Chapter 21 Security

Question 1

Why is a key need in encryption?

Answer 1

Key is needed to encrypt code or to decript code

Question 2

What is Plaintext?

Answer 2

Plaintext is data before encryption

Question 3

What is Ciphertext?

Answer 3

Ciphertext is the result of applying an encryption algorithm

Question 4

Which are the main concerns relating to transmission?

Answer 4

Confidentiality
Authenticity
Integrity
Non-repudiation
Availability

Question 5

In encryption what must remain in Public Domain and what must not remain in public domain?

Answer 5

The encryption algorithm must reamain in Public Domain and the Key must remain a secret

Question 6

What happens in Symmetric key encryption?

Answer 6

Only one key used to encrypt and decrypt

Key is a secret between sender and receiver

Question 7

What happens in Asymteric encryption?

Answer 7

The receiver sends the encryption key to the sender in order to encrypt the code so that the receiver would be able to decrypt the message

Question 8

Which are the requirements to ensure condifentiality

Answer 8

Have a complex encryption algorithm and a large number of bits to be used to define the key

Question 9

What happens in a Digital signiture and what is its disadvantage

Answer 9

Private key is only sent to those whom you want to decyphere the code
The disadvantage is that the digital signature associated with an encryption of the whole message

Question 10

What happens in a one-way hash function and what does it do?

Answer 10

Recreates form the message sent a number, uniquely defined for the particular message, called ‘digest’.
Speeds up the process confirming the sender’s identity
The process at the sender’s end of the transmission is outlined
At the receivers end the same hash key function is used to have the same digest if there were no alterations

Question 11

What is TLS and SSL?

Answer 11

TLS Secure Socket Layer protocol is a slightly modified version of SSL Secure Socket Layer protocol.
Provide security in using using the internet

Question 12

Which are the types of malware and what do they do?

Answer 12

Virus
tries to replicate itself other executable code
Worm
runs independentely and propagates to other network hosts
Logic bomb
lies dormant until some condition is met
Trojan horse
eprlacess all or part of a previously useful program
Spyware
collects information and transmits it to another system
Bot
takes control of another computer and uses it o launch attacks

Question 13

Which are the the types of malitous activities?

Answer 13

Phishing
sending an email or electronic message from an apparently legitimate source requesting confidential information
Pharming
setting up a bogus website which appears to be a legitimate site
Keylogger
recording keyboard usage by the legitimate user of the system

Question 14

How can a user introduce a malware inadvertently?

Answer 14

By attaching a portable storage device
By openning an email attachment
By accessing a website
By downloading a file from the internet