Hi, im having trouble with this programming question

Program is done in C

Context:

The Monoalphabetic Cipher

Shuffle (jumble) the letters of the alphabet arbitrarily

Therefore each plaintext letter maps to a different random ciphertext letter or symbol

Hence the cipher key is 26 letters long

Example Mapping

Plain: abcdefghijklmnopqrstuvwxyz

Cipher: DKVQFIBJWPESCXHTMYAUOLRGZN

Plaintext: ifwewishtoreplaceletters

Ciphertext: WIRFRWAJUHYFTSDVFSFUUFYA

Requirements:

Implement the Mono-Alphabet substitution cipher in C for both:

Encryption

Decryption

Ensure to take your plaintext ( or ciphertext) information from a text file of arbitrary length and output the transformation to a text file.

Additionally, allow the option (e or d), plaintext file, and ciphertext file to be passed to your program as command line arguments

Allow the user to enter an encryption (or decryption) key of their choice.

Usage:

Encryption Usage:

MyCipher e plaintext.dat ciphertext.dat

Decryption Usage:

MyCipher d ciphertext.dat plaintext.dat