o write a C program to encrypt and decrypt text files. Your program (encrypt decrypt) will take four arguments: a key (key), mode keyword (ENCRYPT/DECRYPT), and two text files, an and . If the keyword is ENCRYPT the program should read the first text file (plaintext) and produce an encrypted text file (cyphertext). Conversely, if the keyword is DECRYPT, the first file is an encrypted file (cyphertext), and the output should be a decrypted text file (plaintext)