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WorksheetsUNIT–I: Computer & Network Security Concepts (Q1–Q15)
Total questions: 77
Worksheet time: 39mins
Computer security primarily aims to protect
Hardware only
Software only
Data and resources
Network cables
Which of the following is NOT a security goal?
Confidentiality
Integrity
Availability
Scalability
Confidentiality ensures that information is
Modified correctly
Available to everyone
Accessible only to authorized users
Backed up regularly
Integrity refers to
Prevention of data disclosure
Prevention of unauthorized data modification
Data availability
System uptime
Availability ensures that
Data is encrypted
Authorized users can access data when needed
Data is hidden
Data is compressed
Which security property ensures accountability?
Integrity
Authentication
Non-repudiation
Confidentiality
Active attacks involve
Eavesdropping
Traffic analysis
Modification of data
Monitoring only
Which of the following is an example of a passive attack?
Denial of Service
Replay attack
Traffic analysis
Message modification
Security policy defines
Encryption algorithms
Rules for access and behavior
Hardware configuration
Firewall ports
Threat refers to
A weakness in the system
A potential violation of security
A security control
An encryption method
Vulnerability is
A system strength
A security service
A system weakness
A firewall rule
Risk is defined as
Threat × Vulnerability
Vulnerability × Asset
Threat × Asset
Asset × Security
Which component enforces security policy?
Threat
Mechanism
Vulnerability
Attack
Which is NOT a computer security objective?
Confidentiality
Integrity
Availability
Compression
OSI security architecture was covered by
Security Attacks
Security Services
Security Mechanisms
All
Security attacks are classified into
Logical and Physical
Passive and Active
Internal and External
Software and Hardware
Masquerade attack involves
Data deletion
Pretending to be another entity
Message replay
Traffic analysis
Replay attack means
Data modification
Resending captured messages
Blocking communication
Stealing passwords
Which attack modifies messages?
Traffic analysis
Masquerade
Message modification
Release of message contents
OSI security services are defined to counter
Vulnerabilities
Threats
Attacks
Risks
Which is NOT an OSI security service?
Authentication
Access Control
Routing
Confidentiality
Authentication ensures
Data secrecy
Correct identity of users
Data availability
Message encryption
Access control prevents
Unauthorized use of resources
Data encryption
Message authentication
Key generation
Which service ensures data is not altered?
Confidentiality
Integrity
Authentication
Availability
Security mechanisms are used to
Detect attacks
Prevent attacks
Recover from attacks
All of the above
Encryption is used to provide
Integrity
Confidentiality
Availability
Authentication only
Digital signatures provide
Confidentiality only
Integrity and non-repudiation
Availability
Compression
Network security model includes
Sender, receiver, attacker
Encryption algorithm
Key management
All of the above
Key management deals with
Key generation and distribution
Encryption only
Decryption only
Hashing
Symmetric encryption uses
Two different keys
One public key
One shared secret key
No key
Asymmetric encryption uses
One secret key
Two related keys
No keys
Same key for all users
Which is NOT a security mechanism?
Encipherment
Digital signature
Routing
Access control
Symmetric cipher model uses
Public key
Private key
Shared secret key
Hash value
Caesar cipher is a
Transposition cipher
Substitution cipher
Block cipher
Stream cipher
In substitution cipher
Characters are rearranged
Characters are replaced
Bits are shifted
Blocks are encrypted
Playfair cipher encrypts
Single letters
Letter pairs
Words
Bits
Transposition cipher works by
Replacing characters
Rearranging characters
Encrypting blocks
Using keys only
Rail fence cipher is a
Substitution cipher
Transposition cipher
Block cipher
Stream cipher
Steganography hides
Key
Cipher
Message existence
Algorithm
Invisible ink is an example of
Cryptography
Steganography
Hashing
Authentication
Digital steganography uses
Images
Audio
Video
All of the above
Classical ciphers are easy to break due to
Key reuse
Mathematical weakness
Limited key space
All of the above
Steganography focuses on
Encrypting data
Compressing data
Hiding communication
Key exchange
Block cipher encrypts data in
Bits
Bytes
Blocks
Streams
DES block size is
32 bits
64 bits
128 bits
256 bits
DES key size is
56 bits
64 bits
128 bits
192 bits
DES is based on
Substitution only
Transposition only
Feistel structure
SPN
DES has how many rounds?
8
12
16
32
Initial permutation in DES is
Optional
Fixed
Random
Key-based
AES stands for
Advanced Encryption Standard
Automated Encryption System
Algorithmic Encryption Scheme
Advanced Encoding Standard
AES block size is
64 bits
128 bits
192 bits
256 bits
AES key sizes are
56 bits only
64, 128 bits
128, 192, 256 bits
256 bits only
AES structure is
Feistel
Stream
Substitution-Permutation Network
Transposition
AES operates on
Bytes
Bits
Characters
Words
AES state matrix size is
2x2
3x3
4x4
8x8
AES round consists of
SubBytes
ShiftRows
MixColumns
All of the above
SubBytes step uses
Key
S-box
Permutation
XOR
ShiftRows provides
Confusion
Diffusion
Authentication
Integrity
MixColumns operates on
Rows
Columns
Bits
Keys
AddRoundKey uses
Substitution
Permutation
XOR operation
Rotation
AES does NOT use
S-box
XOR
Feistel structure
Key expansion
Number of rounds in AES-128 is
8
10
12
14
AES-192 has
10 rounds
12 rounds
14 rounds
16 rounds
AES-256 has
10 rounds
12 rounds
14 rounds
16 rounds
AES key expansion generates
Cipher text
Subkeys
Plaintext
Hash values
AES is considered secure because
Large key size
Strong structure
Resistance to known attacks
All of the above
DES replacement standard is
RSA
AES
Blowfish
RC4
Block cipher modes are used to
Increase speed
Improve security
Reduce key size
Compress data
AES encryption and decryption differ in
Key
Operations order
Block size
Algorithm name
AES does NOT suffer from
Brute force attacks
Known practical attacks
Key schedule
Substitution
DES uses how many S-boxes?
4
6
8
16
AES S-box is based on
Linear algebra
Finite field arithmetic
Permutations
Transposition
Block ciphers ensure
Confidentiality
Integrity
Authentication
Availability
AES is standardized by
ISO
IEEE
NIST
IETF
DES key weakness is due to
Algorithm design
Small key size
Large block size
Complex structure
AES supports which platform?
Hardware only
Software only
Both hardware and software
Network only
Modern cryptography primarily focuses on
Classical ciphers
Manual encryption
Computational security
Steganography
