VeraCrypt Header Shredder

import os
import tkinter as tk
from tkinter import filedialog, messagebox, simpledialog

def overwrite_file_edges(file_path):
    """Overwrite the first and last 131072 bytes of the specified file after creating a backup."""
    overwrite_size = 131072  # Size of bytes to overwrite
    total_required_size = 262144  # Total size required to safely overwrite

    if os.path.getsize(file_path) < total_required_size:
        messagebox.showerror("Error", "The file is smaller than 262144 bytes. Please select another file.")
        return False  # Indicate that the operation was unsuccessful due to file size

    try:
        # Create a backup of the first 131072 bytes
        with open(file_path, 'rb') as f:
            original_data_start = f.read(overwrite_size)  # Read the first 131072 bytes

        # Generate random bytes for overwriting
        random_data_start = os.urandom(overwrite_size)
        random_data_end = os.urandom(overwrite_size)

        # Ask the user if they want to save the backup
        backup_file_path = filedialog.asksaveasfilename(defaultextension=".bak",
                                                          filetypes=[("Backup Files", "*.bak"),
                                                                     ("All Files", "*.*")],
                                                          title="Save Backup File")

        if backup_file_path:  # Check if the user selected a file path for the backup
            with open(backup_file_path, 'wb') as backup_file:
                backup_file.write(original_data_start)  # Write the backup

        # Warning message before overwriting
        response = simpledialog.askstring("WARNING",
                                            "YOU ARE ABOUT TO SHRED YOUR VOLUME HEADER.\n"
                                            "Type 'yes' to proceed:")

        if response and response.lower() == "yes":
            # Overwrite the original file
            with open(file_path, 'r+b') as f:
                f.seek(0)  # Move the file pointer to the beginning
                f.write(random_data_start)  # Write random data to the start

                f.seek(-overwrite_size, os.SEEK_END)  # Move to the end minus 131072 bytes
                f.write(random_data_end)  # Write random data to the end

            messagebox.showinfo("Success", "Successfully overwritten the first and last 131072 bytes of the file.")
            return True  # Indicate success
        else:
            messagebox.showinfo("Cancelled", "Overwrite operation cancelled.")
            return False  # Indicate cancellation

    except Exception as e:
        messagebox.showerror("Error", f"An error occurred: {str(e)}")
        return False  # Indicate error

def browse_file():
    """Open a file dialog to select a file and overwrite its edges."""
    while True:  # Loop until a valid file is processed
        file_path = filedialog.askopenfilename()
        if file_path:
            if overwrite_file_edges(file_path):  # If successful overwrite, break the loop
                break  # Exit the loop if file is processed successfully
        else:
            break  # Exit if no file is selected

    # Exit the application after processing
    root.quit()

if __name__ == "__main__":
    # Display initial messages
    print("VeraCrypt Header Shredder")
    print("\nYou will now select the container with the header to shred and the backup location for the original one.")

    # Wait for user input before proceeding
    input("Press Enter to continue...")

    # Set up a simple GUI window
    root = tk.Tk()
    root.title("VeraCrypt Header Shredder")  # Set the window title
    root.withdraw()  # Hide the root window since we only want the file dialog

    # Open the file dialog
    browse_file()