One Time Pad (OTP) encryption, when implemented properly, cannot be hacked by cryptanalysis. This method uses the clear text (message to be encrypted), a random key of characters (the same size of the clear text) and the exclusive OR (XOR) operator. Write a C program with the following functions:

1. main function with a menu including 3 choices: encrypt file, decrypt file and exit program.

2. make_rand_key(length of key, key) generates a fixed length string of random chars.

3. encrypt(clear file, key file, cipher file) generates a random key using make_rand_key(), perform the clear text XOR ket text, byte-by-byte, to produce the cipher text string and write both the random key and cipher text strings to file.

4. decrypt(key file, cipher file, clear file) uses the cipher text XOR random key to recover the original clear text and writes the clear text to a file (make sure to use a different file name than the original file so you can compare the results).

Modify the read_file() and write_file() functions to also accept an integer argument representing a fixed number of bytes to be read or written. This is to specify the number of bytes to be read from the cipher file, which may contain the EOF character, or write to the cipher text file, which may contain null chars. This is necessary because the cipher may contain both EOF and \0 characters. This will be explained further below. Sample function calls to read_file() and write_file():

1. read_file(0, clear_file); // Read in a file with of unknown length, getting the length from the file read. clear_file is a string containing the path to the clear text file. This function returns a char array created with memory allocation.

2. read_file(len, clear_file); // Where len > zero, reads len chars from a file. clear_file is a string containing the path to the clear text file. This function returns a char array created with memory allocation.

3. write_file(0, key, key_file); // Writes a string to file until the \0 char is reached. key is the string of random chars and key_file is a string containing the path of the text file.

4. write_file(len, cipher, cipher_file); // Where len > zero, writes len chars to a file. cipher is the cipher string of chars and cipher_file is a string containing the path of the text file.

The menu in main() should look like:

Encrypt a file: 1

Decrypt a file: 2

Exit: 3

Enter a choice: