1. What is Computer Security ?

Ans:

Computer security basically is the protection of computer systems and information from harm, theft, and unauthorized use. It is the process of preventing and detecting unauthorized use of your computer system.

2. What is Network Security ?

Ans:

Network security is a broad term that covers a multitude of technologies, devices and processes. In its simplest term, it is a set of rules and configurations designed to protect the integrity, confidentiality and accessibility of computer networks and data using both software and hardware technologies.

3. Explain CIA Model.

Ans:

CIA stands for confidentiality, integrity, and availability
Confidentiality:Confidentiality refers to an organization’s efforts to keep their data private or secret. In practice, it’s about controlling access to data to prevent unauthorized disclosure. Typically, this involves ensuring that only those who are authorized have access to specific assets and that those who are unauthorized are actively prevented from obtaining access.
Integrity: In everyday usage, integrity refers to the quality of something being whole or complete. In InfoSec, integrity is about ensuring that data has not been tampered with and, therefore, can be trusted. It is correct, authentic, and reliable.
Availability: availability means that networks, systems, and applications are up and running. It ensures that authorized users have timely, reliable access to resources when they are needed.

4.What is Passive Attacks ?

Ans:

A Passive attack attempts to learn or make use of information from the system but does not affect system resources. Passive Attacks are in the nature of eavesdropping on or monitoring of transmission. The goal of the opponent is to obtain information is being transmitted.

5.What is Active Attacks?

Ans:

An Active attack attempts to alter system resources or effect their operations. Active attack involve some modification of the data stream or creation of false statement.

6. What are the different types of Active Attack ?

Ans:

1.Masquerade : Masquerade attack takes place when one entity pretends to be different entity. A Masquerade attack involves one of the other form of active attacks.
2. Modification of messages: It means that some portion of a message is altered or that message is delayed or reordered to produce an unauthorised effect.
3. Repudiation : This attack is done by either sender or receiver. The sender or receiver can deny later that he/she has send or receive a message.
4. Replay : t involves the passive capture of a message and its subsequent the transmission to produce an authorized effect.
5. Denial of Service : It prevents normal use of communication facilities. This attack may have a specific target. For example, an entity may suppress all messages directed to a particular destination.

7. What are the different types of Passive Attack ?

Ans:

1.The release of message content : Telephonic conversation, an electronic mail message or a transferred file may contain sensitive or confidential information. We would like to prevent an opponent from learning the contents of these transmissions.
2. Traffic analysis : uppose that we had a way of masking (encryption) of information, so that the attacker even if captured the message could not extract any information from the message. The opponent could determine the location and identity of communicating host and could observe the frequency and length of messages being exchanged.

8.What is mono-alphabetic substitution techniques ?

Ans:

A mono-alphabetic cipher (aka simple substitution cipher) is a substitution cipher where each letter of the plain text is replaced with another letter of the alphabet. It uses a fixed key which consist of the 26 letters of a “shuffled alphabet”.

9.What is Ceaser cipher?

Ans:

The Shift (or Caesar) Cipher is another monoalphabetic substitution cipher. Although more secure than the Atbash Cipher, it is still an easy cipher to break, especially by today's standards. Originally, it was used by Julius Caesar for sending encrypted messages to his troops, as recorded by Suetonius.
For a Caesar shift we have a key, which makes the cipher stronger than the Atbash Cipher. The key is the number by which we shift the alphabet, since this provides a unique way to describe the ciphertext alphabet easily.

10.What is Playfair cipher?

Ans:

In This Schema pairs of letter are encrypted instead of single letters as in the case of simple substitution cipher.