) in the primary ranging contention slot. If this message is received correctly by the WiMAX Base Station (BS), it then replies to the WiMAX Customer Premise Equipment (CPE) with a ranging response packet (RNG-RSP) unfolding the timing and power correction information to the WiMAX Customer Premise Equipment (CPE). This permits the WiMAX Customer Premise Equipment (CPE) to adjust the timing and power of its signal as received by the WiMAX Base Station (BS). The response will also tell the WiMAX Customer Premise Equipment (CPE) about the connection IDs (CID) chosen by the WiMAX Base Station (BS). The other type of ranging, namely, periodic ranging, provides chances for WiMAX Customer Premise Equipment (CPE) to send ranging-request messages to the WiMAX Base Station (BS) in order to adjust power levels, time, and frequency offsets. (Derrick Boom, 2004) After ranging is completed, the WiMAX Customer Premise Equipment (CPE) reports its physical layer capabilities to the WiMAX Base Station (BS). This consists of the modulation and coding schemes holds by the WiMAX Customer Premise Equipment (CPE), and whether the WiMAX Customer Premise Equipment (CPE) within the WiMAX Frequency Division Duplexing (FDD) supports half-duplex or full-duplex. The WiMAX Base Station (BS) has the choice of accepting or rejecting these capabilities of the WiMAX Customer Premise Equipment (CPE). (Derrick Boom, 2004) Subscriber Station Authentication in Wimax, Authorization & Registration During subscriber station authentication in wimax, the WiMAX Customer Premise Equipment (CPE) must be authenticated by the WiMAX Base Station (BS) and obtain authorization from the WiMAX Base Station (BS) by using the PKM Protocol. Each WiMAX Customer Premise Equipment (CPE) device is assigned to an X.509 digital certificate, which is physically bound to the device hardware during manufacturing. One achievable implementation is to include the devices MAC-address in its certificate. The MAC address in WiMAX is the usual 48bit address used in other IEEE 802 standards such as Ethernet. It is essential to note that just as in Data Over Cable Service Interface Specifications (DOCSIS) compliant cable modem devices, the digital certificate and the private key are allocated during manufacturing of the WiMAX Customer Premise Equipment (CPE) device. The private key must be embedded in the hardware in such a way that it is complicated or infeasible for the user to access or extract. (Michaela Greiler, 2007) After verification of authentication and authorization, the WiMAX Customer Premise Equipment (CPE) continues with the registration stage. Here, the WiMAX Customer Premise Equipment (CPE) sends a registration request message to the WiMAX Base Station (BS), who answers with a registration response message including among others a secondary management connection ID for the WiMAX Customer Premise Equipment (CPE) and the IP version used for the secondary management connection. The appearance of the registration response message from the WiMAX Base Station (BS) tells to the WiMAX Customer Premise Equipment (CPE) that it has been registered in the network and therefore allowed to enter the network. (Michaela Greiler, 2007) IP Connectivity in Wimax Technology At the completion of registration, the WiMAX Customer Premise Equipment (CPE) can now obtain an IP address through the DHCP protocol, obtain current time information (e. g., through the Internet Time Protocol), and also obtain other parameters from the WiMAX Base Station (BS).(Michaela Greiler, 2007)

0 WiMAX Security

Security in WiMAX Technology Security is a broad and complex subject, and this section provides only a brief introduction to it. I am going to cover the basic security issues, introduce some terminology, and provide a brief overview of some of the security mechanism of Wimax Technology.
Well designed security architecture for a Wimax and other wireless communication networks should support the following essential requirements: Privacy: Provide protection from eavesdropping as the user data traverses the network from source to destination. Data integrity: Ensure that user data and control/management messages are protected from being tampered with while in transit. Authentication: Have a mechanism to ensure that a given user/device is the    one it claims to be. Conversely, the user/device should also be able to verify the authenticity of the network that it is connecting to. Together, the two are referred to as mutual authentication. Authorization: Have a mechanism in place to verify that a given user is authorized to receive a particular service. Access control: Ensure that only authorized users are allowed to get access to the offered services.
Wimax security is typically handled at multiple layers within a system. Each layer handles different aspects of security, though in some cases, there may be redundant mechanisms. As a general principle of security, it is considered good to have more than one mechanism providing protection so that security is not compromised in case one of the mechanisms is broken. At the link layer, strong encryption should be used for wireless systems to prevent over-the-air eavesdropping. Also needed at the link layer is access control to prevent unauthorized users from using network resources: precious over-the-air resources. (Chong Li, 2006) Link layer encryptions are not often used in wired links, where eavesdropping is considered more difficult to do. In those cases, privacy is ensured by the comprehensive security mechanisms used at the higher layers. At the network layer, a number of methods provide security. The network itself may be protected from malicious attack through the use of firewalls. Authentication and authorization services are typically done through the use of Authentication, Authorization, and Accounting (AAA) protocols, such as RADIUS (Remote Access Dial-In User Service).. At the transport layer, TLS its precedent was called Secure Sockets layer (SSL) may be used to add security to transport layer protocols and packets. At the application layer, digital signatures, certificates, digital rights management, and so on are implemented, depending on the sensitivity of the application. (Arkoudi-Vafea Aikaterini, 2006)

