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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.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.
"""
@abc.abstractproperty
def block_size(self):
"""
The internal block size of the hash algorithm 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.
"""
@utils.register_interface(HashContext)
class Hash(object):
def __init__(self, algorithm, backend, ctx=None):
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.")
if not isinstance(data, bytes):
raise TypeError("data must be bytes.")
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 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 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 > self._max_digest_size or
digest_size < self._min_digest_size
):
raise ValueError("Digest size must be {0}-{1}".format(
self._min_digest_size, self._max_digest_size)
)
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 > self._max_digest_size or
digest_size < self._min_digest_size
):
raise ValueError("Digest size must be {0}-{1}".format(
self._min_digest_size, self._max_digest_size)
)
self._digest_size = digest_size
digest_size = utils.read_only_property("_digest_size")
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