Joshua Villy
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1 CSI270 Quiz on Quiz 7, created by Joshua Villy on 08/05/2013.

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Joshua Villy
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Quiz 7

Question 1 of 25

1

The process of transforming ciphertext to plaintext is known as:

Select one of the following:

  • Decryption

  • Encryption

  • Key recovery

  • Hashing

Explanation

Question 2 of 25

1

Which of the following statements is true about the Vernam cipher:

Select one of the following:

  • It is a polyalphabetic cipher

  • It is a running-key cipher

  • The encryption key is used for only one message

  • Another name for it is a one-time hash

Explanation

Question 3 of 25

1

What is the minimum key length for a one-time pad?

Select one of the following:

  • 128 bits

  • 64 bits

  • 56 bits

  • The length of the plaintext message

Explanation

Question 4 of 25

1

All of the following statements about the polyalphabetic cipher are true EXCEPT:

Select one of the following:

  • It is a form of one-time pad

  • It is resistant to frequency analysis attacks

  • It uses multiple substitution alphabets

  • It is a type of substitution cipher

Explanation

Question 5 of 25

1

A running-key cipher can be used when:

Select one of the following:

  • The plaintext is longer than the encryption key

  • The plaintext is shorter than the encryption key

  • The plaintext is streaming media

  • The plaintext is changing rapidly

Explanation

Question 6 of 25

1

In modulo arithmetic, when A – B

Select one of the following:

  • 26 is subtracted from the result

  • 100 is added to the result

  • 26 is added to the result

  • 32 is added to the result

Explanation

Question 7 of 25

1

A computer user is listening to an audio broadcast on the Internet through an SSL VPN. The type of encryption cipher used in this case is:

Select one of the following:

  • Block cipher

  • Stream cipher

  • Running key cipher

  • Vernam Cipher

Explanation

Question 8 of 25

1

In an electronic codebook (ECB) cipher, each block of ciphertext:

Select one of the following:

  • Is used to encrypt the next block

  • Is used to encrypt the previous block

  • Is used to decrypt the next block

  • Is not used to encrypt the next block

Explanation

Question 9 of 25

1

The encryption mode where ciphertext output from each encrypted plaintext block in the encryption used for the next block is known as:

Select one of the following:

  • Cipher feedback

  • Output feedback

  • Cipher block chaining

  • Electronic codebook

Explanation

Question 10 of 25

1

Public key cryptography is another name for:

Select one of the following:

  • Secure Sockets Layer

  • Asymmetric cryptography

  • Symmetric key cryptography

  • Kerberos

Explanation

Question 11 of 25

1

Public key cryptography is so-named because:

Select one of the following:

  • It is the world standard for HTTPS

  • It works on all popular computer operating systems

  • It uses an encryption key that can be released to the public

  • The encryption algorithms reside in the public domain

Explanation

Question 12 of 25

1

A security manager is searching for an encryption algorithm to be used to encrypt data files containing sensitive information. Which of the following algorithms should NOT be considered:

Select one of the following:

  • FISH

  • Twofish

  • Blowfish

  • CAST

Explanation

Question 13 of 25

1

A particular encryption algorithm transforms plaintext to ciphertext by XORing the plaintext with the encryption key. This is known as:

Select one of the following:

  • Electronic codebook

  • Cipher block chaining

  • Block cipher

  • Stream cipher

Explanation

Question 14 of 25

1

Two parties that have never communicated before wish to send messages using symmetric encryption key cryptography. How should the parties begin?

Select one of the following:

  • The receiving party should send its public encryption key to the transmitting party

  • Each party should exchange public encryption keys

  • Each party should send the encryption key via the communications channel to the other party

  • One party should transmit the encryption key via an out of band communications channel to the other party

Explanation

Question 15 of 25

1

Two parties that have never communicated before wish to send messages using asymmetric key cryptography. How should the parties begin?

Select one of the following:

  • The receiving party should send its private encryption key to the transmitting party.

  • The transmitting party should send its private encryption key to the receiving party.

  • The receiving party should send its public encryption key to the transmitting party.

  • The transmitting party should send its public encryption key to the receiving party.

Explanation

Question 16 of 25

1

Two parties, Party A and Party B, regularly exchange messages using public key cryptography. One party, Party A, believes that its private encryption key has been compromised. What action should Party B take?

Select one of the following:

  • Request a new public key from Party A

  • Request a new private key from Party A

  • Send a new public key to Party A

  • Send a new private key to Party A

Explanation

Question 17 of 25

1

The Advanced Encryption Standard is another name for which cipher:

Select one of the following:

  • Digital Encryption Algorithm (DEA)

  • 3DES

  • Rijndael

  • International Data Encryption Algorithm (IDEA)

Explanation

Question 18 of 25

1

The Data Encryption Standard:

Select one of the following:

  • Is used by Secure Sockets Layer (SSL) encryption

  • Has been replaced by the International Data Encryption Algorithm (IDEA)

  • Uses a 64-bit encryption key

  • Uses a 56-bit encryption key

Explanation

Question 19 of 25

1

Two parties are exchanging messages using public key cryptography. Which of the following statements describes the proper procedure for transmitting an encrypted message?

Select one of the following:

  • The sender encrypts the message using the recipient’s public key, and the recipient decrypts the message using the recipient’s private key

  • The sender encrypts the message using the sender’s public key, and the recipient decrypts the message using the recipient’s public key

  • The sender encrypts the message using the sender’s private key, and the recipient decrypts the message using the recipient’s private key

  • The sender encrypts the message using the sender’s public key, and the recipient decrypts the message using the sender’s public key

Explanation

Question 20 of 25

1

A stream cipher encrypts data by XORing plaintext with the encryption key. How is the ciphertext converted back into plaintext?

Select one of the following:

  • XORing it with the encryption key

  • XORing it with the inverse of the encryption key

  • ANDing it with the encryption key

  • NANDing it with the encryption key

Explanation

Question 21 of 25

1

The purpose of digitally signing a message is to ensure:

Select one of the following:

  • Integrity of the sender

  • Confidentiality of the message

  • Authenticity of the sender

  • Confidentiality of the sender

Explanation

Question 22 of 25

1

The purpose of digitally signing a message is to ensure:

Select one of the following:

  • Integrity of the message

  • Confidentiality of the message

  • Integrity of the sender

  • Confidentiality of the sender

Explanation

Question 23 of 25

1

The purpose of the Diffie-Hellman key exchange protocol is:

Select one of the following:

  • To decrypt a symmetric encryption key

  • To encrypt a symmetric encryption key

  • To permit two parties who have never communicated to establish public encryption keys

  • To permit two parties who have never communicated to establish a secret encryption key

Explanation

Question 24 of 25

1

An attacker is attempting to learn the encryption key that is used to protect messages being sent between two parties. The attacker is able to create his own messages, get them encrypted by one of the parties, and can then examine the ciphertext for his message. This type of attack is known as:

Select one of the following:

  • Ciphertext only attack

  • Chosen ciphertext attack

  • Chosen plaintext attack

  • Man in the middle attack

Explanation

Question 25 of 25

1

Which is the best approach for two parties who wish to establish a means for confirming the confidentiality and integrity of messages that they exchange:

Select one of the following:

  • Digital signatures

  • Encryption and digital signatures

  • Key exchange

  • Encryption

Explanation