3.3

What type of key or keys are used in symmetric cryptography?
A single key pair
A unique key for each participant
Two unique sets of key pairs
A shared private key
A shared private key
______________ cryptography uses a unique key pair for each participant. This key pair consists of a public key and a private key.
Asymmetric
How many keys are used with symmetric key cryptography? One
Two
Four
Five
one
Which of the following is not true concerning symmetric key cryptography? Each pair of communicating entities requires a unique shared key.
Before communications begin, both parties must exchange the shared secret key.
The key is not shared with other communication partners.
Key management is easy when implemented on a large scale.
Both parties share the same key (which is kept secret).
Key management is easy when implemented on a large scale.
Which of the following can be classified as a “stream cipher”?
Twofish
Blowfish
AES
RC4
RC4
Blowfish, Twofish, and AES are all _______ ciphers.
block
You want to encrypt data on a removable storage device. Which encryption method would you choose to use the strongest method possible?
AES
3DES
SHA1
RSA
AES
SHA1 is a _______algorithm, not an encryption algorithm
hashing
Which of the following algorithms are used in symmetric encryption? (Select three.)
ElGamal
Blowfish
DiffieHellman
3DES
AES
Blowfish
3DES
AES
Which of the following are true of Triple DES (3DES)? (Select two.)
Is used in IPSec
Can easily be broken
Uses a 168bit key
Uses the Rijndael block cipher
Uses 64bit blocks with 128bit keys
Is used in IPSec
Uses a 168bit key
Advanced Encryption Standard (AES) uses the_______ ___________ cipher
Rijndael block
Which of the following are true concerning the Advanced Encryption Standard (AES) symmetric block cipher? (Select two.)
AES uses a variablelength block and key length (128, 192, or 256bit keys).
AES uses the Rijndael block cipher.
AES uses up to 16 rounds of substitution and transposition.
AES uses 8’128 bit keys in steps of 8 bits.
AES uses a variablelength block and key length (128, 192, or 256bit keys).
AES uses the Rijndael block cipher.
Which of the following symmetric block ciphers does not use a variable block length? International Data Encryption Algorithm (IDEA)
Advanced Encryption Standard (AES)
Elliptic Curve (EC)
Ron’s Cipher v5 (RC5)
International Data Encryption Algorithm (IDEA)
Which of the following encryption mechanisms offers the least security because of weak keys?
TwoFish
AES
DES
IDEA
DES (AES (128, 192, 256 bit keys), TwoFish (up to 256 bit keys), and IDEA (128 bit keys) all support stronger keys than that of DES. )
Which version of the Rivest Cipher is a block cipher that supports variable bit length keys and variable bit block sizes? RSA
RC4
RC5
RC2
RC5
He used 32 bit blocks, a 64 bit key, and he only used the selected key once. He moved the key onto a USB hard drive which was stored in a safety deposit box. Bob’s notebook was stolen. Within a few days Bob discovered the contents of his encrypted file on the Internet. What is the primary reason why Bob’s file was opened so quickly?
Too small of a block size
A birthday attack was used
Weak key
The decryption key was used to decrypt the files
Weak key
You are concerned about the strength of your cryptographic keys, so you implement a system that does the following: The initial key is fed into the input of the bcrypt utility on a Linux workstation. The bcrypt utility produces an enhanced key that is 128 bits long.
The resulting enhanced key is much more difficult to crack than the original key. Which kind of encryption mechanism was used in this scenario?
Ephemeral keys
Perfect forward secrecy
Key stretching
DHE Explanation
Key stretching
Which of the following is considered an outofband distribution method for privatekey encryption? Copying the key to a USB drive
Using a key distribution algorithm
Sending a secured email
Using a private fiber network
Copying the key to a USB drive
_________ distribution involves manually distributing the key, such as copying the key to a USB drive and sending it to the other party.
Outofband
_______ distribution can use a key distribution algorithm, such as DiffieHellman, to send the key to the recipient. It can also use asymmetric encryption technology to encrypt the key for distribution.
In-band
Match the symmetric key distribution mechanism on the left with the appropriate description on the right. Each distribution mechanism may be used once, more than once, or not at all. The sender’s key is sent to a recipient using a DiffieHellman key exchange. The sender’s key is copied to a USB drive and handed to the recipient. The sender’s key is sent to the recipient using publickey cryptography. The sender’s key is burned to a CD and handed to the recipient.
Inband distribution
Outofband distribution
Inband distribution
Outofband distribution
some of the more commonly used hashing algorithms include SHA-1, MD5 and RIPEMD usually the-_____bit version
160
Symmetric encryption is well suited for_______encryption of less sensitive data because it is less CPU-intensive than other encryption methods.
bulk
common symmetric cyptography methods include-
block rc 2, rc5 idea des 3des aes blowfish twofish
stream rc4
_______________________embeds a symmetric key into a message before the message is hashed. When the message is received, the recipient’s symmetric key is added back into the message before hashing the message.
Keyed-hash Message Authentication Code (HMAC)