5. The Vigenere Cipher: This problem explores the use of a one-time pad version of the Vigenere cipher. In this scheme the key is a stream of random numbers between 0 and 26. Foe example if the key is 3 19 5... then the first letter of the plaintext is encrypted with a shift of 3 letters, the second with a shift of 19 letters, the third with a shift of 5 letters and so on a. Encrypt the plaintext sendmoremoney with the keystream 901723 15 21 14 11 11 2 8 9 b. Using the ciphertext obtained in part a above, find a key so that the cipher decrypts to the plaintext cashnotneeded