Another new Python 3.6 feature is the addition of the secrets module, a replacement for random when generating cryptographically strong random numbers.

When creating random numbers for with passwords or encryption, the secret module will offer the most secure source of randomness that your operating system can provide.

The secrets module is broken into two sections, random numbers and generating tokens.

Random Numbers

class secrets.SystemRandom
secrets.choice(sequence)
secrets.randbelow(n)
secrets.randbits(k)

Generating Tokens

secrets.token_bytes([nbytes=None])
token_hex([nbytes=None])
token_urlsafe([nbytes=None])

I'm not going to go into the use of these as this is more to bring awareness of the availability of the module than a complete tutorial on cryptography.

I will talk about the two most common parts of the module that will be most interesting to most.

class secrets.SystemRandom

The class SystemRandom offers the most secure known way of generating random numbers for the platform you are using.

Using secrets.SystemRandom is similar to using the random module.

import secrets
rnd = secrets.SystemRandom()
rnd.random()

You want to make sure you call SystemRandom class from secrets module as the random module also has a SystemRandom.

secrets.choice(sequence)

The last part of the module I will go over is the choice method. This method securely returns a random element from a sequence. This is useful when automatically generating random alphanumeric passwords or any random sequence based on an existing sequence.

import secrets
import string
alphanumeric = string.ascii_letters + string.digits
secrets.choice(alphanumeric)

This will return a random letter/numeric from the sequence alphanumeric which consists of all US alphabet characters (upper and lower) and the numbers 0-9.