Use the Caesar cipher to decrypt the following ciphertext: $(4$ points$)$

WKH RZOV DUH QRW ZKDW WKHB VHHP

Use the Vigen$$re cipher to encrypt the following plaintext using the key PETE: $(4$

points$)($NOT CHAT GPT$)$

THERE WAS A FISH IN THE PERCOLATOR

Use the Vigen$$re cipher to decrypt the following ciphertext using the key LAURA: $(4$

points$)($NOT CHAT GPT$)$

QILV WLLE NIEH GV

The DES block cipher uses a $56-$bit key to encrypt a plaintext message.

$($a$)$ If an operation consists of randomly choosing a possible DES key and testing

if it is correct, how many operations are required to guarantee that the

cipher will be broken? $(3$ points$)$

$($b$)$ If each operation took $2^{-28}$ seconds $($about $3\mathrm{.}7$ nanoseconds$)$ approximately

how many days would it take to perform this attack? $(4$ points$)$

$($c$)$ If this attack were performed in parallel on $128$ processors, approximately

how many days would it take for one of the attacks to succeed? $(3$ points$)$

CSCI $5613$ students only: write a short summary of "Cryptography and Computer

Privacy" $-$ Feistel $(1973).(10$ points$)$

The summary should be around $3$ paragraphs long.

Use your own words. Do not copy and paste sections of the paper or use a

program like ChatGPT to generate the summary for you.

Highlight all of the important points in the paper, and make sure to answer

the following questions:

What is a cipher and what makes a cipher secure$?$

What is the One$-$Time Pad and how could it be made more practical?

What is a block cipher and how does the Lucifer cipher work?