Multile Choice:

1.Which one of the following ciphers requires key synchronization between sender and receiver to communicate?

a. Stream ciphers only.

b. Block ciphers only.

c.Stream ciphers and some block ciphers

d. Neither stream ciphers nor block ciphers

Q2. A message's digital signature is primarily used to:

a. Provide message encryption

b.ask the receiver to respond to the message

c, provide message and entity authentication, but not confidentiality.

d.add redundancy to the message to thwart traffic analysis attack,

Q3. When applying a public one-wat hash function, the purpose of the hashed value is:

a. mesage encryption, so that attckers cannot read the message.\

b.message intergrity, so that attackers cannot modify the message.

c.not useful

d.user identification

Q4. Pretty Good Privacy (PGP) is a package for :

a.local area network security.

b.email system security

c. operating system security

d. commercial encryption standards

Q5. IN Pretty Good Privacy,

a.one can choose to only use a symmetric key cipher, or to only use a public key cipher.

b.the session key is encrypted using receiver's public key.

c.authentication and confidentiality are always performed.

d. only the sending mode has a private key ring