One way to use an affine cipher to make a block cipher is to interpret each vector (21, ...,xn) in Zm as the digits of a number written in the base m, and then consider that number to be an element of Zmn. In the case m = 10, this is just the usual way we interpret a number in base 10. For example, the vector (2,7,1) in Zo would be interpreted as the number 2 . 102 + 7.10+1 = 271 Z1000. And when m = 26 we can interpret blocks of length n = 2 as elements of Z262 Z676 as follows: (21, x2) Z26 4+ 26x1 + x2 Z676. Then given a, b E Z676 we can use the affine function y= e(x) = ax + b on Z676 to effectively encrypt the block of length 2. Suppose that such an encryption scheme is used (where m = 26 and n= 2) with a = 115 and b=314. (a) Encrypt the word SAVE (in blocks of length 2). (b) Use the extended Euclidean algorithm to find a-1 in Z676 and the decryption function =d(y). One way to use an affine cipher to make a block cipher is to interpret each vector (21, ...,xn) in Zm as the digits of a number written in the base m, and then consider that number to be an element of Zmn. In the case m = 10, this is just the usual way we interpret a number in base 10. For example, the vector (2,7,1) in Zo would be interpreted as the number 2 . 102 + 7.10+1 = 271 Z1000. And when m = 26 we can interpret blocks of length n = 2 as elements of Z262 Z676 as follows: (21, x2) Z26 4+ 26x1 + x2 Z676. Then given a, b E Z676 we can use the affine function y= e(x) = ax + b on Z676 to effectively encrypt the block of length 2. Suppose that such an encryption scheme is used (where m = 26 and n= 2) with a = 115 and b=314. (a) Encrypt the word SAVE (in blocks of length 2). (b) Use the extended Euclidean algorithm to find a-1 in Z676 and the decryption function =d(y)