password_generator.py

import string
import secrets

# --- 1. Core Generator Function ---
def generate_password(length, use_upper=True, use_numbers=True, use_symbols=True):
    """
    Generates a cryptographically secure password based on dynamic user constraints.
    """
    # Start with lowercase letters as the base
    pool = string.ascii_lowercase
    password_chars = []

    # Dynamically build the character pool and guarantee at least one of each requested type
    if use_upper:
        pool += string.ascii_uppercase
        password_chars.append(secrets.choice(string.ascii_uppercase))
        
    if use_numbers:
        pool += string.digits
        password_chars.append(secrets.choice(string.digits))
        
    if use_symbols:
        pool += string.punctuation
        password_chars.append(secrets.choice(string.punctuation))

    # Fill the remaining length of the password from the combined pool
    remaining_length = length - len(password_chars)
    for _ in range(remaining_length):
        password_chars.append(secrets.choice(pool))

    # Shuffle the list so the guaranteed characters aren't always at the beginning
    # secrets.SystemRandom() is the secure version of random.shuffle
    secure_rng = secrets.SystemRandom()
    secure_rng.shuffle(password_chars)

    return "".join(password_chars)

# --- 2. Interactive Application Loop ---
def main():
    print("\n" + "="*50)
    print("🔐 CRYPTOGRAPHICALLY SECURE PASSWORD GENERATOR 🔐")
    print("="*50)
    print("Type 'quit' at any prompt to exit.\n")
    
    while True:
        # 1. Get dynamic length with error handling
        user_input = input("\nEnter desired password length (minimum 8): ")
        if user_input.lower() == 'quit': 
            break
            
        try:
            length = int(user_input)
            if length < 8:
                print("⚠️  For security, passwords should be at least 8 characters long.")
                continue
        except ValueError:
            print("❌ Invalid input. Please enter a whole number.")
            continue

        # 2. Get dynamic constraints
        print("\nCustomize your password complexity (Y/N):")
        
        ans_upper = input("Include UPPERCASE letters? ").lower()
        if ans_upper == 'quit': break
        use_upper = ans_upper in ['y', 'yes', '']
        
        ans_nums = input("Include NUMBERS? ").lower()
        if ans_nums == 'quit': break
        use_numbers = ans_nums in ['y', 'yes', '']
        
        ans_sym = input("Include SYMBOLS (!@#$)? ").lower()
        if ans_sym == 'quit': break
        use_symbols = ans_sym in ['y', 'yes', '']

        # 3. Generate and display
        print("\n" + "-"*40)
        print("GENERATING...")
        
        try:
            final_password = generate_password(length, use_upper, use_numbers, use_symbols)
            print(f"✅ Your Secure Password:  {final_password}")
        except Exception as e:
            print(f"❌ An error occurred: {e}")
            
        print("-" * 40 + "\n")

if __name__ == "__main__":
    main()