TAILIEUCHUNG - Scalable voip mobility intedration and deployment- P18

Scalable voip mobility intedration and deployment- P18: The term voice mobility can mean a number of different things to different people. Two words that can be quite trendy by themselves, but stuck together as if forgotten at a bus station long past the last ride of the night, the phrase rings a number of different, and at times discordant, bells. | 170 Chapter 5 Outsider Rejection No wireless device other than a trusted sender can send a message correctly encrypted. Authenticity and Forgery Protection The recipient can prove who the original composer of the message is. Integrity The message cannot be modified by a third party without the message being detected as having been tampered with. Replay Protection A older but valid message cannot be resent by an attacker later thus preventing attackers from replaying old transactions. Some of these properties are contained in how the encryption keys get established or sent from device to device and the rest are contained in how the actual encryption or decryption operates. Wi-Fi Security Technologies Let s start with the earliest security for Wi-Fi. It is useful to read about WEP the first and oldest method for Wi-Fi security to understand the basic terms and concepts for wireless security in general. WEP WEP Wired Equivalent Privacy was the first attempt to secure . Unfortunately the privacy it provided was neither equivalent to wired nor very good. Its very design does not protect against replays meaning that an attacker can record prior valid traffic and replay it later getting the network to repeat actions such as charging credit cards without detecting it. Furthermore WEP uses for encryption RC4 an algorithm that was not designed to be used in the way WEP uses it leading to ways of reverse-engineering and cracking the encryption without the key. Finally WEP uses a very poor message integrity code. All of that said WEP is a good place to look to learn the mechanics of security in as the later and better security additions replaced the broken pieces but did not destroy the framework. NOTE It is the author s recommendation to not use WEP in existing or new networks under any circumstances because of the known flaws. Please consider the studying of WEP to be an academic exercise at this point and do not allow vendors to talk you into .

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