Merge pull request #2582 from alex/stdlib-pbkdf2hmac

    return binascii.unhexlify((hex_format_string % x).encode('ascii'))

if hasattr(hashlib, "pbkdf2_hmac"):

    def pbkdf2(password, salt, iterations, dklen=0, digest=None):

        """

        Implements PBKDF2 with the same API as Django's existing

        implementation, using the stdlib.

        This is used in Python 3.4 and up.

        """

        if digest is None:

            digest = hashlib.sha256

        if not dklen:

            dklen = None

        password = force_bytes(password)

        salt = force_bytes(salt)

        return hashlib.pbkdf2_hmac(

            digest().name, password, salt, iterations, dklen)

else:

    def pbkdf2(password, salt, iterations, dklen=0, digest=None):

        """

        Implements PBKDF2 as defined in RFC 2898, section 5.2