
Posted on • Edited on • Originally published atblog.learnhubafrica.org
Build a Python Password Generator: A Beginner's Guide
Having your password generator hosted and serving only you is an amazing tool and a project to start; in this guide, we will explore how to build a simple password generator and host it using Pythonanywhere.
Table of Contents
- Introduction to Password Security
- Setting Up Your Python Environment
- Building the Password Generator
- Understanding the Code
- Enhancing the Password Generator
- Hosting Your Project on PythonAnywhere
- Conclusion## Introduction to Password Security
In an era where data breaches are increasingly common, having strong, unique passwords for each of your online accounts is more important than ever. A strong password typically includes a mix of uppercase and lowercase letters, numbers, and special characters. It should also be long enough to resist brute-force attacks. However, creating and remembering such passwords can be challenging. This is where a password generator comes in handy.
Setting Up Your Python Environment
Before we dive into coding, ensure you have Python installed on your computer. You can download it from theofficial Python website. For this project, we'll be using Python 3.12.7
To check your Python version, open your command prompt or terminal and type:
python --version
If you see a version number starting with 3 (e.g., Python 3.8.5), you're ready to begin.
The Complete Password Generator Code
Let's start by looking at the entire code for our password generator. Don't worry if it looks intimidating; we'll break it down line by line in the next section.
importrandomimportstringdefgenerate_password(length=12):characters=string.ascii_letters+string.digits+string.punctuationpassword=''.join(random.choice(characters)for_inrange(length))returnpassworddefmain():print("Welcome to the Simple Password Generator!")try:length=int(input("Enter the desired password length:"))iflength<=0:raiseValueError("Password length must be positive")exceptValueErrorase:print(f"Invalid input:{e}")print("Using default length of 12 characters.")length=12password=generate_password(length)print(f"\nYour generated password is:{password}")if__name__=="__main__":main()
Now, let's break this down and examine each part in detail, but before that, we can look at this amazing article I wroteBuild An Advanced Password Cracker With Python (Complete Guide)
Importing Necessary Modules
importrandomimportstring
These two lines import the modules we need for our password generator:
The
[random](https://www.w3schools.com/python/module_random.asp)
module provides functions for generating random numbers and making random selections. We'll use it to randomly choose characters for our password.The
[string](https://docs.python.org/3/library/string.html)
module offers constants containing various types of characters (letters, digits, punctuation). This saves us from manually typing out all possible characters we might want in a password.The generate_password Function
defgenerate_password(length=12):
This line defines a function namedgenerate_password
. Thedef
keyword in Python is used to define a function. The function takes one parameter,length
, with a default value of 12. This means if no length is specified when calling the function, it will generate a password of 12 characters.
characters=string.ascii_letters+string.digits+string.punctuation
This line creates a string namedcharacters
that contains all the possible characters we might use in our password. Let's break it down.
string.ascii_letters
contains all ASCII letters, both lowercase (a-z) and uppercase (A-Z).string.digits
contains all decimal digits (0-9).string.punctuation
contains all punctuation characters.
By adding these together with the+
operator, we create a single string containing all these characters.
password=''.join(random.choice(characters)for_inrange(length))
This line is where the actual password generation happens. It's a bit complex, so let's break it down further.
random.choice(characters)
randomly selects one character from ourcharacters
string.for _ in range(length)
creates a loop that runslength
number of times. The underscore_
is used as a throwaway variable name, as we don't need to use the loop variable.- This loop is part of a generator expression that creates an iterator of randomly chosen characters.
''.join(...)
takes this iterator and joins all the characters together into a single string, with an empty string''
between each character.
The result is stored in thepassword
variable.
return password
This line returns the generated password from the function.
The main Function
def main():
This line defines ourmain
function, which will handle user interaction and call ourgenerate_password
function.
print("Welcome to the Simple Password Generator!")
This line prints a welcome message for the user.
try:length=int(input("Enter the desired password length:"))iflength<=0:raiseValueError("Password length must be positive")
These lines are part of atry
block, which allows us to handle potential errors:
- We prompt the user to enter a desired password length and attempt to convert their input to an integer using
int()
. - If the user enters a value less than or equal to 0, we manually raise a
ValueError
with a custom message.
exceptValueErrorase:print(f"Invalid input:{e}")print("Using default length of 12 characters.")length=12
Thisexcept
block catches anyValueError
that might occur, either fromint()
if the user enters a non-numeric value, or from our manually raised error if they enter a non-positive number.
- We print an error message, including the specific error (
e
). - We inform the user that we'll use the default length of 12 characters.
- We set
length
to 12.
password=generate_password(length)print(f"\nYour generated password is:{password}")
These lines call ourgenerate_password
function with the specified (or default) length, and then print the resulting password.
Running the Script
if__name__=="__main__":main()
This block is a common Python idiom. It checks if the script is being run directly (as opposed to being imported as a module). If it is, it calls themain()
function.
Lets explore__
**name__**
=
"
__main__"
Understandingif __name__ == "__main__"
in Python
The lineif __name__ == "__main__":
might look strange if you're new to Python, but it's a very useful and common pattern. Let's break it down step by step:
Cheeks?
This line checks whether the Python script is being run directly by the user or if it's being imported as a module into another script. Based on this, it decides whether to run certain parts of the code or not.
What are__name__
and"__main__"
?
__name__
is a special variable in Python. Python sets this variable automatically for each script that runs.- When you run a Python file directly (like when you type
python your_script.py
in the command line), Python sets__name__
to the string"__main__"
for that script. - However, if your script is imported as a module into another script,
__name__
is set to the name of the script/module.## An analogy to understand this better
Imagine you have a Swiss Army knife. This knife has many tools, like a blade, scissors, and a screwdriver.
- When you use the knife directly, you use it as the "main" tool. This is like running your Python script directly.
- But sometimes, you might just want to use one specific tool from the knife as part of a bigger task. This is like importing your script as a module into another script.
Theif __name__ == "__main__":
check is like the knife asking, "Am I being used as the main tool right now, or am I just lending one of my tools to another task?"
Why is this useful?
This check allows you to write code that can be both run on its own and imported by other scripts without running unintended code. Here's a practical example.
defgreet(name):returnf"Hello,{name}!"defmain():name=input("Enter your name:")print(greet(name))if__name__=="__main__":main()
In this script:
- If you run it directly, it will ask for your name and greet you.
- If you import it into another script, you can use the
greet
function without the script automatically asking for input.## How it works in our password generator
In our password generator script.
if__name__=="__main__":main()
This means:
- If you run the password generator script directly, it will call the
main()
function and start generating passwords. - If you import the script into another Python file, it won't automatically start the password generation process. This allows you to use the
generate_password()
function in other scripts without running the interactive part.
Our password generator works, and in the next part of this article, we will modify the password generator to do a lot more, which includes.
Custom Character Sets: Allow users to specify which types of characters they want in their password (e.g., only letters and numbers, no special characters).
Password Strength Checker: Implement a function to evaluate the strength of the generated password and provide feedback to the user.
Multiple Passwords: Give users the option to generate multiple passwords at once.
GUI Interface: Create a graphical user interface using a library like Tkinter to make the program more user-friendly.
Password Storage: Implement a secure way to store generated passwords, possibly with encryption.
Resource
Top comments(6)

