Alice and Bob agree to communicate privately via e-mail using a scheme based on RC4, but they want to avoid using a new secret key for each transmission. Alice and Bob privately agree on a 128-bit key k. To encrypt a message m consisting of a string of bits, the following procedure is used. 1. Choose a random 80-bit value v 2. Generate the ciphertext c = RC4(v || k) ⊕ m 3. Send the bit string (v || c) Suppose Alice uses this procedure to send a message m to Bob. Describe how Bob can recover the message m from (v || c) using k.