Solve the following questions on networking.

1: A prime number is called a Mersenne prime if it can be written in the form of 2p -1 (2 raised to the p power 1) for some positive integer p. Use a program that lists all Mersenne primes with p < 31. Note that an int will hold values between-231 and +231-1, so an int variable can be used for this problem. You do not have to use methods in this problem, but you will likely find it easier to use stepwise refinement techniques described in section 5.12 of the text to simplify the problem.

and R2(X, Z). (i) Give two possible advantages for this schema change. [2 marks] (ii) Give two possible disadvantages for this schema change. [2 marks] (iii) Is X a key for R1? Explain. [2 marks] (iv) Is X a key for R2? Explain. [2 marks] (d) Prove that Heath's Rule always holds.

(a) Codd's 1970 paper introduced the Relational Model of data to address the difficulties of building database applications using the technology that was available at the time. (i) What problems were encountered by database developers before Codd introduced the Relational Model? [1 mark] (ii) Describe the basic elements of the Model, and explain what is meant by a relational schema. [4 marks] (iii) Explain how a formal schema can assist both the application database designer and a database application programmer. What if any are the disadvantages of adopting a mathematical description of database structure? [5 marks] (b) In 1976 Peter Chen introduced the Entity Relationship (E-R) Model to support a more natural description of real world data. (i) Describe the basic elements of the Model, and explain some of the choices available to the database designer. encryption module was designed to make TeleGroove messages difficult to read for eavesdroppers. Such messages are character sequences of arbitrary length, encoded using a 5-bit alphabet A = {a0, . . . , a31}. The T1000 module reads blocks of up to 1000 characters at a time into its memory (m0, m1, . . . , m999) and then outputs them again in a different order (mK(0), mK(1), . . . , mK(999)), according to a secret key table K : {0, . . . , 999} {0, . . . , 999} that is shared with the respective recipient of each message. It repeats that process until the block ending with the last character has been processed. (i) What constraint on K ensures that no information is lost? [2 marks] (ii) Identify an ambiguity in the above description and propose a flaw hypothesis regarding a related residual-information vulnerability in this device. [4 marks] (iii) What is the smallest number of blocks that a chosen-plaintext attacker has to send through the device to recover K? Give an example of the content of such blocks and explain how to recover K from them. Enable deletion of consignments' records Persist consignments information in the database 2. Facilitate consignments management Allow sorting the consignments' records by Vendor and Expiry date Allow fast searching for a consignment by Id3. Manage sales Provide a form to register new sales (no need for edit and delete functionality) Persist sale information in database4. Sale composition As a part of sale creation form a user should be able to generate a list of consignments to be used. Consignments' records should be placed into appropriate data structure according to the expiry date and then the required number of consignments (determined by Amount attribute of the sale) should be selected and shown on the form. The user should be notified (e.g. via a message box) if there is not enough milk i.e. all remaining consignments are not sufficient for the order. Persist reminders of the consignments used - update co_remaining attribute to the amount remaining after sale.

Briefly explain (a) the function of a salt value in a password database [3 marks] (b) two examples of covert channels in a file system protocol that is restricted to read-only operations under a mandatory access-control policy [2 marks] (c) three types of common software vulnerabilities.