## Briefly define a nonsingular transformation

CHAPTER 4

1. Briefly define a nonsingular transformation.

2. What is the difference between a block cipher and a stream cipher?

3. Why is it not practical to use an arbitrary reversible substitution cipher of the kind shown in Table 4.1?

4. Briefly define the terms substitution and permutation.

5. What is the difference between diffusion and confusion?

6. Which parameters and design choices determine the actual algorithm of a Feistel cipher?

7. What are the critical aspects of Feistel cipher design?

CHAPTER 5

1. Briefly define a group.

2. Briefly define a ring.

3. Briefly define a field.

4. List three classes of polynomial arithmetic.

CHAPTER 6

1. What was the original set of criteria used by NIST to evaluate candidate AES ciphers?

2. What was the final set of criteria used by NIST to evaluate candidate AES ciphers?

3. What is the difference between Rijndael and AES?

4. What is the purpose of the **State **array?

5. How is the S-box constructed?

6. Briefly describe SubBytes.

7. Briefly describe ShiftRows.

8. How many bytes in **State **are affected by ShiftRows?

9. Briefly describe MixColumns.

10. Briefly describe AddRoundKey.

11. Briefly describe the key expansion algorithm.

12. What is the difference between SubBytes and SubWord?

13. What is the difference between ShiftRows and RotWord?

14. What is the difference between the AES decryption algorithm and the equivalent inverse cipher?