Question 1

Why is quantum computing a threat to RSA?

Answer : **D**

Question 2

As a network administrator, you have implemented WPA2 encryption in your corporate wireless network. The WPA2's ________ integrity check mechanism provides security against a replay attack.

Answer : **A**

CBC-MAC

https://en.wikipedia.org/wiki/CBC-MAC

A cipher block chaining message authentication code (CBC-MAC) is a technique for constructing a message authentication code from a block cipher. The message is encrypted with some block cipher algorithm in CBC mode to create a chain of blocks such that each block depends on the proper encryption of the previous block. This interdependence ensures that a change to any of the plaintext bits will cause the final encrypted block to change in a way that cannot be predicted or counteracted without knowing the key to the block cipher. Using in WPA2 for integrity check and provides security against a replay attack.

Question 3

____________cryptography uses one key to encrypt a message and a different key to decrypt it.

Answer : **B**

Asymmetric

https://en.wikipedia.org/wiki/Public-key_cryptography

Public-key cryptography, or asymmetric cryptography, is a cryptographic system that uses pairs of keys: public keys, which may be disseminated widely, and private keys, which are known only to the owner. The generation of such keys depends on cryptographic algorithms based on mathematical problems to produce one-way functions. Effective security only requires keeping the private key private; the public key can be openly distributed without compromising security.

Question 4

If the round function is a cryptographically secure pseudorandom function, then ___________ rounds is sufficient to make the block cipher a pseudorandom permutation.

Answer : **D**

3

https://en.wikipedia.org/wiki/Feistel_cipher

Michael Luby and Charles Rackoff analyzed the Feistel cipher construction, and proved that if the round function is a cryptographically secure pseudorandom function, with Ki used as the seed, then 3 rounds are sufficient to make the block cipher a pseudorandom permutation, while 4 rounds are sufficient to make it a 'strong' pseudorandom permutation (which means that it remains pseudorandom even to an adversary who gets oracle access to its inverse permutation). Because of this very important result of Luby and Rackoff, Feistel ciphers are sometimes called Luby--Rackoff block ciphers.

Question 5

What is a "Collision attack" in cryptography?

Answer : **D**

Collision attacks try to find two inputs producing the same

https://en.wikipedia.org/wiki/Collision_attack

A collision attack on a cryptographic hash tries to find two inputs producing the same hash value, i.e. a hash collision. This is in contrast to a preimage attack where a specific target hash value is specified.

Question 6

MD5 can best be described as which one of the following?

Answer : **B**

Hashing algorithm

https://en.wikipedia.org/wiki/MD5

The MD5 message-digest algorithm is a widely used hash function producing a 128-bit hash value. Although MD5 was initially designed to be used as a cryptographic hash function, it has been found to suffer from extensive vulnerabilities. It can still be used as a checksum to verify data integrity, but only against unintentional corruption. It remains suitable for other non-cryptographic purposes, for example for determining the partition for a particular key in a partitioned database.

Question 7

What must occur in order for a cipher to be considered 'broken'?

Answer : **C**

Finding any method that is more efficient than brute force

https://en.wikipedia.org/wiki/Cryptanalysis

Bruce Schneier notes that even computationally impractical attacks can be considered breaks: 'Breaking a cipher simply means finding a weakness in the cipher that can be exploited with a complexity less than brute force.'

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Total 206 questions

Total 206 questions