Question:

I need some help with the below:

Create a Java (the choice is yours) for file/directory processing according to the following rules.

0 - Exit

1 - Encrypt file (XOR with password)

2 - Decrypt file (XOR with password)

1 - Encrypt file (XOR with password)

This option prompts the user for a password (max 256 bytes long, may contain letters, digits, other characters) and then prompts the user for a filename and encrypts the content of the selected file using that password. The encryption method is very simple: just XOR the password with the file content byte after byte; the password being shorter than the file content, you must repeat the password as needed.

Note1: the user must be prompted for the filename of the encrypted file (containing the ciphertext) as well, otherwise we would need to overwrite the initial file.

Note2: If no directory was selected an error message must be displayed. If the directory does not contain either of the files specified by the user, an error message must be displayed. The filenames do not include any path.

2 - Decrypt file (XOR with password)

This option prompts the user for a password (max 256 bytes long, may contain letters, digits, other characters) and then prompts the user for a filename and decrypts the content of the selected file using that password. The decryption method is very simple: just XOR the password with the file content byte after byte; the password being shorter than the file content, you must repeat the password as needed.

Note1: the user must be prompted for the filename of the decrypted file as well, otherwise we would need to overwrite the initial file.

Note2: it may seem strange that we are using the same operation (XOR) both for encryption and for decryption, but this is how XOR (exclusive OR) works.

Note3: If no directory was selected an error message must be displayed. If the directory does not contain either of the files specified by the user, an error message must be displayed. The filenames do not include any path.

Testing:

1. For encryption, use the following password "Qwertyuiop[123$4$567]"

2. After encrypting the file with the above password, you obtain an encrypted file of the same length; after decrypting that file with the same password you should obtain an exact replica of the file.