Secure PIN Generation

TL;DR

This guide shows you how to create strong, random PINs using Python. We’ll focus on avoiding predictable patterns and ensuring enough randomness for good cyber security.

Generating Secure PINs with Python

1. Import the necessary libraries: You’ll need the random library to generate random numbers.

   import random

2. Define a function for generating the PIN: This makes your code reusable and easier to understand. We’ll start with a basic version, then improve it.

   def generate_pin(length):
     pin = ''.join(random.choices('0123456789', k=length))
     return pin

3. Set the PIN length: Choose a suitable length for your PINs (e.g., 4, 6, or 8 digits). Longer pins are more secure.

   pin_length = 6

4. Generate the PIN: Call your function to create a new PIN.

   new_pin = generate_pin(pin_length)

5. Improve randomness (important!): The basic random.choices method is often sufficient, but for higher security, use secrets module if available. This uses a more cryptographically secure random number generator.

   import secrets
   
   def generate_pin(length):
     pin = ''.join(secrets.choice('0123456789') for _ in range(length))
     return pin

6. Avoid predictable patterns: While a truly random PIN is best, you can add checks to avoid common sequences (e.g., 1234, repeated digits). This adds complexity but improves security against simple attacks.
   1. Check for repeating digits:

      def has_repeating_digits(pin):
        for i in range(len(pin) - 1):
          if pin[i] == pin[i+1]:
            return True
        return False

   2. Check for simple sequences:

      def has_simple_sequence(pin):
        for i in range(len(pin) - 2):
          if int(pin[i+1]) == int(pin[i]) + 1 and int(pin[i+2]) == int(pin[i+1]) + 1:
            return True
        return False

   3. Re-generate if necessary: If the PIN fails either check, generate a new one.

      def generate_secure_pin(length):
        while True:
          pin = ''.join(secrets.choice('0123456789') for _ in range(length))
          if not has_repeating_digits(pin) and not has_simple_sequence(pin):
            return pin

7. Test your PIN generation: Generate several PINs to verify they meet your criteria.

   for _ in range(5):
     secure_pin = generate_secure_pin(pin_length)
     print(secure_pin)

8. Store PINs securely: Never store PINs in plain text. Use strong hashing algorithms (e.g., bcrypt, Argon2) with salting to protect them.

   This is beyond the scope of this guide but is crucial for cyber security.