from __future__ import absolute_import, division, print_function import os from ._utils import Parameters, _check_types, extract_parameters from .exceptions import InvalidHash from .low_level import Type, hash_secret, verify_secret DEFAULT_RANDOM_SALT_LENGTH = 16 DEFAULT_HASH_LENGTH = 16 DEFAULT_TIME_COST = 2 DEFAULT_MEMORY_COST = 102400 DEFAULT_PARALLELISM = 8 def _ensure_bytes(s, encoding): """ Ensure *s* is a bytes string. Encode using *encoding* if it isn't. """ if isinstance(s, bytes): return s return s.encode(encoding) class PasswordHasher(object): r""" High level class to hash passwords with sensible defaults. Uses Argon2\ **id** by default and always uses a random salt_ for hashing. But it can verify any type of Argon2 as long as the hash is correctly encoded. The reason for this being a class is both for convenience to carry parameters and to verify the parameters only *once*. Any unnecessary slowdown when hashing is a tangible advantage for a brute force attacker. :param int time_cost: Defines the amount of computation realized and therefore the execution time, given in number of iterations. :param int memory_cost: Defines the memory usage, given in kibibytes_. :param int parallelism: Defines the number of parallel threads (*changes* the resulting hash value). :param int hash_len: Length of the hash in bytes. :param int salt_len: Length of random salt to be generated for each password. :param str encoding: The Argon2 C library expects bytes. So if :meth:`hash` or :meth:`verify` are passed an unicode string, it will be encoded using this encoding. :param Type type: Argon2 type to use. Only change for interoperability with legacy systems. .. versionadded:: 16.0.0 .. versionchanged:: 18.2.0 Switch from Argon2i to Argon2id based on the recommendation by the current RFC_ draft. .. versionchanged:: 18.2.0 Changed default *memory_cost* to 100 MiB and default *parallelism* to 8. .. versionchanged:: 18.2.0 ``verify`` now will determine the type of hash. .. versionchanged:: 18.3.0 The Argon2 type is configurable now. .. _salt: https://en.wikipedia.org/wiki/Salt_(cryptography) .. _kibibytes: https://en.wikipedia.org/wiki/Binary_prefix#kibi .. _RFC: https://tools.ietf.org/html/draft-irtf-cfrg-argon2-03#section-4 """ __slots__ = ["_parameters", "encoding"] def __init__( self, time_cost=DEFAULT_TIME_COST, memory_cost=DEFAULT_MEMORY_COST, parallelism=DEFAULT_PARALLELISM, hash_len=DEFAULT_HASH_LENGTH, salt_len=DEFAULT_RANDOM_SALT_LENGTH, encoding="utf-8", type=Type.ID, ): e = _check_types( time_cost=(time_cost, int), memory_cost=(memory_cost, int), parallelism=(parallelism, int), hash_len=(hash_len, int), salt_len=(salt_len, int), encoding=(encoding, str), type=(type, Type), ) if e: raise TypeError(e) # Cache a Parameters object for check_needs_rehash. self._parameters = Parameters( type=type, version=19, salt_len=salt_len, hash_len=hash_len, time_cost=time_cost, memory_cost=memory_cost, parallelism=parallelism, ) self.encoding = encoding @property def time_cost(self): return self._parameters.time_cost @property def memory_cost(self): return self._parameters.memory_cost @property def parallelism(self): return self._parameters.parallelism @property def hash_len(self): return self._parameters.hash_len @property def salt_len(self): return self._parameters.salt_len @property def type(self): return self._parameters.type def hash(self, password): """ Hash *password* and return an encoded hash. :param password: Password to hash. :type password: ``bytes`` or ``unicode`` :raises argon2.exceptions.HashingError: If hashing fails. :rtype: unicode """ return hash_secret( secret=_ensure_bytes(password, self.encoding), salt=os.urandom(self.salt_len), time_cost=self.time_cost, memory_cost=self.memory_cost, parallelism=self.parallelism, hash_len=self.hash_len, type=self.type, ).decode("ascii") _header_to_type = { b"$argon2i$": Type.I, b"$argon2d$": Type.D, b"$argon2id": Type.ID, } def verify(self, hash, password): """ Verify that *password* matches *hash*. .. warning:: It is assumed that the caller is in full control of the hash. No other parsing than the determination of the hash type is done by ``argon2_cffi``. :param hash: An encoded hash as returned from :meth:`PasswordHasher.hash`. :type hash: ``bytes`` or ``unicode`` :param password: The password to verify. :type password: ``bytes`` or ``unicode`` :raises argon2.exceptions.VerifyMismatchError: If verification fails because *hash* is not valid for *password*. :raises argon2.exceptions.VerificationError: If verification fails for other reasons. :raises argon2.exceptions.InvalidHash: If *hash* is so clearly invalid, that it couldn't be passed to Argon2. :return: ``True`` on success, raise :exc:`~argon2.exceptions.VerificationError` otherwise. :rtype: bool .. versionchanged:: 16.1.0 Raise :exc:`~argon2.exceptions.VerifyMismatchError` on mismatches instead of its more generic superclass. .. versionadded:: 18.2.0 Hash type agility. """ hash = _ensure_bytes(hash, "ascii") try: hash_type = self._header_to_type[hash[:9]] except (IndexError, KeyError, LookupError): raise InvalidHash() return verify_secret( hash, _ensure_bytes(password, self.encoding), hash_type ) def check_needs_rehash(self, hash): """ Check whether *hash* was created using the instance's parameters. Whenever your Argon2 parameters -- or ``argon2_cffi``'s defaults! -- change, you should rehash your passwords at the next opportunity. The common approach is to do that whenever a user logs in, since that should be the only time when you have access to the cleartext password. Therefore it's best practice to check -- and if necessary rehash -- passwords after each successful authentication. :rtype: bool .. versionadded:: 18.2.0 """ return self._parameters != extract_parameters(hash)