FIT3031 - Network Security Exam Practice

RSA

Diffie-Hellman

SHA-256

DES

Replay

Modification of Message

Denial of Service

All of the above

The encryption key is the same as decryption key

Symmetric key encryption is slower than asymmetric key encryption

AES can be speed up using hardware module

All of the above statements are not true

SNOW 3G

AES

3DES

ZUC

Key distribution

Integrity

Efficiency

All of the above

CWI Amsterdam and Google had performed a collision attack against SHA-1, publishing two dissimilar PDF files which produce the same SHA-1 hash.

CWI Amsterdam and Google had invented a polynomial time algorithm to find two different integers which produce the same SHA-1 hash.

CWI Amsterdam and Google had performed a one-wayness attack against SHA-1, such that given any random 160-bit string, they can re-construct a PDF file which produces this SHA-1 hash.

CWI Amsterdam and Google had invented a polynomial time algorithm to find the input of the hash function x, for any given 160-bit integer y such that H(x)=y where H( ) is the SHA-1 function.

Factorisation

Subset sum

Discrete logarithm (DL)

Learning with errors (LWE)

Application

TCP

Network Layer (IP)

Physical

Digital Signature

Email Security

Wireless LAN Security

Digital Security

Both A and B

Both B and C

Both A and C

All of the above

MIME

HTTP

TELNET

Internet Protocol

Man-in-the-middle

SQL Injection

Denial of Service

Side Channel

A virus cannot be spread without a human action, but a worm has the capacity to travel without any human action.

A virus does not have the dormant phase, but a worm does have.

In the propagation phase, a virus searches for other systems but a worm only searchers for other programs running within the same system.

All of the above are correct

Cannot protect from attacks bypassing it

Cannot protect against internal threat

All of the above are limitations of a firewall

There is no limitation of a firewall

Confidentiality and Integrity

Confidentiality and Availability

Integrity and Availability

A. The act of keeping unauthorised personel out of a system.

B. The act of allowing only authorised users into a system.

C. Authentication

All of the above

Wireless security

Physical security

Human input errors

Only decryption can be performed on the ciphertexts

The adversary can only access to the ciphertexts

The adversary can only decrypt chosen ciphertexts

Symmetric block encryption

Radix-64

Digital signatures

Cipher mode

Transport mode

Tunnel mode

VPN server should be placed in front of firewall if the firewall needs to inspect the packet payloud.

VPN server can only be established by IP security.

VPN can build multiple overlaying networks that share the same physical network.

Transport layer security (TLS) only secures communication between email servers and does not protect between client and server. This means all intermediate hops see plaintext. Hackers and government agencies can utilise this to their advantage. Google uses their key to encrypt emails and can decrypt the emails when requested.

During a TCP flood attack the attacker repeatedly send SYN packets to every port on the target server, often using fake IP addresses. These packets appear legitimate to the server as it tries to establish communication with a SYN-ACK packet. This basically overloads the server and it cannot establish communication due to the large amount of requests occurring.

A TCP flooding attack occurs by an attacker establishing a worm inside the victim system. This worm repeatedly attempts to connect to the system via SYN-ACK packets. These appear legeitimate as they come from within the host system and therefore bypass protection like firewalls and IPSec. This constant connections overload the systems resources causing it to reach capacity, and not be able to accept any legitimate connections.

If there are 5 intermediate Tor routers between the user and web server, the middle one knows neither the user IP nor the server IP.

For per communication session, each TOR router will use its own key to encrypt the message.

Tor can hide the IP address of the users from all intermediate Tor routers.

Alice can use public key of Bob to encrypt the private message encryption key in the presence of MITM attackers.

A security association is defined by the HMAC output that’s computed on the packets

Two parties can run the DH key exchange protocol to generate the key after mutual verification of their identities.

The certificate is installed on your mobile phone’s operating system.

The certificate is loaded from a USB, which is mailed from the CA service provider.

The certificate is sent by a chat bot via an end-to-end encrypted messaging app.

IPSec-based VPN reveals the IP address of the sender host.

IPSec-based VPN prevents from traffic analysis.

IPSec-based VPN reveals the IP addresses of the gateways which establish the tunnel.

The signature cannot be applied on the compressed message.

The compression algorithm might not be deterministic.

The compression algorithm can reduce the redundancy of the message.

Checksum is not encrypted

Checksum only checks some parts of the payload

Checksum itself can be changed and forged

The sequence number of packets cannot be a negative number.

The sliding window will be moved based on a time parameter defined in advance, e.g., after 1 minute, the window is advanced.

The receiver will accept the packets with a sequence number within the current sliding window and mark them as “received”.

Allow content filtering on encrypted emails

Ensure the confidentiality of all email fields

Provide a distributed key management service

The encryption and decryption key remains secret

Both parties in a connection are confident about the security of their communication

The message m exchanged between two parties remains secret during the transmission

Firewalls

Recycle list of half-opened connections

SYN cookies

Allocate backlog memory to a large amount

Encryption of IP header

Sliding window replay mechanism

Compression takes place before encryption to reduce the size of the message.

Compression is done prior to encryption to reduce redundancy. Compressing after encryption would mean the encryption would also have to be compressed, which would lower efficiency and speed.

Compression is done prior to encryption to increase the validity of the encryption.

Misuse

Leakage

No forward secrecy

Lack of non-repudiation and authentication in compromised scenarios

Lack of encryption

Headers can be targeted by hackers to reveal IP addresses

Messages Authentication (Integrity)

Key Management (Authenticity)

Anti-replay (Availability)

ESP tunnel mode encrypts the IP paylod but not the IP header

ESP tunnel mode allows for traffic analysis

ESP tunnel mode disables traffic analysis

ESP tunnel mode authenticates the IP payloud and selected portions of the IP header

Authenticates entire IP packet

Encrypts IP payload

Encypts entire IP packet

Authenticates IP payloud and selected portions of the IP header