Part 4

How do modern cryptographers defend against brute-force attacks?

• Use statistical analysis to eliminate the most common encryption keys.

• Use a keyspace large enough that it takes too much money and too much time to conduct a successful attack.

• Use an algorithm that requires the attacker to have both ciphertext and plaintext to conduct a successful attack.

• Use frequency analysis to ensure that the most popular letters used in the language are not used in the cipher message.

How does a Caesar cipher work on a message?

• Words of the message are substituted based on a predetermined pattern

• Letters of the message are rearranged based on a predetermined pattern

• Letters of the message are rearranged randomly.

• Letters of the message are replaced by another letter that is a set number of places away in the alphabet.

What is the main factor that ensures the security of encryption of modern algorithms?

• complexity of the hashing algorithm

• the use of 3DES over AES

• secrecy of the keys

• secrecy of the algorithm

What is the next step in the establishment of an IPsec VPN after IKE Phase 1 is complete?

• authentication of peers

• detection of interesting traffic

• negotiation of the IPsec SA policy

• negotiation of the ISAKMP policy

Refer to the exhibit. What algorithm will be used for providing confidentiality?

• RSA

• Diffie-Hellman

• DES

• AES

What is the purpose of this command?

"crypto ipsec transform-set MYSET esp-aes 256 esp-md5-hmac"

• It establishes the set of encryption and hashing algorithms used to secure the data sent through an IPsec tunnel.

• It defines the default ISAKMP policy list used to establish the IKE Phase 1 tunnel.

• It establishes the criteria to force the IKE Phase 1 negotiations to begin.

• It indicates that IKE will be used to establish the IPsec tunnel for protecting the traffic.

Which algorithm can ensure data integrity?

• PKI

• MD5

• AES

• RSA

A company implements a security policy that ensures that a file sent from the headquarters office to the branch office can only be opened with a predetermined code. This code is changed every day. Which two algorithms can be used to achieve this task? (Choose two.)

• AES

• SHA-1

• 3DES

• MD5

• HMAC

A network technician has been asked to design a virtual private network between two branch routers. Which type of cryptographic key should be used in this scenario?

• hash key

• symmetric key

• asymmetric key

• digital signature

Which two options can limit the information discovered from port scanning? (Choose two.)

• encryption

• passwords

• authentication

• firewall

• intrusion prevention system