0 WiMAX Security Functions

WiMAX Security Functions Unlike Wi-Fi, Wimax technology system were designed at the beginning with robust security in mind. The standard includes state of the art methods for ensuring user data privacy and preventing unauthorized access, with additional protocol optimization for mobility. Security is handheld by aprivacy sub layer within the WiMax Medium Access Control (MAC). The key aspects of Wimax security are as follows;
Support for Privacy User data is encrypted using cryptographic schemes of proven robustness to provide privacy. BothAdvanced Encryption standard (AES) and Triple data Encryption Standard (3DES) are supported. Most system implementation will liely uses Advanced Encryption standard (AES), as it is the new encryption standard approved as compliant with Federal Information Processing Standard (FIPS) and is easier to implement. The 128-bit or 256-bit key used for deriving the cipher is generated during the authentication phase and is periodically refreshed for additional protection.(Jamshed Hasan)
Authentication in Wimax Technology WiMAX offers a flexible means for authenticating subscriber stations and users to prevent from unauthorized use. The authentication structure is based on the Internet Engineering Task Force (IETF) EAP, which supports a variety of identifications, suchs as username/password, digital certificates, and smart cards. WiMAX terminal devices come with built-in X.509 digital certificates that contain their public key and MAC address. WiMAX operators can apply the certificates for device authentication and use a username/password or smart card authentication on top of it for authentication of users. (Sanida Omerovic) Flexible Key Management Protocol in Wimax The Privacy and Key Management Protocol Version 2 (PKMv2) is used for transmitting keying material securely from the base station to the mobile station. PKM protocol are also used to periodically reauthorize and refreshing the keys. PKM protocol is a client-server protocol: The mobile station acts as the client; the base station, the server. PKM protocol uses X.509 digital certificates and RSA (Rivest Shamer Adleman) public-key encryption algorithms to securely perform key exchanges between the base station and the mobile station. (David Johnston & Jesse Walker, 2004) Protection of Control Messages in Wimax The integrity of over the air control messages is protected by using message digest schemes, such as Advance Encryption Standard (AES) based Cipher-based Message Authentication Code (CMAS) or Message Digest 5 based HMAC (Hash-based Message Authentication). (Jamshed Hasan) Support for Fast Handover in Wimax To support fast handovers, WiMAX technology allows the mobile station to use pre-authentication with a particular target base station to assist accelerated re-entry. A three-way handshake scheme is supported to optimize the re-authentication mechanisms for supporting fast handovers, while at the same time preventing any man-in-the-middle attacks. (David Johnston & Jesse Walker, 2004)

0 Security of Wimax Technology

WiMAX Security Wireless systems always make some people worried when speaking of security. After all, every wireless system broadcasts, by definition, everything you’re doing on the network to the world or at least the part of the world within range. Security is an important consideration in any communication system design but is particularly so in wireless communication systems. The fact that connection can be established in a loosen fashion makes it easier to intrude in an ordinary and undetectable manner than is the case for wired access. Further, the shared wireless medium is often perceived by the general public to be somewhat less secure than its wired counterpart. Therefore, a robust level of security must be built into the design of wireless systems.
From the point of view of an end user, the primary wimax security concerns are privacy and data integrity. Users need assurance that no one can eavesdrop on their sessions and that the data sent across the communication link is not tampered. This is usually achieved through the use ofwimax network encryption. I am going to discuss the encryption in the next chapter in detail.
From the service provider’s point of view, an important wimax security consideration is preventing unauthorized use of the network services. This is usually done using strong authentication and access control methods. Authentication and access control can be implemented at various levels of the network such as the physical layer, and the privacy sub layer. The service provider’s need to prevent fraud should be balanced against the inconvenience that it may impose on the user.

