Other Programming & Computer Science Answers

A student is learning about the `three-way handshake' done when a client and server connect to each other using the TCP network protocol. The student says

“I don't understand why the initial sequence numbers (ISNs) seem to be pseudorandom numbers. Wouldn't it be easier for both client and server to have an ISN of 1?”

Write an explanation that will help this student understand why network security is

improved by having ISNs that look random.

A web application requires users to log in with their email address and a password. For security reasons, the application stores SHA-1 hashes rather than plaintext passwords. It also computes the hash for a combination of the password and some random salt, rather than the password alone.

Describe two simple improvements that should be made to this authentication scheme.

The machine in (a) can perform 270 million decryptions per second. It can check the output to see whether decryption was successful 20 million times per second. Using this information, and the information given in (a), estimate the likely size of the key, quoting your result as a whole number of bits. Show all your working.

A machine that can crack symmetric cipher keys by brute force is tested with three different samples of ciphertext. Each sample was encrypted with the same cipher. A different key was used to produce each sample, but the key size was the same for all samples.

In the three trials, the times taken to find the key were recorded as 22.8 hours, 30.9 hours and 42.6 hours. Explain why the times to find the key vary

Q#1

PROGRAMMING TASK:

Q: You have to develop a PROGRAM (in any programming language) that takes a TEXT file (.txt) and performs the following tasks:

1: Remove WHITE SPACES (more than one at any point - two or more).

2: Generate TOKENS for identifier, keywords, numbers and punctuations, and any others.

e.g.

<if, keyword>

OUTPUT: the program should generate a new TEXT file (.txt) containing tokens and the remaining text (e.g. output.txt)

The input file should contain at least 300 words.

Q#2

What's the meaning of GNU, GCC, POSIX in compiler? Explanation required with example?

Q#3

a) Explain what does this regular expression means?

(' ' + '\n' + '\t')+

b) Write a Regular Expression for acceptance of File names in Windows OS.

e.g.

AI Book.exe

new_file.jpg

a Describe the two different contexts in which an elaborate GUI of a management application 

does very little to increase management effectiveness. 

CS208

In your line of work (if you are a worker or employed or self-employed) or in your line of schooling (if you are only a student and not working as well), discuss an example remote control connection that could be useful to you in this era of COVID-19. 

Calculate Waiting Time (WT)  & average waiting time in FCFS, SJF (Preemptive) , SJF (Non preemptive)

Due to Ramadan, your nearby community wants to launch an “Online Grocery Store” so that, people can purchase groceries from home and able to maintain social distance. This precaution will allow reducing the movement of people in Ramadan and minimize the spread of disease COVID-19. The XYZ store will offer various products. The user will be shown a list of products, which can be selected or deselected from the provided list. The user will need to get registered to buy Products. At the end of shopping, the customer can double-check all the Products added into his Cart and verify the total amount before payment. The Store Administrator will manage Products and assign orders to Delivery Boys.

The tasks you have to do are:

1. Extract the main objects (entities) of above system.
2. Find the necessary attributes and functions that need to be associated with each object.
3. Identify the relationships among identified objects.

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