Secure Password Hashing in Python

Learn how to securely hash passwords in Python

Posted July 1, 2022

The password hashing function to use is argon2id

Skip to the end to view the full code.

To get started in Python, create a virtual environment.

$ python -m venv venv

Activate the virtual environment in the current shell

# linux:
$ source ./venv/bin/activate
# windows
$ ./venv/scripts/activate

Install PyNaCl which is a Python library that binds to libsodium

$ pip install pynacl

The code

Import the argon2id class

from nacl.pwhash import argon2id

Create the hash of the password

password = "extremelysecretpassword".encode("utf-8") # password must be bytes, cannot be a string
hashed_password = argon2id.str(password) # returns bytes, good idea to store it in a bytes column in a database

Next, we take the hashed password and we verify it.

is_valid = argon2id.verify(hashed_password, password)

Calling verify with improper credentials will raise nacl.exceptions.InvalidkeyError. You can use a try/except block to capture this and send an error back to your user. Finally, we can then print the result.


Full Code

from nacl.pwhash import argon2id

password = "extremelysecretpassword".encode("utf-8")
hashed_password = argon2id.str(password)

is_valid = argon2id.verify(hashed_password, password)



$ python

PyNaCl argon2id documentation: