Sunday, February 28, 2016

WEP vs WPA vs WPA2

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By now, we have already discussed about Wardriving and how wireless networks can be hacked using Wardriving. (The article can be found here : Wardriving ) We also discussed that, it is always a good practice to use an up-to-date encryption for routers if we want to safeguard our wireless networks. And, this is where WEP, WPA and WPA2 comes into picture.

Let's discuss in detail what WEP, WPA and WPA2 basically are, how are they different from each other and which one to go for.

What is the difference between WEP, WPA and WPA2 ?

Let's understand first what WEP, WPA and WPA2 basically are and how they work. Then it would be easier to understand the difference.

What is WEP ?

WEP stands for Wired Equivalent Privacy. WEP is a popular security algorithm for wireless networks and it was designed for providing data confidentiality for wireless networks. Earlier it was widely used and was the first security choice given to Wi-Fi users. But, later it was supersaded by WPA and WPA2.

WEP uses a 64 bit, 128 bit, 152 bit or 256 bit WEP key. It uses stream cipher RC4 for confidentiality. The WEP key is first concatenated with the Initialization Vector and then the whole keystream is XOR'ed with plaintext to get the encrypted value. The diagram looks something like that of given below :

Length of the Initialization Vector normally is 24 bit. This would mean, for a 64 bit WEP, the WEP key length is 40 bit, for 128 bit WEP, the key length is 104 bit and for 256 bit WEP, the key length is 232 bit.

For 64 bit WEP, user normally enters the key as 5 ASCII characters, which is then converted into 5 x 8 = 40 bit WEP key and then the key is concatenated with 24 bit Initialization Vector. The 64 bit keystream is then XOR'ed with the plaintext to get the encrypted value.

Similarly, for 128 bit WEP, user enters 13 ASCII characters and for 256 bit WEP, user enters 29 ASCII characters.

WEP uses mainly two types of authentication : Open System Authentication and Shared Key Authentication.

For Open System Authentication effectively no authentication occurs. The user rather provides WEP keys to encrypt data frames.

For Shared Key Authentication typically the steps below are followed for authentication :

  • The client sends authentication request to Access Point.
  • The Access Point responds with a cleartext challenge.
  • The client encrypts the challenge text with WEP keys and sends it back.
  • The Access Point decrypts the response and on successful verification authentication happens.

It may seem that Shared Key Authentication is a better option, as Open System Authentication effectively offers no authentication. But, rather the opposite is true. In case of Shared Key Authentication, challenge frames can be captured at the time of authentication and from that keystream can be derived. So, it is advisable to opt for Open System Authentication.

How secure is WEP ?

WEP is proved to be a weaker algorithm. Inspite of using increased key size and revised algorithms, several security flaws were found in WEP. WEP is highly vulnerable and it is strongly advisable to upgrade systems to WPA or WPA2 for security.

What are WPA and WPA2 ?

WPA and WPA2 stands for Wi-Fi Protected Access and Wi-Fi Protected Access II. These are two security protocols developed by Wi-Fi Alliance. (Wi-Fi Alliance is a non-profit organization that promotes Wi-Fi technology and certifies Wi-Fi products after they conform to certain standards of interoperability). WPA and WPA2 was defined in response to security holes found in WPA and WPA2.

WEP uses fixed WEP keys entered by users at the Access Points to encrypt the data packets. But, WPA uses Temporal Key Integrity Protocol or TKIP for encryption. It dynamically generates a 128 bit key for each packet and the key keeps changing for each packet. As a result, WPA does not have the security vulnerability that WEP previously had.

WEP uses CRC or Cyclic Redundancy Check to ensure data integrity. But, the problem with CRC is it fails to provide sufficient data integrity guarantee. In WPA, CRC is replaced with a message integrity check algorithm called Michael. Michael is a much stronger algorithm than CRC, though not as strong as the algorithm used in WPA2.

WPA2 is designed to replace WPA. WPA2 includes AES based encryption mode with strong security. WPA2 is able to provide even more strict security than WPA.

How secure are WPA and WPA2 ?

As discussed earlier, WPA and WPA2 are designed in response to the security vulnerabilities found in WEP. So, both of them are more secure than WEP. In fact, use of WEP is deprectaed and all devices should be upgraded from using WEP.

If we compare WPA and WPA2, WPA2 uses algorithm stronger than WPA. And it ensures even more better security than WPA.

So, in short, among WEP, WPA and WPA2, use of WEP is deprecated. One should instead go for either WPA and WPA2. And, if we compare WPA and WPA2, WPA2 is the most secure. Hope this helps.

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