$6\mathrm{.}1$ Caesar Shift Cipher falls within the $($a$)$

methods. Each letter is shifted by $"2".$

$($b$)$ Use the Caesar shift cipher method to decrypt the following text.

Text: cvvcemcvfcyp

$6\mathrm{.}2$ Briefly describe what perfect forward secrecy is$.$

$6\mathrm{.}3$ Block ciphers transform plaintext one block $(\frac{64}{128}\frac{?}{256}$ bits$)$ at a time, while stream ciphers

convert plaintext to ciphertext one byte at a time. Mention three $(3)$ other key features of stream

ciphers that makes it different from block ciphers.

$6\mathrm{.}4$ Complete a boolean exclusive OR $($XOR$)$ operation on the following two Boolean numbers:

$6\mathrm{.}5$ Your friend feels confident that the integrity of any message encrypted with the ephemeral keys

will be intact. How will you respond to your friend about his "feeling".