Consider the following encryption algorithm based on the DES P-box scheme. The plain text is divided in blocks of 32 characters and then the table given below is used to rearrange the positions of characters from the plain text to the ciphered test. (a) What type of basic encryption is this algorithm? ( 3 points) (b) How would the picks and valleys of the frequency of letters in the cipher text be distributed? (3 points) (c) Compare what is achieved by using substitution versus using permutation, and why it is good to combine them. Explain what is achieved by combining substitution and permutation in DES. (4 points)