What type of cipher does wep use

That "method The Packet injection allowed for WEP to be cracked in times as short as several seconds. This ultimately led to the deprecation of WEP. Python Javascript Linux Cheat sheet Contact. How does WEP wireless security work? Both quotes from the Initialization vector Wikipedia article. Tags: Cryptography Wifi Wep.

Related Russian Caesar cipher Gimli, make it even shorter? WEP encryption scrambles the data transmitted between wireless devices to keep the communication private.

Wireless devices and their wireless client devices use the same WEP key to encrypt and decrypt data. WEP keys encrypt both unicast and multicast messages. Unicast messages are addressed to one device on the network. Multicast messages are addressed to multiple devices on the network. If an intruder passively receives enough packets encrypted by the same WEP key, the intruder can perform a calculation to learn the key and use it to join your network. Because they change frequently, dynamic WEP keys prevent intruders from performing the calculation and learning the key.

Cipher suites are sets of encryption and integrity algorithms designed to protect radio communication on your wireless LAN. Cipher suites that contain only WEP are the least secure. However, the basic WEP construction is flawed, and an attacker can compromise the privacy with little effort.

Note Client devices that are using static WEP cannot use the wireless device when you enable broadcast key rotation. When you enable broadcast key rotation, only wireless client devices that are using Up to 16 VLANs can be assigned.

The bit keys contain 10 hexadecimal digits; the bit keys contain 26 hexadecimal digits. For example, 11aa33bb55 for a bit key. The following attack is also a direct consequence of the problems described in the previous section.

Suppose an attacker knows the exact plaintext for one encrypted message. He can use this knowledge to construct correct encrypted packets. The procedure involves constructing a new message, calculating the CRC, and performing bit flips on the original encrypted message to change the plaintext to the new message. This packet can now be sent to the access point or mobile station, and it will be accepted as a valid packet.

A slight modification to this attack makes it much more insidious. Even without complete knowledge of the packet, it is possible to flip selected bits in a message and successfully adjust the encrypted CRC as described in the previous section , to obtain a correct encrypted version of a modified packet. If the attacker has partial knowledge of the contents of a packet, he can intercept it and perform selective modification on it. For example, it is possible to alter commands that are sent to the shell over a telnet session, or interactions with a file server.

The previous attack can be extended further to decrypt arbitrary traffic. In this case, the attacker makes a guess about not the contents, but rather the headers of a packet. This information is usually quite easy to obtain or guess; in particular, all that is necessary to guess is the destination IP address. Armed with this knowledge, the attacker can flip appropriate bits to transform the destination IP address to send the packet to a machine he controls, somewhere in the Internet, and transmit it using a rogue mobile station.

Most wireless installations have Internet connectivity; the packet will be successfully decrypted by the access point and forwarded unencrypted through appropriate gateways and routers to the attacker's machine, revealing the plaintext. If a guess can be made about the TCP headers of the packet, it may even be possible to change the destination port on the packet to be port 80, which will allow it to be forwarded through most firewalls. The small space of possible initialization vectors allows an attacker to build a decryption table.

Once he learns the plaintext for some packet, he can compute the RC4 key stream generated by the IV used. This key stream can be used to decrypt all other packets that use the same IV. Over time, perhaps using the techniques above, the attacker can build up a table of IVs and corresponding key streams. Despite the difficulty of decoding a 2. The products possess all the necessary monitoring capabilities, and all that remains for attackers is to convince it to work for them.

Although most We were able to confuse the firmware enough that the ciphertext encrypted form of unrecognized packets was returned to us for further examination and analysis. Active attacks those requiring transmission, not just monitoring appear to be more difficult, yet not impossible.

Many Granted, such reverse-engineering is a significant time investment we have not done this ourselves , but it's important to note that it's a one time cost. A competent group of people can invest this effort and then distribute the rogue firmware through underground circles, or sell it to parties interested in corporate espionage. The latter is a highly profitable business, so the time investment is easily recovered.