Chapter 6 R17:
Answer
The permanent address is the home of mobile device. This is where the device ‘lives’. The care-of-address is the address given to the mobile device when it enters another network area; in other words ‘roaming away from its’ home network. All data is routed to the permanent address and the home agent then forwards the data/message onto the other network via the care-of-address. The mobile device then directly responds to the correspondent.
The care-of-address is generated and assigned by the foreign network.
Chapter 8 R1:
Answer
Message confidentiality assumes that a message cannot be read by anyone other than the intended recipients. Message integrity assumes that a message cannot be tampered with without the intended recipients knowing.
For example, suppose I need to tell you whether to attack or not. We could use a code where a particular number only you and I know means to attack and one less that means not to attack. This provides message confidentiality if someone intercepts a message say, “51” they have no idea whether that means to attack or not. But it provides no message integrity. If someone knows I’m going to tell you not to attack and knows the message is “51”, he can replace it with “52” and change it to attack.
If we use two completely different numbers one for attack and one for not to attack, we get both confidentiality and integrity. Someone seeing the message, say again “51” couldn’t know whether that was attack or not attack. He also could not change the message to the mean the opposite, since he would have no clue what the other number was.
Algorithms and methods that provide confidentiality are referred to as “encryption” Algorithms and methods that provide integrity are often referred to as “signature”.
It is possible to have confidentiality without integrity. Someone can hand you an encrypted message, and you can start changing bits in the message without knowing what those bit mean. Thus, the...