$1.$ Why is it important to study the Feistel cipher?

$2.$ Explain the concept of the avalanche effect?

$3.$ Summarize the principal block cipher design principles.

$4.$ Present an overview of the Feistel cipher and explain how decryption is the inverse of encryption.

$5.$ Present an overview of Data Encryption Standard $($DES$)$

$6.$ Which Parameter and design choice determine the actual algorithm of a Feistel cipher.

$7.$ Distinguish among groups, rings, and fields.

$8.$ Define finite fields of the form GF$($p$)$

$9.$ Define finite fields of the form GF$(2$n$)$

$10.$ Explain the differences among ordinary polynomial arithmetic, polynomial arithmetic with coefficients in Zp$,$ and modular polynomial arithmetic in GF$(2$n$)$

$11.$ Explain the two different uses of the mod operator.