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Learn how to use Python to create random strings in two different ways, including secure random strings
AI Software Engineer based in London, UK with 6+ years of professional experience developing and releasing software in different programming languages - Hobbyist Technical Writer - Interested in Software Testing, Best Practices, Scalability, Machine Learning/AI, and Python.
Great! Now, I'm gonna have my own password generator!
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In this post, you'll learn how to create a random string in Python using different methods; but, beware! Some of them only work with Python 3.6+.
By the end of this article, you should be able to:
string.ascii_letters, string.digits + string.punctuation characters in Python 3The string module comes with a nice set of constants that we can combine with the random module to create our random string.
string.ascii_letters + string.digits + string.punctuation CharactersBy concatenating string.ascii_letters + string.digits + string.punctuation, we will have our pool of characters that we can pick at random using the random.choices() method. This method returns a k sized list of elements chosen from the population with replacement. In our case, k will be the size of our random string.
>>> import string
>>> string.ascii_letters
'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ'
>>> string.digits
'0123456789'
>>> string.punctuation
'!"#$%&\'()*+,-./:;<=>?@[\\]^_`{|}~'
>>> all_chars = string.ascii_letters + string.digits + string.punctuation
>>> import random
>>> ''.join(random.choices(all_chars, k=10))
'4`<WJ."=$r'
This works well, but there is one limitation: random.choices is available only on Python 3.6+. To make that work in older versions, you'll need to call the random.choice function and iterate over k times.
>>> ''.join((random.choice(all_chars) for _ in range(10)))
'd&6Bx5PX(R'
The previous method works well if all we want is a random string for simple use cases. If what we want is a random string to be used as a password, then we need a more secure method. The reason is that the random module does not use a secure pseudo-number generator.
As an alternative we must resort to the Operating System’s pseudo-random number generator. The good news is that Python can access that using the random.SystemRandom class, which ensures that sequences are not reproducible.
We can re-use the previous example and change just one minor detail.
From: random.choices to random.SystemRandom()
>>> all_chars = string.ascii_letters + string.digits + string.punctuation
>>> import random
>>> ''.join(random.SystemRandom().choices(all_chars, k=10))
'T$WoW.sdQc'
In this post we saw 2 different ways of creating random strings Python. I hope you find it useful.
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See you next time!
This post was originally published at https://miguendes.me