Problem 6-3: Let us define a new stream cipher. The cipher is affine, but the keys depend on the position of the character in the plaintext If the plaintext character to be encrypted is in position n, we can find the keys as follows: a). The multiplicative key is the (n mod 12)-th element in Z2 (b). The additive key is the (n mod 26)-th element in Z26 ; Encrypt the message "cryptography is fun" using this new cipher