Wireless Network Attack and Defense: WEP strategy

We cannot underestimate the development of wireless network technology. How can we explain how to crack WEP? After the emergence of WLAN technology, "security" has always been a shadow around the word "wireless". Attacks and cracking against security authentication and encryption protocols involved in wireless network technology have emerged. Currently, there may be hundreds or even thousands of articles on how to attack and crack WEP on the Internet, but how many people can truly break WEP's encryption algorithm? Next I will introduce some knowledge about WEP encryption methods, as well as the methods that cainiao can successfully crack the WEP Key as long as they follow the steps. Of course, the ultimate goal is to enable reporters to set security settings to better prevent cracking attacks.

WEP: the initial protector of Wireless Network Security

Compared with wired networks, data is more easily eavesdropped when sent and received over a wireless LAN. To design a complete Wireless LAN system, encryption and authentication are two essential security factors. The most fundamental purpose of applying encryption and authentication technology in a wireless LAN is to enable wireless businesses to reach the same security level as wired businesses. To address this goal, the standard adopted the WEP (Wired Equivalent Privacy: Wired peer-to-peer confidentiality) Protocol to set up a special security mechanism for business flow encryption and node authentication. It is mainly used for the confidentiality of link layer information data in Wireless LAN. WEP adopts symmetric encryption mechanism, and data encryption and decryption adopts the same key and encryption algorithm. WEP uses an encryption key (also known as the WEP Key) to encrypt the data portion of each packet exchanged on the 802.11 Network. After encryption is enabled, two 802.11 devices must have the same encryption key and be configured with encryption. If one device is configured to use encryption and the other device does not, communication fails even if the two devices have the same encryption key. (1)

WEP encryption process

WEP supports 64-bit and 128-bit encryption. For 64-bit encryption, the encryption key is 10 hexadecimal characters (0-9 and A-F) or 5 ASCII characters; for 128-bit encryption, the encryption key is 26 hexadecimal characters or 13 ASCII characters. 64-bit encryption is sometimes called 40-bit encryption; 128-bit encryption is sometimes called 104-bit encryption. 152-bit encryption is not a standard WEP technology and is not widely supported by client devices. WEP relies on the keys shared by both parties to protect the encrypted data. The data encryption process is as follows.

1. Check Summing ).

(1) Integrity Verification and calculation of input data.

(2) combine the input data with the calculated checksum to obtain the new encrypted data, also known as plaintext, which serves as the input for the next encryption process.

2. encryption.

In this process, the plaintext data obtained in the first step is encrypted using an algorithm. Encryption of plaintext has two meanings: encryption of plaintext data to protect unauthenticated data.

(1) run the 24-bit initialization vector and the 40-bit key connection for verification and calculation to obtain the 64-bit data.

(2) input the 64-bit data to the virtual random number generator, which encrypts the checksum and calculation values of the initialization vector and key.

(3) The plaintext and the output encrypted stream of the virtual random number generator after verification and calculation are encrypted by bitwise XOR operation, that is, the ciphertext.

3. transmission. Concatenates the initialization vector and ciphertext to obtain the encrypted data frame to be transmitted and transmit it on the wireless link. (