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# This file is dual licensed under the terms of the Apache License, Version
# 2.0, and the BSD License. See the LICENSE file in the root of this repository
# for complete details.
from __future__ import absolute_import, division, print_function
import abc
import six
from cryptography import utils
from cryptography.exceptions import (
AlreadyFinalized,
UnsupportedAlgorithm,
_Reasons,
)
from cryptography.hazmat.backends import _get_backend
from cryptography.hazmat.backends.interfaces import HashBackend
@six.add_metaclass(abc.ABCMeta)
class HashAlgorithm(object):
@abc.abstractproperty
def name(self):
"""
A string naming this algorithm (e.g. "sha256", "md5").
"""
@abc.abstractproperty
def digest_size(self):
"""
The size of the resulting digest in bytes.
"""
@six.add_metaclass(abc.ABCMeta)
class HashContext(object):
@abc.abstractproperty
def algorithm(self):
"""
A HashAlgorithm that will be used by this context.
"""
@abc.abstractmethod
def update(self, data):
"""
Processes the provided bytes through the hash.
"""
@abc.abstractmethod
def finalize(self):
"""
Finalizes the hash context and returns the hash digest as bytes.
"""
@abc.abstractmethod
def copy(self):
"""
Return a HashContext that is a copy of the current context.
"""
@six.add_metaclass(abc.ABCMeta)
class ExtendableOutputFunction(object):
"""
An interface for extendable output functions.
"""
@utils.register_interface(HashContext)
class Hash(object):
def __init__(self, algorithm, backend=None, ctx=None):
backend = _get_backend(backend)
if not isinstance(backend, HashBackend):
raise UnsupportedAlgorithm(
"Backend object does not implement HashBackend.",
_Reasons.BACKEND_MISSING_INTERFACE,
)
if not isinstance(algorithm, HashAlgorithm):
raise TypeError("Expected instance of hashes.HashAlgorithm.")
self._algorithm = algorithm
self._backend = backend
if ctx is None:
self._ctx = self._backend.create_hash_ctx(self.algorithm)
else:
self._ctx = ctx
algorithm = utils.read_only_property("_algorithm")
def update(self, data):
if self._ctx is None:
raise AlreadyFinalized("Context was already finalized.")
utils._check_byteslike("data", data)
self._ctx.update(data)
def copy(self):
if self._ctx is None:
raise AlreadyFinalized("Context was already finalized.")
return Hash(
self.algorithm, backend=self._backend, ctx=self._ctx.copy()
)
def finalize(self):
if self._ctx is None:
raise AlreadyFinalized("Context was already finalized.")
digest = self._ctx.finalize()
self._ctx = None
return digest
@utils.register_interface(HashAlgorithm)
class SHA1(object):
name = "sha1"
digest_size = 20
block_size = 64
@utils.register_interface(HashAlgorithm)
class SHA512_224(object): # noqa: N801
name = "sha512-224"
digest_size = 28
block_size = 128
@utils.register_interface(HashAlgorithm)
class SHA512_256(object): # noqa: N801
name = "sha512-256"
digest_size = 32
block_size = 128
@utils.register_interface(HashAlgorithm)
class SHA224(object):
name = "sha224"
digest_size = 28
block_size = 64
@utils.register_interface(HashAlgorithm)
class SHA256(object):
name = "sha256"
digest_size = 32
block_size = 64
@utils.register_interface(HashAlgorithm)
class SHA384(object):
name = "sha384"
digest_size = 48
block_size = 128
@utils.register_interface(HashAlgorithm)
class SHA512(object):
name = "sha512"
digest_size = 64
block_size = 128
@utils.register_interface(HashAlgorithm)
class SHA3_224(object): # noqa: N801
name = "sha3-224"
digest_size = 28
@utils.register_interface(HashAlgorithm)
class SHA3_256(object): # noqa: N801
name = "sha3-256"
digest_size = 32
@utils.register_interface(HashAlgorithm)
class SHA3_384(object): # noqa: N801
name = "sha3-384"
digest_size = 48
@utils.register_interface(HashAlgorithm)
class SHA3_512(object): # noqa: N801
name = "sha3-512"
digest_size = 64
@utils.register_interface(HashAlgorithm)
@utils.register_interface(ExtendableOutputFunction)
class SHAKE128(object):
name = "shake128"
def __init__(self, digest_size):
if not isinstance(digest_size, six.integer_types):
raise TypeError("digest_size must be an integer")
if digest_size < 1:
raise ValueError("digest_size must be a positive integer")
self._digest_size = digest_size
digest_size = utils.read_only_property("_digest_size")
@utils.register_interface(HashAlgorithm)
@utils.register_interface(ExtendableOutputFunction)
class SHAKE256(object):
name = "shake256"
def __init__(self, digest_size):
if not isinstance(digest_size, six.integer_types):
raise TypeError("digest_size must be an integer")
if digest_size < 1:
raise ValueError("digest_size must be a positive integer")
self._digest_size = digest_size
digest_size = utils.read_only_property("_digest_size")
@utils.register_interface(HashAlgorithm)
class MD5(object):
name = "md5"
digest_size = 16
block_size = 64
@utils.register_interface(HashAlgorithm)
class BLAKE2b(object):
name = "blake2b"
_max_digest_size = 64
_min_digest_size = 1
block_size = 128
def __init__(self, digest_size):
if digest_size != 64:
raise ValueError("Digest size must be 64")
self._digest_size = digest_size
digest_size = utils.read_only_property("_digest_size")
@utils.register_interface(HashAlgorithm)
class BLAKE2s(object):
name = "blake2s"
block_size = 64
_max_digest_size = 32
_min_digest_size = 1
def __init__(self, digest_size):
if digest_size != 32:
raise ValueError("Digest size must be 32")
self._digest_size = digest_size
digest_size = utils.read_only_property("_digest_size")