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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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