Part A. Pick a plaintext message (10 letters, first letter same as your name's, for example: ASSOCIATED since my name, Anna, starts with A): AFFILIATED (in upper case) Now, we will examine some massage digest functions suitable for storing strings of characters. Make a message digest by using "Sum of ASCII values" of the letters in your plaintext string, and then modulo131 to get the message digest: Create a message digest by using sum of ASCII, then modulo 131 to get the MD= As with many other massage digest functions, the final step is to apply the modulus operator to the result. Because the ASCII value for "A" is 65 and "Z" is 90, sum will always be in the range 650 to 900 for a string of ten upper case letters. Create a MAC: encrypt the MD using 3D modist to get MAC = . You receive FIVEBIGPIGS with MAC-70. Following the same steps as above, explain if this is a valid message. Following the same step as above explain if SIXBIGPIGS with MAC-73 is valid.