Please don't recommend therandom
module for a password generator.
This is straight from the python documentation:
Thesecrets module is used for generating cryptographically strong random numbers suitable for managing data such as passwords, account authentication, security tokens, and related secrets.
In particular, secrets should be used in preference to the default pseudo-random number generator in the random module, which is designed for modelling and simulation, not security or cryptography.

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I think this is mostly because of the fact that random values are random but the way it generates random numbers isnot random
You can check out
roadmap.sh/guides/random-numbers

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I did not really thought of this, thanks for the article, It explored it better.
I would write a follow up on it.

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Oh, thanks. Why this article is just for the educational use cases? I will put a caveat for users who want to go further to take this advice into consideration.
Thanks a lot.

Enhancing Python's Random Library with Unix Time Seeding
When working with Python'srandom
library, you need to ensure a high degree of randomness, especially for applications requiring strong unpredictability. One effective method to achieve this is by using Unix time as a seed. Here's how you can implement this technique:
Step 1: Import Required Libraries
First, import the necessary libraries:
importrandomimporttime
Step 2: Set the Seed Using Unix Time
Use the current Unix timestamp as the seed for the random number generator:
current_time=int(time.time())random.seed(current_time)
Step 3: Generate Random Numbers
Now you can use any of therandom
library's functions to generate random numbers:
random_number=random.randint(1,100)print(f"Random number:{random_number}")
Why This Works
- Unix time provides a constantly changing value, ensuring a different seed each time your program runs.
- This method increases entropy and reduces the predictability of the random number sequence.
Considerations
- While this method significantly improves randomness, it's not suitable for cryptographic purposes.
- For cryptographically secure random numbers, use Python's
secrets
module instead.
By implementing this technique, you can enhance the randomness of Python's built-in random number generator for most general-purpose applications.

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This is interesting, I am currently rewriting the article using secret but I find using seed to change the entropy quite ingenious.
Thanks for your comment.
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