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213 lines
6.9 KiB
213 lines
6.9 KiB
from __future__ import absolute_import, division, print_function
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import os
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from ._utils import Parameters, _check_types, extract_parameters
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from .exceptions import InvalidHash
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from .low_level import Type, hash_secret, verify_secret
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DEFAULT_RANDOM_SALT_LENGTH = 16
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DEFAULT_HASH_LENGTH = 16
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DEFAULT_TIME_COST = 2
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DEFAULT_MEMORY_COST = 102400
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DEFAULT_PARALLELISM = 8
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def _ensure_bytes(s, encoding):
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"""
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Ensure *s* is a bytes string. Encode using *encoding* if it isn't.
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"""
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if isinstance(s, bytes):
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return s
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return s.encode(encoding)
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class PasswordHasher(object):
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r"""
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High level class to hash passwords with sensible defaults.
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Uses Argon2\ **id** by default and always uses a random salt_ for hashing.
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But it can verify any type of Argon2 as long as the hash is correctly
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encoded.
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The reason for this being a class is both for convenience to carry
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parameters and to verify the parameters only *once*. Any unnecessary
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slowdown when hashing is a tangible advantage for a brute force attacker.
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:param int time_cost: Defines the amount of computation realized and
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therefore the execution time, given in number of iterations.
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:param int memory_cost: Defines the memory usage, given in kibibytes_.
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:param int parallelism: Defines the number of parallel threads (*changes*
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the resulting hash value).
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:param int hash_len: Length of the hash in bytes.
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:param int salt_len: Length of random salt to be generated for each
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password.
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:param str encoding: The Argon2 C library expects bytes. So if
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:meth:`hash` or :meth:`verify` are passed an unicode string, it will be
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encoded using this encoding.
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:param Type type: Argon2 type to use. Only change for interoperability
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with legacy systems.
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.. versionadded:: 16.0.0
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.. versionchanged:: 18.2.0
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Switch from Argon2i to Argon2id based on the recommendation by the
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current RFC_ draft.
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.. versionchanged:: 18.2.0
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Changed default *memory_cost* to 100 MiB and default *parallelism* to 8.
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.. versionchanged:: 18.2.0 ``verify`` now will determine the type of hash.
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.. versionchanged:: 18.3.0 The Argon2 type is configurable now.
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.. _salt: https://en.wikipedia.org/wiki/Salt_(cryptography)
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.. _kibibytes: https://en.wikipedia.org/wiki/Binary_prefix#kibi
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.. _RFC: https://tools.ietf.org/html/draft-irtf-cfrg-argon2-04#section-4
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"""
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__slots__ = ["_parameters", "encoding"]
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def __init__(
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self,
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time_cost=DEFAULT_TIME_COST,
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memory_cost=DEFAULT_MEMORY_COST,
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parallelism=DEFAULT_PARALLELISM,
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hash_len=DEFAULT_HASH_LENGTH,
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salt_len=DEFAULT_RANDOM_SALT_LENGTH,
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encoding="utf-8",
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type=Type.ID,
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):
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e = _check_types(
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time_cost=(time_cost, int),
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memory_cost=(memory_cost, int),
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parallelism=(parallelism, int),
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hash_len=(hash_len, int),
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salt_len=(salt_len, int),
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encoding=(encoding, str),
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type=(type, Type),
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)
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if e:
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raise TypeError(e)
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# Cache a Parameters object for check_needs_rehash.
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self._parameters = Parameters(
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type=type,
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version=19,
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salt_len=salt_len,
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hash_len=hash_len,
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time_cost=time_cost,
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memory_cost=memory_cost,
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parallelism=parallelism,
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)
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self.encoding = encoding
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@property
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def time_cost(self):
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return self._parameters.time_cost
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@property
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def memory_cost(self):
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return self._parameters.memory_cost
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@property
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def parallelism(self):
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return self._parameters.parallelism
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@property
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def hash_len(self):
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return self._parameters.hash_len
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@property
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def salt_len(self):
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return self._parameters.salt_len
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@property
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def type(self):
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return self._parameters.type
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def hash(self, password):
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"""
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Hash *password* and return an encoded hash.
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:param password: Password to hash.
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:type password: ``bytes`` or ``unicode``
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:raises argon2.exceptions.HashingError: If hashing fails.
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:rtype: unicode
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"""
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return hash_secret(
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secret=_ensure_bytes(password, self.encoding),
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salt=os.urandom(self.salt_len),
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time_cost=self.time_cost,
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memory_cost=self.memory_cost,
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parallelism=self.parallelism,
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hash_len=self.hash_len,
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type=self.type,
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).decode("ascii")
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_header_to_type = {
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b"$argon2i$": Type.I,
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b"$argon2d$": Type.D,
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b"$argon2id": Type.ID,
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}
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def verify(self, hash, password):
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"""
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Verify that *password* matches *hash*.
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.. warning::
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It is assumed that the caller is in full control of the hash. No
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other parsing than the determination of the hash type is done by
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``argon2-cffi``.
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:param hash: An encoded hash as returned from
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:meth:`PasswordHasher.hash`.
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:type hash: ``bytes`` or ``unicode``
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:param password: The password to verify.
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:type password: ``bytes`` or ``unicode``
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:raises argon2.exceptions.VerifyMismatchError: If verification fails
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because *hash* is not valid for *password*.
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:raises argon2.exceptions.VerificationError: If verification fails for
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other reasons.
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:raises argon2.exceptions.InvalidHash: If *hash* is so clearly
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invalid, that it couldn't be passed to Argon2.
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:return: ``True`` on success, raise
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:exc:`~argon2.exceptions.VerificationError` otherwise.
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:rtype: bool
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.. versionchanged:: 16.1.0
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Raise :exc:`~argon2.exceptions.VerifyMismatchError` on mismatches
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instead of its more generic superclass.
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.. versionadded:: 18.2.0 Hash type agility.
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"""
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hash = _ensure_bytes(hash, "ascii")
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try:
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hash_type = self._header_to_type[hash[:9]]
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except (IndexError, KeyError, LookupError):
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raise InvalidHash()
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return verify_secret(
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hash, _ensure_bytes(password, self.encoding), hash_type
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)
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def check_needs_rehash(self, hash):
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"""
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Check whether *hash* was created using the instance's parameters.
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Whenever your Argon2 parameters -- or ``argon2-cffi``'s defaults! --
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change, you should rehash your passwords at the next opportunity. The
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common approach is to do that whenever a user logs in, since that
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should be the only time when you have access to the cleartext
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password.
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Therefore it's best practice to check -- and if necessary rehash --
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passwords after each successful authentication.
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:rtype: bool
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.. versionadded:: 18.2.0
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"""
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return self._parameters != extract_parameters(hash)
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