0 Wimax Deployments: Deployments of Wimax Technology Networks around the globe

Wimax Deployments Wimax Technology is a great development in wireless technology offering long distance broadband access. After viewing the rapid growth of Wimax technology in large business companies, multimedia project software and hardware manufacturer start to develop and test the compulsory components to deploy a Wimax Technology network. Large business corporations such as Intel, Samsung, Motorola and others have commenced worldwide deployment.
In 2004  leapfrogging cables and DSl technologies used to fetch wireless broadband access to rural areas and in 2009 Wimax technology widely spread in all over the world. Fixed wimax technology introduced in 2008. The rapid development of both Wimax technologies will be rolling out in coming days. For Wimax deployments; Asia and Amrica working as a testing ground because in Taiwan, Pakistan, South Africa, Vietnam, and Nigeria Wimax technology take start and now the growth or accomplishment of Wimax deployments covering whole world. At the moment Wateen Technologies deployed Wimax Network in Pakistan that is one of the largest Wimax network in the world. In united state Sprint, clearwire and Nextel communications have already bought up the available spectrum and Wimax wireless technologies has been start in many urban and metropolitan areas. It is more expected that Wimax Technology will take over the mobile industries. The Wimax deployment skill set to overcome the digital divide because of easiness and efficiency. The Wimax deployments going on today throughout the world are under as.
Wimax Deployments in Lao Cai, Vietnam Lao Cai is a maintained area located on Chinese border in Vietnam. It has round about 600,000 populations been most community is very poor. Intel, USAID, and VDC get on partnership to bring broadband and VoIP services via Wimax technology in region in 2004. The objective behind this partnership is that to encourage overseas investment and promote economic development in a region. Than Lao Cai had attractive good mobile phone exposure in the region. The wimax network contains a single base station bound to provide internet access via a fiber optical backhaul.Wimax deployment is offering services in the city and nearby areas. In urban areas VoIP services would also be put in practice which offering telecommunication services specially when there is never had a phone. In the Wimax deployment there is a base station which has an antenna that installed up to 70 meters on a telecommunications tower. In Internet café, government offices, schools, health centers, and farm about 20 modem installed and sip phone provided to each site. Then within local PSTN a line up VoIP switch and gateway connected which are located 300 miles away. Now the community of Lao Cai makes progress   with broadband and telecommunication transportation. Nowadays Intel which is a leader to introduce this technology is thinking to implement Wimax deployment in nearby areas to get better economical status and for this it providing satellite backhaul for VoIP and broadband access. Wimax Deployments in Gauteng, South Africa The deployment of Wimax technology is beginning in Gauteng which is the province of South Africa. Gauteng is a large industrial region and Pretoria and Johannesburg are its popular cities. Almost in 150 countries Wimax deployment has been established and a WiMAX business market share of over 60% within 3.5 GHZ frequency range. Wimax broadband access is offering multimedia internet, Voice and data services. According to a report internet carry on to achieve approval in South Africa. This has socio-economic implication that goes ahead of the ideological or moral with very real insinuation for the development of the Internet economy in South Africa. The deployment of WiMAX technology is an inexpensively practicable means to recommend equivalent access for all. Wimax Deployments in the United States Clearwire and Sprint Nextel have been buying up Wimax spectrum in the united states. They both creating a large metropolitan market and offering 2.5 GHz frequency to 30 million users at the end of 2010. Sprint also choose the Wimax format for 4G network and Nokia, Samsung, Intel and Motorola may be excepted partner in wireless broadband scheme. The subscriber base of Clearwire is round about 200,000 and now focusing on the urban market because in rural areas there are no broadband internet services. Clearwire is playing a major role to promote Wimax Technology market and be expecting to be capable to roll out their networks more rapidly. According to a 4G research report almost 600 Wimax deployments are now alive by the end of 2009. Therefore Wimax deployment may exceed HSPA deployment because by HSPA and LTE. There are only 300 cellular networks are alive and only 70 operators have committed with them for the deployment of Wimax technology. The rapid growth of Wimax is due to wide range of coverage not only in specific areas but also in urban or rural areas. In 2011 it is expected that Wimax deployment will increase more vastly than before because of its significant features.

