Encryption and Decryption Script

This script provides a command-line interface for encrypting and decrypting messages using the AES-256-CBC encryption algorithm. It aims to facilitate the process of writing down encrypted messages on paper for secure communication.

Usage:

$ ./script.sh -e|--encrypt <password> [<msg>]   Encrypt a message.
$ ./script.sh -d|--decrypt <password> [<msg>]   Decrypt a message.
$ ./script.sh -h|--help                         Display this help message.
$ ./script.sh -v|--version                      Display the version number.

Options:

- `-p|--paper-writable`: Formats the output for handwriting (default). This option breaks the encrypted message into four-digit chunks and numbers them, making it easier to transcribe onto paper.
- `-m|--machine`: Outputs the result without formatting.
- `--base36`: Use base36 instead hexadecimal to save space.
- `--`: To separate the message in case it starts with '-'.

Examples:

1. Encrypt a message:
   $ echo "This is a message" | ./script.sh -e mypassword

2. Decrypt an encrypted message:
   $ echo "53616c7465645f..." | ./script.sh -d mypassword

3. Encrypt a message containing special characters:
   $ ./script.sh -e mypassword -- -a

Feel free to use and modify this script according to your requirements.