CasperSecurity
# 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.
import abc
import typing
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
class HashAlgorithm(metaclass=abc.ABCMeta):
@abc.abstractproperty
def name(self) -> str:
"""
A string naming this algorithm (e.g. "sha256", "md5").
"""
@abc.abstractproperty
def digest_size(self) -> int:
"""
The size of the resulting digest in bytes.
"""
@abc.abstractproperty
def block_size(self) -> typing.Optional[int]:
"""
The internal block size of the hash function, or None if the hash
function does not use blocks internally (e.g. SHA3).
"""
class HashContext(metaclass=abc.ABCMeta):
@abc.abstractproperty
def algorithm(self) -> HashAlgorithm:
"""
A HashAlgorithm that will be used by this context.
"""
@abc.abstractmethod
def update(self, data: bytes) -> None:
"""
Processes the provided bytes through the hash.
"""
@abc.abstractmethod
def finalize(self) -> bytes:
"""
Finalizes the hash context and returns the hash digest as bytes.
"""
@abc.abstractmethod
def copy(self) -> "HashContext":
"""
Return a HashContext that is a copy of the current context.
"""
class ExtendableOutputFunction(metaclass=abc.ABCMeta):
"""
An interface for extendable output functions.
"""
class Hash(HashContext):
def __init__(self, algorithm: HashAlgorithm, 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: bytes) -> None:
if self._ctx is None:
raise AlreadyFinalized("Context was already finalized.")
utils._check_byteslike("data", data)
self._ctx.update(data)
def copy(self) -> "Hash":
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) -> bytes:
if self._ctx is None:
raise AlreadyFinalized("Context was already finalized.")
digest = self._ctx.finalize()
self._ctx = None
return digest
class SHA1(HashAlgorithm):
name = "sha1"
digest_size = 20
block_size = 64
class SHA512_224(HashAlgorithm): # noqa: N801
name = "sha512-224"
digest_size = 28
block_size = 128
class SHA512_256(HashAlgorithm): # noqa: N801
name = "sha512-256"
digest_size = 32
block_size = 128
class SHA224(HashAlgorithm):
name = "sha224"
digest_size = 28
block_size = 64
class SHA256(HashAlgorithm):
name = "sha256"
digest_size = 32
block_size = 64
class SHA384(HashAlgorithm):
name = "sha384"
digest_size = 48
block_size = 128
class SHA512(HashAlgorithm):
name = "sha512"
digest_size = 64
block_size = 128
class SHA3_224(HashAlgorithm): # noqa: N801
name = "sha3-224"
digest_size = 28
block_size = None
class SHA3_256(HashAlgorithm): # noqa: N801
name = "sha3-256"
digest_size = 32
block_size = None
class SHA3_384(HashAlgorithm): # noqa: N801
name = "sha3-384"
digest_size = 48
block_size = None
class SHA3_512(HashAlgorithm): # noqa: N801
name = "sha3-512"
digest_size = 64
block_size = None
class SHAKE128(HashAlgorithm, ExtendableOutputFunction):
name = "shake128"
block_size = None
def __init__(self, digest_size: int):
if not isinstance(digest_size, int):
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")
class SHAKE256(HashAlgorithm, ExtendableOutputFunction):
name = "shake256"
block_size = None
def __init__(self, digest_size: int):
if not isinstance(digest_size, int):
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")
class MD5(HashAlgorithm):
name = "md5"
digest_size = 16
block_size = 64
class BLAKE2b(HashAlgorithm):
name = "blake2b"
_max_digest_size = 64
_min_digest_size = 1
block_size = 128
def __init__(self, digest_size: int):
if digest_size != 64:
raise ValueError("Digest size must be 64")
self._digest_size = digest_size
digest_size = utils.read_only_property("_digest_size")
class BLAKE2s(HashAlgorithm):
name = "blake2s"
block_size = 64
_max_digest_size = 32
_min_digest_size = 1
def __init__(self, digest_size: int):
if digest_size != 32:
raise ValueError("Digest size must be 32")
self._digest_size = digest_size
digest_size = utils.read_only_property("_digest_size")