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import typing
from . import exceptions
from .hashers import HasherProtocol
class PasswordHash:
"""
Represents a password hashing utility.
"""
def __init__(self, hashers: typing.Sequence[HasherProtocol]) -> None:
"""
Args:
hashers: A sequence of hashers to be used for password hashing.
Raises:
AssertionError: If no hashers are specified.
"""
assert len(hashers) > 0, "You must specify at least one hasher."
self.hashers = hashers
self.current_hasher = hashers[0]
@classmethod
def recommended(cls) -> "PasswordHash":
"""
Returns a PasswordHash instance with recommended hashers.
Currently, the hasher is Argon2 with default parameters.
Examples:
>>> password_hash = PasswordHash.recommended()
>>> hash = password_hash.hash("herminetincture")
>>> password_hash.verify(hash, "herminetincture")
True
"""
from .hashers.argon2 import Argon2Hasher
return cls((Argon2Hasher(),))
def hash(
self,
password: typing.Union[str, bytes],
*,
salt: typing.Union[bytes, None] = None,
) -> str:
"""
Hashes a password using the current hasher.
Args:
password: The password to be hashed.
salt: The salt to be used for hashing. Defaults to None.
Returns:
The hashed password.
Examples:
>>> hash = password_hash.hash("herminetincture")
"""
return self.current_hasher.hash(password, salt=salt)
def verify(
self, password: typing.Union[str, bytes], hash: typing.Union[str, bytes]
) -> bool:
"""
Verifies if a password matches a given hash.
Args:
password: The password to be checked.
hash: The hash to be verified.
Returns:
True if the password matches the hash, False otherwise.
Raises:
exceptions.UnknownHashError: If the hash is not recognized by any of the hashers.
Examples:
>>> password_hash.verify("herminetincture", hash)
True
>>> password_hash.verify("INVALID_PASSWORD", hash)
False
"""
for hasher in self.hashers:
if hasher.identify(hash):
return hasher.verify(password, hash)
raise exceptions.UnknownHashError(hash)
def verify_and_update(
self, password: typing.Union[str, bytes], hash: typing.Union[str, bytes]
) -> typing.Tuple[bool, typing.Union[str, None]]:
"""
Verifies if a password matches a given hash and updates the hash if necessary.
Args:
password: The password to be checked.
hash: The hash to be verified.
Returns:
A tuple containing a boolean indicating if the password matches the hash,
and an updated hash if the current hasher or the hash itself needs to be updated.
Raises:
exceptions.UnknownHashError: If the hash is not recognized by any of the hashers.
Examples:
>>> valid, updated_hash = password_hash.verify_and_update("herminetincture", hash)
"""
for hasher in self.hashers:
if hasher.identify(hash):
if not hasher.verify(password, hash):
return False, None
else:
updated_hash: typing.Union[str, None] = None
if hasher != self.current_hasher or hasher.check_needs_rehash(hash):
updated_hash = self.current_hasher.hash(password)
return True, updated_hash
raise exceptions.UnknownHashError(hash)
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