How to make a password generator with python.
Tags: python, beginners, project, security
Published: 2021-11-18 09:32:09

In this tutorial we will make a password generator with the secrets module. Why not random module? see the first post in this series to understand.

**So Let's Begin!**

## Problem
- Generate a random password, according to the user input.

## Sub problems
- Get user input
- Create lists for letters etc...
- Loop over lists and make a password.
- Print the password.

## Let's write some code!
- Get user input
Here we will use try/except blocks so that when user types a string we do not get an error.

We will get inputs for number of special characters, small letters, big letters and numbers required for generating the password.

Code:
```python 
try:
        num_of_numbers = int(input("How many numbers should your password have: "))
except ValueError:
        num_of_numbers = int(input("How many numbers should your password have: "))
try:
        num_of_special = int(
        input("How many special characters should your password have: "))
except ValueError:
        num_of_special = int(
        input("How many special characters should your password have: "))
try:
        num_of_small_letters = int(
        input("How many small letters should your password have: "))
except ValueError:
        num_of_small_letters = int(
        input("How many small letters should your password have: "))
try:
        num_of_cap_letters = int(
        input("How many big letters should your password have:  "))
except ValueError:
        num_of_cap_letters = int(
        input("How many big letters should your password have:  "))

```
 ### Create Lists for numbers to choose from. 
- We could hardcode this like:
```python
number_list = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
```
- But this will take us way more time!

- So let's use the string module!

```python
import string
number_list = list(string.digits)
```
But we could just have a string right? then why make it list you will find this out later on in this blog!

Let's do this for everything.
```python
import string

smallLetters = list(string.ascii_lowercase)

bigLetters = list(string.ascii_uppercase)

specialCharacters = list(string.punctuation)

numbers = list(string.digits)

```

So now we can loop over these lists, and make a list!

First let's declare empty variables!

```python
spPart = ""

numPart = ""

smallPart = ""

bigPart = ""
```

Now let's loop over the lists.

```python
    for i in range(1, num_of_numbers + 1):
        randNum = secrets.choice(numbers)
        numPart = numPart + str(randNum)


    for i in range(1, num_of_special + 1):
        randSp = secrets.choice(specialCharacters)
        spPart = spPart + randSp


    for i in range(1, num_of_small_letters + 1):
        randSm = secrets.choice(smallLetters)
        smallPart = smallPart + randSm


    for i in range(1, num_of_cap_letters + 1):
        randBig = secrets.choice(bigLetters)
        bigPart = bigPart + randBig
```

Now let's add the parts to make a password.

```python
password = numPart + spPart + smallPart + bigPart
```
Now let's refactor the code, by putting this into a function.

```python 

def generate_password( num_of_numbers, num_of_special, num_of_small_letters, num_of_cap_letters):

    smallLetters = list(string.ascii_lowercase)

    bigLetters = list(string.ascii_uppercase)

    specialCharacters = list(string.punctuation)

    numbers = list(string.digits)

    spPart = ""

    numPart = ""

    smallPart = ""

    bigPart = ""
    
    # ANCHOR: Generating Password
    for i in range(1, num_of_numbers + 1):
        randNum = secrets.choice(numbers)
        numPart = numPart + str(randNum)


    for i in range(1, num_of_special + 1):
        randSp = secrets.choice(specialCharacters)
        spPart = spPart + randSp


    for i in range(1, num_of_small_letters + 1):
        randSm = secrets.choice(smallLetters)
        smallPart = smallPart + randSm


    for i in range(1, num_of_cap_letters + 1):
        randBig = secrets.choice(bigLetters)
        bigPart = bigPart + randBig

    password = numPart + spPart + smallPart + bigPart
    
    return password
```
Now if we print/generate the password every time ,there is a predictable format, first numbers then special etc..

So how we can solve this?

We will solve this in the next short blog coming very quickly after this blog, so stay tuned!

***Happy Coding!***