Wireless Security

In this tutorial, you will learn the basic concepts of wireless security. After reading this tutorial, you will learn the importance of wireless security, 802.11 security, WPA and WPA2, session keys, and Bluetooth security.

Contents:

1. What is Wireless Security?
2. Importance of Wireless Security
3. 802.11 Security
4. WPA and WPA2
5. Session Key
6. Bluetooth Security

What is Wireless Security?

Wireless security refers to the protection of wireless networks, devices, and data from unauthorized access, attacks, and vulnerabilities. It involves implementing measures such as encryption, authentication, access control, and network segmentation to ensure the confidentiality, integrity, and availability of wireless communications and data.

Importance of Wireless Security

In wireless networks, radio waves are used for communication, so confidential information is more likely to leak from the network. VPNs and firewalls can provide security to the network, but if the wireless network is used for transmission with radio waves, there can be a possibility of information leaking. Therefore, we must also provide wireless security to achieve confidentiality, integrity, and authentication of the data.

• Normally, 802.11 networks have a range of a few hundred meters, so it is easy for an attacker to spy on the network.
• Manufacturers have created wireless base stations that make access points user-friendly. If a non-technical person can easily configure an access point from one point to another then it is easy for hackers to access it as there is no security.
• When a user plugs the access point into an electrical power socket, the access point begins to operate immediately without any protection. Therefore, there is a problem of information leakage in the radio range.
• To solve the above problems, we need wireless security because security is even more important in wireless networks than wired networks.
• Providing wireless security requires authentication and encryption.

802.11 Security

When a device transmits data to another device, encryption must be done to protect the data from malicious attacks.

The figure below explains the wireless network security scenario.

• As shown in the figure, the client wants to send data to the server. Now, the weakest link in a wireless network is from the client to the access point.
• Here, an attacker wants to capture the client’s data and is sitting between the client and the access point. If there is no encryption between the client and the access point, the attacker can read or modify the data.
• To provide wireless security, WEP (Wireless Equivalent Privacy and Wireless Protected Access) is used.
• WEP is not secure, as it is easy to crack. So, to encrypt the data, you can use WPA or WPA2 between the client and the access point.
• Whenever the client connects to the access point, the access point asks the client to enter a password. If the access point asks for a password, the client can be sure that the link for data transmission is encrypted, otherwise, the link is open and can be sniffed by an attacker.

WPA and WPA2

WPA and WPA2 are advanced security protocols. WEP had serious security issues, so WPA was introduced and replaced WEP.

• In WEP, the size of the initialization vector (IV) was smaller, and in WPA, the IV was larger. WPA uses an encrypted hash mechanism.
• WPA uses a 128-bit key for encryption, and encryption is done using the RC4 algorithm with TKIP (Temporal Key Integrity Protocol). Originally, TKIP was designed to improve security in WPA compared to WEP.
• TKIP adds a sequence number to each packet that is transmitted to prevent replay attacks and duplication. It implements a 64-bit Message Integrity Check (MIC) to verify that the data has not tampered during transmission.
• Unfortunately, security issues arose with WPA. So, WPA2 was introduced which is an enhancement of WPA.
• The WPA2 cipher uses the AES (Advanced Encryption Standard) algorithm and counter mode with Block Chaining Message Authentication Code Protocol (CCMP). Here, CCMP replaced the functionality of TKIP.
• CCMP provides data privacy using AES, authentication, and access control. The plaintext block and key size in WPA2 are 128-bit.
• If you use WPA2 security for personal work, you can use WPA2-PSK which is a pre-shared key. If an enterprise use WPA2-802.1X, it authenticates users individually to servers like RADIUS, TACACS+, etc.

The below diagram shows WPA2-802.1X security.

• As shown in the figure, the authentication server contains a database of authorized users. The PC-1 sends his username and password to the access point.
• The access point forwards the user credentials to the authentication server. Once, the authentication server authenticates the user, the user can communicate with the internal network.
• The protocol between the access point and the authentication server is usually the AAA (Authentication, Authorization, and Accounting) protocol.

Session Key

When the user wants to connect to the wireless network, he must prove his authentication to the authentication server by entering the shared network password or his password. Here the master key is created based on the password. But the master key is not much secure and is not used to directly encrypt the packet. The session key is used for a particular amount of time, known as a session. The session key is used as long as the user is communicating over a wireless network.

The figure below shows how the session key is generated.

• As shown in the figure, the session key is calculated using the four-handshake.
• The access point AP sends a random number (initialization vector) to the client for identification.
• The client calculates the session key Ks based on the received initialization vector, MAC address, and master key.
• After computing the session key Ks, the client passes its initialization vector to the access point, and the access point performs the same calculation to generate the same session key.
• The client’s message is protected with Message Integrity Check (MIC). MIC is based on the session key. MIC is similar to Message Authentication Code (MAC).
• Once the AP has verified the client, it sends the group key Kg to the client. The client, after receiving the group key, sends an acknowledgment to the AP.

Bluetooth Security

Bluetooth security is a major issue when devices are connected over short distances. For example, the PC-1 is typing mail using wireless Bluetooth keyboard with no security at all. Now, PC-2 is in range of PC-1, so PC-2 can read everything that PC-1 is typing.

• In a Bluetooth network, a passkey is used if two devices want to connect. When two devices want to establish a channel for communication, both checks to see if the other knows the passkey.
• If someone knows the passkey, the negotiation begins as to whether the channel will be encrypted, message integrity, or both.
• After negotiation, both devices select a random 128-bit session key, of which some bits may be public.
• To provide encryption in Bluetooth, it uses the E0 algorithm and for integrity, it uses SAFER+. E0 and SAFER+ are traditional symmetric-key block ciphers.
• Bluetooth security is maintained in applications that require entering a PIN code from the keyboard to complete a transaction.