$2.$ We received the following ciphertext which was encoded with a shift cipher: Xultpaajcxitltlxaarpjhtiwtgxktghidhipxciwtvgtpilpit ghlxiwiwtxgqadds.

a$.$ Perform an attack against the cipher based on a letter frequency count: How many letters do you have to identify through a frequency count to recover the key? What is the cleartext?

b$.$ Who wrote this message?

c$.$ We consider the long$-$term security of the Advanced Encryption Standard $($AES$)$ with a key length of $128-$bit with respect to exhaustive key$-$search attacks. AES is perhaps the most widely used symmetric cipher at this time