The process of transforming ciphertext to plaintext is known as:
Decryption
Encryption
Key recovery
Hashing
Which of the following statements is true about the Vernam cipher:
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
What is the minimum key length for a one-time pad?
128 bits
64 bits
56 bits
The length of the plaintext message
All of the following statements about the polyalphabetic cipher are true EXCEPT:
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
A running-key cipher can be used when:
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
In modulo arithmetic, when A – B
26 is subtracted from the result
100 is added to the result
26 is added to the result
32 is added to the result
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:
Block cipher
Stream cipher
Running key cipher
Vernam Cipher
In an electronic codebook (ECB) cipher, each block of ciphertext:
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
The encryption mode where ciphertext output from each encrypted plaintext block in the encryption used for the next block is known as:
Cipher feedback
Output feedback
Cipher block chaining
Electronic codebook
Public key cryptography is another name for:
Secure Sockets Layer
Asymmetric cryptography
Symmetric key cryptography
Kerberos
Public key cryptography is so-named because:
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
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:
FISH
Twofish
Blowfish
CAST
A particular encryption algorithm transforms plaintext to ciphertext by XORing the plaintext with the encryption key. This is known as:
Two parties that have never communicated before wish to send messages using symmetric encryption key cryptography. How should the parties begin?
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
Two parties that have never communicated before wish to send messages using asymmetric key cryptography. How should the parties begin?
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.
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?
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
The Advanced Encryption Standard is another name for which cipher:
Digital Encryption Algorithm (DEA)
3DES
Rijndael
International Data Encryption Algorithm (IDEA)
The Data Encryption Standard:
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
Two parties are exchanging messages using public key cryptography. Which of the following statements describes the proper procedure for transmitting an encrypted message?
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
A stream cipher encrypts data by XORing plaintext with the encryption key. How is the ciphertext converted back into plaintext?
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
The purpose of digitally signing a message is to ensure:
Integrity of the sender
Confidentiality of the message
Authenticity of the sender
Confidentiality of the sender
Integrity of the message
The purpose of the Diffie-Hellman key exchange protocol is:
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
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:
Ciphertext only attack
Chosen ciphertext attack
Chosen plaintext attack
Man in the middle attack
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:
Digital signatures
Encryption and digital signatures
Key exchange