0 Wimax Technology Prodcuts - Equipments - Hardware

Wimax Equipments Wimax Equipments are not well known because there are very limited subscriber demands forWimax Products and equipments. Most Wimax equipments are installed with Wimax Technology chip which are certified by Wimax forum. Wimax forum is leading the way in support and setting standards in WiMAX technology and its deployment. There are many wimax products and equipments available in market with limitations. The necessary equipments required for Wimax Technology consist of Wimax base stations, Wimax receiver, Wimax antenna, and Wimax backhaul.
WiMAX Base Station Wimax base station consists of indoor Wimax equipments and a wimax tower. The common range of Wimax base station is up to 10km radius, while a base station can cover 50km or 30miles but in practice it is 10km and 6 miles only .Any node inside the coverage area would be capable to access the internet. Wimax base station work as a media access control layer and allocate uploading and downloading bandwidth according to the subscriber requirements. WiMAX receiver  The Wimax receiver is a stand alone box or PCMCIA cards which is located in your computer or laptop. It is also called customer promise equipments.
WiMAX Antenna Wimax antenna is also a standalone box and sits in your laptop or computer .Wimax antenna is just like a WiFi network but the coverage area of wimax is much larger than WiFi wireless network. Wimax antenna used to get better the signal strength of wimax user from base station. The Wimax’s external antenna mostly required in dense areas and high, mountain areas. Wimax antenna connected with the indoor unit via wire to make stronger signals. Wimax Backhaul Wimax backhaul is in fact a link system from the access point. It is used to connect system to the backbone. You can connect numerous base stations with one another with the high speed backhaul microwave links. A backhaul allow Wimax user for roaming from one base station to another base station just like a cellular phone. Wimax Future Products & Equipments There are many other products which are significant in common use for general community such as Wimax cards used for desktop and laptops computers within an installed microchip. Wimax products are under testing procedure therefore very uncommon in market. No doubt in coming days Wimax deployment takes over the older technologies through Wimax product.

0 Types of Wimax Technology

Types of WiMAX Technology (802.16) The Wimax family of standards (802.16) concentrate on two types of usage models a fixed wimax usage model and a mobile wimax usage model. The basic element that differentiates these systems is the ground speed at which the systems are designed to manage. Based on mobility, wireless access systems are designed to operate on the move without any disruption of service; wireless access can be divided into three classes; stationary, pedestrian and vehicular.
A mobile wimax network access system is one that can address the vehicular class, whereas the fixed wimax serves the stationary and pedestrian classes. This raises a question about the nomadic wireless access system, which is referred to as a system that works as a fixed wimax network access system but can change its location.
Fixed Wimax Broadband service and consumer usage of fixed Wimax access is expected to reflect that of fixed wire-line service, with many of the standards-based requirements being confined to the air interface. Because communications takes place via wireless links from wimax Customer Premise Equipment (wimax CPE) to a remote Non Line-of-sight (NLOS) wimax base station, requirements for link security are greater than those needed for a wireless service. The security mechanisms within the IEEE 802.16 standards are sufficient for fixed wimax access service. Another challenge for the fixed wiimax access air interface is the need to set up high performance radio links capable of data rates comparable to wired broadband service, using equipment that can be self installed indoors by users, as is the case for Digital Subscriber Line (DSL) and cable modems. IEEE 802.16 standards provide advanced physical (PHY) layer techniques to achieve link margins capable of supporting high throughput in NLOS environments.(Tom Carpenter, 2006) Mobile Wimax The 802.16a extension, refined in January 2003, uses a lower frequency of 2 to 11 GHz, enabling NLOS connections. The latest 802.16e task group is capitalizing on the new capabilities this provides by working on developing a specification to enable mobile Wimax clients. These clients will be able to hand off between Wimax base stations, enabling users to roam between service areas. Wimax backhaul Wimax backhaul is actually a connection system from the Access Point (AP) back to the provider and to the connection from the provider to the network. A wimax backhaul can set out any technology and media provided; it connects the system to the backbone. In most of the Wimax deployments circumstances, it is also possible to connect several wimax base stations with one another by use of high speed wimax backhaul microware links. This would also allow for roaming by a Wimax subscriber from one wimax base station coverage area to another, similar to roaming enabled by cellular phone companies. (Xiaole Song, 2007) There can be two cases of portability; full mobility or limited mobility. The effortless case of portable service involves a user transporting a Wimax modem to a different location. Provided this visited location is serve by wireless broadband service, in this scenario the user re-authenticates and manually re-establishes new IP connections and is afforded broadband service at the visited location. (Tom Carpenter, 2006) In the fully mobile scenario, user expectations for connectivity are comparable to facilities available in third generation (3G) voice/data systems. Users may move around while engaged in a broadband data access or multimedia streaming session. Mobile wireless systems need to be robust against rapid channel variation to support vehicular speeds. There are significant implications of mobility on the IP layer owing to the need to maintain rout-ability of the host IP address to preserve in-flight packets during IP handoff. This may require authentication and handoffs for uplink and downlink IP packets and Medium Access Control (MAC) frames. The need to support low latency and low packet loss handovers of data streams as users transition from one base station to another is clearly a challenging task. For mobile data services, users will not easily adapt their service expectations because of environmental limitations that are technically but not directly relevant to the mode of user. For these reasons, the network and air interface must be designed to anticipate these user expectations and deliver accordingly. (Deepak Pareek, 2006)