random_password_generator.py

# --------------------------------------------------------------------------
# Random Password Generator
# Generates a strong, random password based on user-defined length and complexity.
# --------------------------------------------------------------------------
import random
import string

def generate_password(length=12, use_letters=True, use_numbers=True, use_symbols=True):
    """
    Generates a secure password based on specified criteria.

    Args:
        length (int): The desired length of the password.
        use_letters (bool): Include upper and lowercase letters.
        use_numbers (bool): Include digits (0-9).
        use_symbols (bool): Include common symbols (!@#$%^&*).

    Returns:
        str: The generated password, or a message if criteria are invalid.
    """
    if not any([use_letters, use_numbers, use_symbols]):
        return "Error: You must select at least one character type."

    if length <= 0:
        return "Error: Password length must be greater than zero."

    # Define the character sets
    characters = ""
    required_chars = [] # Ensures at least one of each selected type is included

    if use_letters:
        letters = string.ascii_letters
        characters += letters
        required_chars.append(random.choice(letters))

    if use_numbers:
        numbers = string.digits
        characters += numbers
        required_chars.append(random.choice(numbers))

    if use_symbols:
        # Common secure symbols
        symbols = "!@#$%^&*()-_+=[]{}|;:,.<>?"
        characters += symbols
        required_chars.append(random.choice(symbols))

    # Calculate remaining length needed for random filler
    remaining_length = length - len(required_chars)

    # Generate random filler characters
    if remaining_length < 0:
        # If the required characters already exceed the desired length
        # This will only happen if the user inputs a very small length (e.g., 2)
        random_filler = []
        password_list = required_chars[:length]
    else:
        random_filler = [random.choice(characters) for _ in range(remaining_length)]
        password_list = required_chars + random_filler

    # Shuffle the list to ensure the required characters aren't always at the start
    random.shuffle(password_list)

    # Join the list of characters to form the final password string
    return "".join(password_list)

def main():
    """
    Main function to handle user interaction for password generation.
    """
    print("\n--- Python Random Password Generator ---")

    # Get password length
    while True:
        try:
            length = int(input("Enter desired password length (e.g., 16): "))
            if length > 0:
                break
            else:
                print("Length must be a positive number.")
        except ValueError:
            print("Invalid input. Please enter a whole number.")

    # Get complexity preferences
    def get_preference(prompt):
        while True:
            choice = input(f"{prompt} (y/n): ").strip().lower()
            if choice in ['y', 'n']:
                return choice == 'y'
            else:
                print("Invalid input. Please enter 'y' for yes or 'n' for no.")

    use_letters = get_preference("Include letters (A-Z, a-z)?")
    use_numbers = get_preference("Include numbers (0-9)?")
    use_symbols = get_preference("Include symbols (!@#$)?")

    print("\nGenerating password...")
    
    # Generate and print the password
    password = generate_password(length, use_letters, use_numbers, use_symbols)
    
    # Check if the result is an error message
    if password.startswith("Error"):
        print(password)
    else:
        print("\n" + "="*40)
        print(f"Generated Password: {password}")
        print("="*40)

if __name__ == "__main__":
    main()