[PYTHON] Password generator creation notes

Front frame

I wanted to research and develop something myself, and I was interested in password generation for a long time, so I decided to make it.

Since Python is a short story, I would like to make it easily using the Python library. Please note that the code is dirty because I am an amateur when it comes to development.

Requirements to aim for

――I want to make it a class first, and finally a web application. --You can select the number of characters --You can select the type of characters to include --You can select something like "capital alphabet appears at least once".

First, find out about random numbers

As a major premise of passwords, ** something that cannot be guessed by others ** is recommended, so how to select characters is important. Therefore, we need a mechanism to randomly select characters.

Python has a random module. https://docs.python.org/ja/3/library/random.html#module-random

However, as stated in the official document above, it is only a random value to some extent that can be logically reproduced / guessed, and is not suitable for security purposes.

Therefore, it is recommended to use the secrets module based on the random number source provided by the OS for security purposes. https://docs.python.org/ja/3/library/secrets.html#module-secrets This is it. This is fine.

Moreover, if you look closely, you will find recipes and best practices.

To generate a 10-character password consisting of alphabeds and numbers, including at least one lowercase letter and at least three numbers:

generate_password_best_practice.py

import string
import secrets
alphabet = string.ascii_letters + string.digits
while True:
    password = ''.join(secrets.choice(alphabet) for i in range(10))
    if (any(c.islower() for c in password)
            and any(c.isupper() for c in password)
            and sum(c.isdigit() for c in password) >= 3):
        break

Let's play with this.

Functionize

Take password length as an argument

generate_random.py

import string
import secrets

alphabet = string.ascii_letters + string.digits

def password_generater(password_length):
    while True:
        password = ''.join(secrets.choice(alphabet) for i in range(password_length))
        if (any(c.islower() for c in password) and any(c.isupper() for c in password) and sum(c.isdigit() for c in password) >= 3):
           break
    return password

main.py

import generate_random 

#Password length can be specified by argument
result = generate_random.password_generater(16)

print(result)

When I run it

7g29HnFJItLJoiB7

Yeah, it feels good.

Take the minimum number of occurrences of each character as an argument

generate_random.py

import string
import secrets

alphabet = string.ascii_letters + string.digits

def password_generater(password_length, lower_letters_min=0, upper_letters_min=0, digit_min=0):
    while True:
        password = ''.join(secrets.choice(alphabet) for i in range(password_length))
        if (sum(c.islower() for c in password) >= lower_letters_min and sum(c.isupper() for c in password) >= upper_letters_min  and sum(c.isdigit() for c in password) >= digit_min):
           break
    return password

Since it is set to 0 by default, it is generated once unless otherwise specified.

When I run it

zmoIBPQVU8MI3tJL

It seems that the condition that "at least three numbers appear" in the official recipe has certainly disappeared.

Try to list the arguments

After trying so far, I came up with the idea that it would be more convenient to summarize the number of occurrences in a list when something like "I want to specify only the minimum number of uppercase letters!"

(Currently under construction)