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			236 lines
		
	
	
		
			7.7 KiB
		
	
	
	
		
			Python
		
	
	
	
	
	
			
		
		
	
	
			236 lines
		
	
	
		
			7.7 KiB
		
	
	
	
		
			Python
		
	
	
	
	
	
# SPDX-License-Identifier: MIT
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import os
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from typing import Union
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from ._typing import Literal
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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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from .profiles import RFC_9106_LOW_MEMORY
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DEFAULT_RANDOM_SALT_LENGTH = RFC_9106_LOW_MEMORY.salt_len
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DEFAULT_HASH_LENGTH = RFC_9106_LOW_MEMORY.hash_len
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DEFAULT_TIME_COST = RFC_9106_LOW_MEMORY.time_cost
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DEFAULT_MEMORY_COST = RFC_9106_LOW_MEMORY.memory_cost
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DEFAULT_PARALLELISM = RFC_9106_LOW_MEMORY.parallelism
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def _ensure_bytes(s: Union[bytes, str], encoding: str) -> bytes:
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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:
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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 a ``str``, 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. See also :doc:`parameters`.
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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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    .. versionadded:: 21.2.0 :meth:`from_parameters`
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    .. versionchanged:: 21.2.0
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       Changed defaults to :data:`argon2.profiles.RFC_9106_LOW_MEMORY`.
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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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    """
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    __slots__ = ["_parameters", "encoding"]
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    _parameters: Parameters
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    encoding: str
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    def __init__(
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        self,
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        time_cost: int = DEFAULT_TIME_COST,
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        memory_cost: int = DEFAULT_MEMORY_COST,
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        parallelism: int = DEFAULT_PARALLELISM,
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        hash_len: int = DEFAULT_HASH_LENGTH,
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        salt_len: int = DEFAULT_RANDOM_SALT_LENGTH,
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        encoding: str = "utf-8",
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        type: 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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    @classmethod
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    def from_parameters(cls, params: Parameters) -> "PasswordHasher":
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        """
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        Construct a `PasswordHasher` from *params*.
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        .. versionadded:: 21.2.0
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        """
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        ph = cls()
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        ph._parameters = params
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        return ph
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    @property
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    def time_cost(self) -> int:
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        return self._parameters.time_cost
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    @property
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    def memory_cost(self) -> int:
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        return self._parameters.memory_cost
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    @property
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    def parallelism(self) -> int:
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        return self._parameters.parallelism
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    @property
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    def hash_len(self) -> int:
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        return self._parameters.hash_len
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    @property
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    def salt_len(self) -> int:
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        return self._parameters.salt_len
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    @property
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    def type(self) -> Type:
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        return self._parameters.type
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    def hash(self, password: Union[str, bytes]) -> str:
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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 ``str``
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        :raises argon2.exceptions.HashingError: If hashing fails.
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        :rtype: str
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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(
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        self, hash: Union[str, bytes], password: Union[str, bytes]
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    ) -> Literal[True]:
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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 ``str``
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        :param password: The password to verify.
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        :type password: ``bytes`` or ``str``
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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: str) -> bool:
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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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