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(d) all of these

56 bits are used by DES algorithm

The DES key is apparently 64 bits.

DES was introduced by FIPS

Alternative statement analyses the problem into two cases. Case analysis statement generalizes it to multiple cases. Case analysis splits the problem into an exhaustive set of disjoint cases. For each case, the problem is solved independently. If Cl, C2, and C3 are conditions, and S1, S2, S3 and S4 are statements, a 4 – case analysis statement has the form,

1. case C1 

2. S1 

3. case C2 

4. S2 

5. case C3 

6. S3 

7. else 

8. S4

The conditions C1, C2, and C3 are evaluated in turn. For the first condition that evaluates to true, the corresponding sttement is executed, and the case analysis statement ends. If none of the conditions evaluates to true, then the default case S4 is executed.

1. The cases are exhaustive: at least one of the cases is true. If all conditions are false, the default case is true.

2. The cases are disjoint: only one of the cases is true. Though it is possible for more than one condition to be true, the case analysis always executes only one case, the first one that is true. If the three conditions are disjoint, then the four cases are (1) C1, (2) C2, (3) C3, (4) (not C1) and (not C2) and (not C3).

(c) Translator

There are 3 types of payment frauds

encryption algorithm

Transport Layer Security

DES was introduced in 1976

(b) Assignment

(c) Iterative

(b) Tampering

(b) Pseudo code

There are three important control flow statements.

Distributed Denial of Service

Data Encryption standard was introduced in America

(d) Hackers demand ransom from the victim

(a) Conditional

After decomposing a problem into smaller subproblems, the next step is either to refine the subproblem or to abstract the subproblem.

1. Each subproblem can be expanded into more detailed steps. Each step can be further expanded to still finer steps, and so on. This is known as refinement

2. We can also abstract the subproblem. We specify each subproblem by its input property and the input – output relation. While solving the main problem, we only need to know the specification of the subproblems. We do not need to know how the subproblems are solved.

S1 ; S2 ; S4

Case Analysis statement generalizes the problem into multiple cases. Case Analysis splits the problem into an exhaustive set of disjoint cases.

Case analysis statement generalizes the statement into multiple cases.

After an algorithmic problem is decomposed into subproblems, we can abstract the subproblems as functions

Distributed Denial of Service (DDoS) Attacks: 

It is a process of taking down an E-Commerce site by sending continious overwhelming request to its server. This attack will be conducted from numerous unidentified computers using botnet. This attack will slow down and make the server inoperative. DDoS attacks is also called as network flooding.

(b) Flowchart

(b) Pseudo code

(a) Flow chart

(d) Ctrl + S

Data:

Algorithms take input data, process the data, and produce output data. Computers provide

instructions to perform operations on data. 

For example, there are instructions for doing arithmetic operations on numbers, such as add, subtract, multiply and divide. There are different kinds of data such as numbers and text.

Variables:

Variables are named boxes for storing data. When we do operations on data, We need to store the results in variables. The data stored in a variable is also known as the value of the variable. We can store a value in a variable or change the value of variable, using an assignment statement.

Control flow:

An algorithm is a sequence of statements. However, after executing a statement, the next statement executed need not be the next statement in the algorithm. The statement to be executed next may depend on the state of the process. Thus, the order in which the statements are executed may differ from the order in which they are written in the algorithm. This order of execution of statements is known as the control flow.

There are three important control flow statements to alter the control flow depending on the state.

1. In sequential control flow, a sequence of statements are executed one after another in the same order as they are written.

2. In alternative control flow, a condition of the state is tested, and if the condition is true, one statement is executed; if the condition is false, an alternative statement is executed.

3. In iterative control flow, a condition of the state is tested, and if the condition is true, a statement is executed. The two steps of testing the condition and executing the statement are repeated until the condition becomes false.

Functions:

The parts of an algorithm are known as functions. A function is like a sub algorithm. It takes an input, and produces an output, satisfying a desired input output relation.

1. Double (n)

– – inputs: n is a real number or an integer, n > 0

– – Outputs: y is a real number or an integer such that y = n + n

2. Double (n)

– – inputs: n is a real number or an integer, n > 0

– – Outputs: y is a real number or an integer such that y = 2 x n

1. hypotenuse (a, b)

2. – – inputs: a, b are real numbers, a > 0, b > 0 

3. – – outputs: c² = a² + b² wrhere c is real number, c > 0

The parts of an algorithm are known as functions. A function is like a sub-algorithm. It takes , an input, and produces an output, satisfying a desired input output relation.

1. Quadratic – solve (a, b, c)

2. – – inputs: b² – 4 ac > = 0 where a, b, c are real numbers, a ≠ 0

3. – – outputs: and x² are real numbers such that a(x₁)² + bx₁ + c = 0 and a(x₂)² + bx₂ + c = 0

1. The two outputs q (quotient) and r (remainder) should satisfy the property A = q X B + r, and 

2. The remainder r should be less than the divisor B,

0 < r < B

Combining these requirements, we will specify the desired input-output relation as – 

outputs: A = q X B + r and 0 < r < B.

The values of the variables when the algorithm starts is known as the initial state, and the values of the variables when the algorithm finishes is known as the final state.

There are three important control flow statements to alter the control flow depending on the state.

1. In sequential control flow, a sequence of statements are executed one after another in the same order as they are written. 

2. In alternative control flow, a condition of the state is tested, and if the condition is true, one statement is executed; if the condition is false, an alternative statement is executed.

3. In iterative control flow, a condition of the state is tested, and if the condition is true, a statement is executed. The two steps of testing the condition and executing the statement are repeated until the condition becomes false.

There are a few basic principles and techniques for designing algorithms.

1. Specification:

The first step in problem solving is to state the problem precisely. A problem is specified in terms of the input given and the output desired. The specification must also state the properties of the given input, and the relation between the input and the output.

2. Abstraction:

A problem can involve a lot of details. Several of these details are unnecessary for solving the problem. Only a few details are essential. Ignoring or hiding unnecessary details and modeling an entity only by its essential properties is known as abstraction. For example, when we represent the state of a process, we select only the variables essential to the problem and ignore inessential details.

3. Composition:

An algorithm is composed of assignment and control flow statements. A control flow statement tests a condition of the state and depending on the value of the condition, decides the next statement to be executed.

4. Decomposition:

We divide the main algorithm into functions. We construct each function independently of the main algorithm and other functions. Finally, we construct the main algorithm using the functions. When we use the functions, it is enough to know the specification of the function. It is not necessary to know how the function is implemented.

Specification format:

We can write the specification in a standard three part format:

1. The name of the algorithm and the inputs

2. Input : the property of the inputs

3. Output : the desired input – output relation

The first part is the name of the algorithm and the inputs. The second part is the property of the inputs. It is written as a comment which starts with – inputs: The third part is the desired input – output relation. It is written as a comment which starts with – outputs:. The input and output can be written using English and mathematical notation.

(d) variables

(d) Programming Languages

(a) Sequential

(b) iterative

(c) encapsulation

There are 4 Algorithmic designing techniques.

(d) Both a and b

Answer is (b) 5, 4

Let P be the required property of the inputs and Q the property of the desired outputs.

Format of specification of an algorithm: 

1. Algorithm name (Inputs)

2. Inputs – P

3. Outputs – Q

(d) The name of the algorithm and the inputs