Skip to content
Switch branches/tags

Name already in use

A tag already exists with the provided branch name. Many Git commands accept both tag and branch names, so creating this branch may cause unexpected behavior. Are you sure you want to create this branch?
Go to file
Cannot retrieve contributors at this time
Django's standard crypto functions and utilities.
import hashlib
import hmac
import secrets
from django.conf import settings
from django.utils.encoding import force_bytes
class InvalidAlgorithm(ValueError):
"""Algorithm is not supported by hashlib."""
def salted_hmac(key_salt, value, secret=None, *, algorithm="sha1"):
Return the HMAC of 'value', using a key generated from key_salt and a
secret (which defaults to settings.SECRET_KEY). Default algorithm is SHA1,
but any algorithm name supported by hashlib can be passed.
A different key_salt should be passed in for every application of HMAC.
if secret is None:
secret = settings.SECRET_KEY
key_salt = force_bytes(key_salt)
secret = force_bytes(secret)
hasher = getattr(hashlib, algorithm)
except AttributeError as e:
raise InvalidAlgorithm(
"%r is not an algorithm accepted by the hashlib module." % algorithm
) from e
# We need to generate a derived key from our base key. We can do this by
# passing the key_salt and our base key through a pseudo-random function.
key = hasher(key_salt + secret).digest()
# If len(key_salt + secret) > block size of the hash algorithm, the above
# line is redundant and could be replaced by key = key_salt + secret, since
# the hmac module does the same thing for keys longer than the block size.
# However, we need to ensure that we *always* do this.
return, msg=force_bytes(value), digestmod=hasher)
RANDOM_STRING_CHARS = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
def get_random_string(length, allowed_chars=RANDOM_STRING_CHARS):
Return a securely generated random string.
The bit length of the returned value can be calculated with the formula:
For example, with default `allowed_chars` (26+26+10), this gives:
* length: 12, bit length =~ 71 bits
* length: 22, bit length =~ 131 bits
return "".join(secrets.choice(allowed_chars) for i in range(length))
def constant_time_compare(val1, val2):
"""Return True if the two strings are equal, False otherwise."""
return secrets.compare_digest(force_bytes(val1), force_bytes(val2))
def pbkdf2(password, salt, iterations, dklen=0, digest=None):
"""Return the hash of password using pbkdf2."""
if digest is None:
digest = hashlib.sha256
dklen = dklen or None
password = force_bytes(password)
salt = force_bytes(salt)
return hashlib.pbkdf2_hmac(digest().name, password, salt, iterations, dklen)