Oib Part4
- 1.An algorithm for encryption and decryption. Replaces a piece of information (an element in plaintext) with another object, with the intent to conceal meaning.
- A.
Cipher
- B.
Ciphertext
- C.
Decryption
- D.
Encryption
- 2.Suppose that your plaintext is 168 bytes long and you are using DES, how many blocks will be formed for the whole encryption process?
- A.
21
- B.
23
- C.
11
- D.
212
- 3.Which of these is possibly the best password that user can choose
- A.
14G:c*%3wM*-l6g_Bnp?d86
- B.
ALm4tyc?TY
- C.
Nursultan1612
- D.
Option 4
- 4.Which of these is not considered a symmetric-key algorithm
- A.
Vigenerecipher
- B.
RC4
- C.
Caesarcipher
- D.
RSA
- 5.Point out two major advantages of public crypto over symmetric key crypto
- A.
Digital signatures offer only integrity
- B.
With public key crypto, we don‟t need to established a shared key in advance
- C.
Digital signatures offer not only integrity but also non-repudiation
- D.
With public key crypto, we need to established a shared key in advance
- 6.A _____________ is the one-way function, since it is not practical to reverse
- A.
Roundfunction
- B.
FeistelCipher
- C.
DES
- D.
MessageDigest
- 7.If you encrypt a ciphertext using the right key, you will get
- A.
Theplaintext
- B.
Gibberish
- C.
Errormessage
- D.
Option 4
- 8.Which of these statements is NOT TRUE
- A.
It is impossible to break an encryption without a key
- B.
It is possible to try all possible numbers systematically to break the encryption
- C.
Without a key, if hackers are able to obtain the encrypted file, it is possible that they can obtain the program that converts it back
- D.
Even though someone can use the same program used to encrypt the file, it can never re-creates the original file without the secret numb Even though someone can use the same program used to encrypt the file, it can never re-creates the original file without the secret numb
- 9.Operation which maps elements of the plaintext into another is known as ___________.
- A.
Noneofthestatements
- B.
Transposition
- C.
Rearranging
- D.
Substitution
- 10.A form of active wiretapping attack in which the attacker intercepts and selectively modifies communicated data in order to masquerade as one or more of the entities involved in a communication.
- A.
Mandatoryaccesscontrol
- B.
Noneofthestatements
- C.
Intrusiondetectionsystem
- D.
Man-in-the-middleattack
- 11.What is a Modification of messages
- A.
Preventing or inhibiting the normal use or management of communications facilities
- B.
Altering some portion of a legitimate message, or that messages are delayed or reordered, to produce an unauthorized effect.
- C.
Restricting access to resources to privileged entities.
- D.
. One entity pretends to be a different entity
- 12.Indicate the definition for Signature
- A.
Corroborating the source of information; also known as data origin authentication.
- B.
Keeping information secret from all but those who are authorised to see it
- C.
Ensuring information has not been altered by unauthorised or unknown means
- D.
Binding information to an entity
- 13.Indicate the drawbacks of reactive password checking technique
- A.
Any existing passwords remain vulnerable
- B.
Resourceintensive
- C.
Many users will simply ignore the guidelines.
- D.
Users will not be able to remember them
- 14.Using the Vigenère cipher, encrypt the word "expla" using the key leg
- A.
Pbvwe
- B.
Option 2
- C.
Option 3
- D.
Option 4
- 15.A function that is easily computed, but the calculation of its inverse is infeasible
- A.
One-wayfunction
- B.
RC4
- C.
DES
- D.
RSA
- 16.Which of the following statement is NOT TRUE ( 99%)
- A.
RSA encrypts at a speed on par with symmetric cryptosystems
- B.
. No efficient algorithm exists for solving the RSA ciphertext problem
- C.
. Some experts believe that RSA 1024-bit keys may become breakable in the near term
- D.
All of the listed answers are TRUE
- 17.Indicate the definition for Privacy or confidentiality
- A.
Keeping information secret from all but those who are authorised to see it
- B.
Ensuring information has not been altered by unauthorised or unknown means
- C.
Corroborating the source of information; also known as data origin
- D.
Binding information to an entity
- 18.Which of the following are examples of the host dependent malicious programs
- A.
Trapdoor
- B.
LogicBombs
- C.
TrojanHorses
- D.
Rootkit
- 19.Which malicious software is used to cause DoS (Denial of Service) attack against particular web site
- A.
Keylogger
- B.
TrojanHorse
- C.
WORM
- D.
Zombie
- 20.An attack on the key by attempting all possible combinations is called
- A.
A cryptographic key attack
- B.
A brute force attack
- C.
An all combinations attack
- D.
A random key attack
- 21.What is the purpose of Active Attack
- A.
To counter security attacks, and they make use of one or more security mechanisms to provide the service
- B.
To alter system resources or affect their operation.
- C.
To bind information to an entity
- D.
Option 4
- 22.What is the key length in DES
- A.
48-bit
- B.
256-bit
- C.
56-bit
- D.
64-bit
- 23.Indicate the definition for Access control
- A.
Recording the time of creation or existence of information
- B.
Conveyance, to another entity, of official sanction to do or be something
- C.
Endorsement of information by a trusted entity
- D.
Restricting access to resources to privileged entities
- 24.Which of the following statement is TRUE
- A.
Public-key algorithms are susceptible to dictionary attack
- B.
The fastest technique to break public-key algorithms is brute force
- C.
No one has been able to develop a public-key algorithm that has no weaknesses
- D.
Public-key algorithms are suitable to encrypt large data
- 25.Indicate the definition for Authorisation
- A.
Providing timeliness of authorisation to use or manipulate information or resources
- B.
Restricting access to resources to privileged entities
- C.
Endorsement of information by a trusted entity
- D.
. conveyance, to another entity, of official sanction to do or be something
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