3. Answer the following questions related to the Data Encryption Standard (DES). (a) What is achieved by combining substitution and permutation? (2 points) (b) Describe one cycle of DES. (Be specific about the operations being involved.)? (4 points) (c) What was the main reason that led to replacing DES with AES? Why AES will not face the same problem as DES? (4 points) (Total 10 points)