1.43 (a) Consider the affine cipher with key k = (k1,k2) whose encryption and de- cryption functions are given by da(c) ki . (c-k2) (mod p), Let p = 541 and let the key be k = (34,71). Encrypt the message m = 204. Decrypt the ciphertext c 431 (b) There are many variationsoftransposition cipher. We can form the letters into a rectangle instead of a square, and we can use various patterns to place the letters into the rectangle and to read them back out. Try to decrypt the following ciphertext, in which the letters were placed horizontally into a rectangle of some size and then read off vertically by columns. WHNCE STRHT TEO0H ALBAT DETET SADHE LEELL QSFMU EEEAT VNLRI ATUDR HTEEA (For convenience, we've written the ciphertext in 5 letter blocks, but that doesn't necessarily mean that the rectangle has a side of length 5.) 1.43 (a) Consider the affine cipher with key k = (k1,k2) whose encryption and de- cryption functions are given by da(c) ki . (c-k2) (mod p), Let p = 541 and let the key be k = (34,71). Encrypt the message m = 204. Decrypt the ciphertext c 431 (b) There are many variationsoftransposition cipher. We can form the letters into a rectangle instead of a square, and we can use various patterns to place the letters into the rectangle and to read them back out. Try to decrypt the following ciphertext, in which the letters were placed horizontally into a rectangle of some size and then read off vertically by columns. WHNCE STRHT TEO0H ALBAT DETET SADHE LEELL QSFMU EEEAT VNLRI ATUDR HTEEA (For convenience, we've written the ciphertext in 5 letter blocks, but that doesn't necessarily mean that the rectangle has a side of length 5.)