Write an encryption program that reads from cin (a file)and writes the encoded characters to cout (a file). You might use this simple encryption scheme: the encrypted form of a character c is c^key[i] , where key is a string passed as a command-line argument. The program uses the characters in key in a cyclic manner until all the input has been read. Re-encrypting encoded text with the same key produces the original text. If no key (or a null string) is passed, then no encrption is done.