CSCI $345-$ Computer & Network Security

mode is typically used for a general$-$purpose block$-$oriented transmission and is useful for high$-$

speed requirements.

A$.$ ECB

B$.$ OFB

C$.$ CFB

D$.$ CTR

Symmetric encryption is also referred to as secret$-$key or single$-$key encryption. True OR False?

The ciphertext$-$only attack is the easiest to defend against. True OR False?

$(1)$

"Each block of $64$ plaintext bits is encoded independently using the same key" is a description of the CBC

$($Cipher Block Chaining$)$ mode of operation. True OR False?

Consider the $3-$ bit block cipher shown in the below table. Suppose the plaintext is $010111010.$

a$.$ Initially assume that $CBC$ is not used. What is the resulting ciphertext?

b$.$ Now suppose that $CBC$ is used with IV $=000.$ What is the resulting ciphertext?

A specific $3-$bit block cipher