What is a block cipher? What is the equation to describe a block cipher? What is symmetric key encryption and compare with Public key encryption? Why is a block cipher considered a keyed permutation? What is the most common block cipher currently in use? Explain the "key schedule" Considering the DES algorithm, what Caused it to encounter serious security issues? What are Sub-Bytes? What is the difference in output when considering ShiftRows and MixColumns? What is 3DES? 3DES is the workhorse of which industry and why