(4 parts a,c,d) please show all work. (17) 4. Answ need more space): er the foll
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(4 parts a,c,d) please show all work.
(17) 4. Answ need more space): er the following questions in the space provided (continue on the backs of pages if you a) What does the acronym SSTF stand for? Give one significant advantage and one significant disadvantage of the SSTF algorithm. b) Name 3 disadvantages associated with linked allocation of disk blocks for files. Dee not support diedt acess slower when d labityues pinter coul be dharegedl. oe) not when, us ed for large files Space required Poc pointers issues-- c) What is the difference between symmetric and asymmetric encryption? Which is more computationally expensive to implement and why? d) What is a trap door? Why are trap doors dangerous and why are they hard to detect/avoid?Explanation / Answer
a) SSTF is the disk scheduling algorithm that stands for Shortest Seek Time First. It moves the head to the next location that is closest to the current location.
Advantage:
Average response time of the request decreases as it moves to the request that takes least time to reach
Disadvantage:
There is an overhead of calculating the seek time for there quests before every movement.. Moreover, some of the request with longer seek time may starve.
c) Symmetric encryption uses same key for the encryption as well as decryption. Both the sender and the reciever should be aware of this secretkey for exchanging the information.
In assymetric encryption, there are two separate keys, one for encryption and another for decryption. Key value pair s not entirely known by both sender and reciever. Sender knows the key to encrypt the data and reciever knows the key to decrypt the data.
Asymmertric encryption is relatively computationally expensive to implement. It use a public key for encryption and a private key for decryption, Public key and private keys are connected to each other by some mathematics. It is hard but not impossible to derive the private key from the public. So, assymetric algorithms are designed keeping it in mind. They are designed ensuring hih computation to get private key from public key. So, algorithm desoigned to encryption is also computationally expensive to implement.
d) A trap door is a piece of code, not required as a part of program, left by the programmer in the code for convenience during the testing and debugging phase. It is also known as backdoor.
Trapdoor is dangerous as it might act as a loophole in the security of the software. Security of the software can be compromised by the hacker using backdoor. Moreover they are harder to detect that make them more dangerous. Once the security hole is introduce, our security is compromised and hacker can gain the access to our data.
Trap doors are harder to avoi/detect as the hackers enters the system without the knowledge and we are not sure of the presence untill we get some evidence. Trapdoors are bits of code that are used to ensure the proper functioning of the software. Whatever we do, tehre are still chances of a person to forget some bits in the code.
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