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#. Copyright (C) 2005-2010 Gregory P. Smith (greg@krypto.org)
# Licensed to PSF under a Contributor Agreement.
#
__doc__ = """hashlib module - A common interface to many hash functions.
new(name, data=b'', **kwargs) - returns a new hash object implementing the
given hash function; initializing the hash
using the given binary data.
Named constructor functions are also available, these are faster
than using new(name):
md5(), sha1(), sha224(), sha256(), sha384(), sha512(), blake2b(), blake2s(),
sha3_224, sha3_256, sha3_384, sha3_512, shake_128, and shake_256.
More algorithms may be available on your platform but the above are guaranteed
to exist. See the algorithms_guaranteed and algorithms_available attributes
to find out what algorithm names can be passed to new().
NOTE: If you want the adler32 or crc32 hash functions they are available in
the zlib module.
Choose your hash function wisely. Some have known collision weaknesses.
sha384 and sha512 will be slow on 32 bit platforms.
Hash objects have these methods:
- update(data): Update the hash object with the bytes in data. Repeated calls
are equivalent to a single call with the concatenation of all
the arguments.
- digest(): Return the digest of the bytes passed to the update() method
so far as a bytes object.
- hexdigest(): Like digest() except the digest is returned as a string
of double length, containing only hexadecimal digits.
- copy(): Return a copy (clone) of the hash object. This can be used to
efficiently compute the digests of datas that share a common
initial substring.
For example, to obtain the digest of the byte string 'Nobody inspects the
spammish repetition':
>>> import hashlib
>>> m = hashlib.md5()
>>> m.update(b"Nobody inspects")
>>> m.update(b" the spammish repetition")
>>> m.digest()
b'\\xbbd\\x9c\\x83\\xdd\\x1e\\xa5\\xc9\\xd9\\xde\\xc9\\xa1\\x8d\\xf0\\xff\\xe9'
More condensed:
>>> hashlib.sha224(b"Nobody inspects the spammish repetition").hexdigest()
'a4337bc45a8fc544c03f52dc550cd6e1e87021bc896588bd79e901e2'
"""
# This tuple and __get_builtin_constructor() must be modified if a new
# always available algorithm is added.
__always_supported = ('md5', 'sha1', 'sha224', 'sha256', 'sha384', 'sha512',
'blake2b', 'blake2s',
'sha3_224', 'sha3_256', 'sha3_384', 'sha3_512',
'shake_128', 'shake_256')
algorithms_guaranteed = set(__always_supported)
algorithms_available = set(__always_supported)
__all__ = __always_supported + ('new', 'algorithms_guaranteed',
'algorithms_available', 'pbkdf2_hmac')
try:
from _hashlib import get_fips_mode as _hashlib_get_fips_mode
except ImportError:
def _hashlib_get_fips_mode():
return 0
__builtin_constructor_cache = {}
def __get_builtin_constructor(name, *, _hashlib_get_fips_mode=_hashlib_get_fips_mode):
cache = __builtin_constructor_cache
constructor = cache.get(name)
if constructor is not None:
return constructor
try:
if not _hashlib_get_fips_mode():
if name in ('SHA1', 'sha1'):
import _sha1
cache['SHA1'] = cache['sha1'] = _sha1.sha1
elif name in ('MD5', 'md5'):
import _md5
cache['MD5'] = cache['md5'] = _md5.md5
elif name in ('SHA256', 'sha256', 'SHA224', 'sha224'):
import _sha256
cache['SHA224'] = cache['sha224'] = _sha256.sha224
cache['SHA256'] = cache['sha256'] = _sha256.sha256
elif name in ('SHA512', 'sha512', 'SHA384', 'sha384'):
import _sha512
cache['SHA384'] = cache['sha384'] = _sha512.sha384
cache['SHA512'] = cache['sha512'] = _sha512.sha512
if name in ('blake2b', 'blake2s'):
import _blake2
cache['blake2b'] = _blake2.blake2b
cache['blake2s'] = _blake2.blake2s
elif name in {'sha3_224', 'sha3_256', 'sha3_384', 'sha3_512',
'shake_128', 'shake_256'}:
import _sha3
cache['sha3_224'] = _sha3.sha3_224
cache['sha3_256'] = _sha3.sha3_256
cache['sha3_384'] = _sha3.sha3_384
cache['sha3_512'] = _sha3.sha3_512
cache['shake_128'] = _sha3.shake_128
cache['shake_256'] = _sha3.shake_256
except ImportError:
pass # no extension module, this hash is unsupported.
constructor = cache.get(name)
if constructor is not None:
return constructor
raise ValueError('unsupported hash type ' + name)
def __get_openssl_constructor(name):
if name in {
'blake2b', 'blake2s', 'shake_256', 'shake_128',
'sha3_224', 'sha3_256', 'sha3_384', 'sha3_512',
}:
# Prefer our blake2 implementation.
return __get_builtin_constructor(name)
try:
f = getattr(_hashlib, 'openssl_' + name)
# Allow the C module to raise ValueError. The function will be
# defined but the hash not actually available thanks to OpenSSL.
if not _hashlib.get_fips_mode():
# N.B. In "FIPS mode", there is no fallback.
# If this test fails, we want to export the broken hash
# constructor anyway.
f()
# Use the C function directly (very fast)
return f
except (AttributeError, ValueError):
return __get_builtin_constructor(name)
if not _hashlib_get_fips_mode():
def __py_new(name, data=b'', **kwargs):
"""new(name, data=b'', **kwargs) - Return a new hashing object using the
named algorithm; optionally initialized with data (which must be
a bytes-like object).
"""
return __get_builtin_constructor(name)(data, **kwargs)
def __hash_new(name, data=b'', **kwargs):
"""new(name, data=b'') - Return a new hashing object using the named algorithm;
optionally initialized with data (which must be a bytes-like object).
"""
if _hashlib.get_fips_mode():
# Use OpenSSL names for Python built-in hashes
orig_name = name
name = {
'sha3_224': "sha3-224",
'sha3_256': "sha3-256",
'sha3_384': "sha3-384",
'sha3_512': "sha3-512",
'shake_128': "shake128",
'shake_256': "shake256",
}.get(name, name)
else:
if name in {'blake2b', 'blake2s'}:
# Prefer our blake2 implementation.
# OpenSSL 1.1.0 comes with a limited implementation of blake2b/s.
# It does neither support keyed blake2 nor advanced features like
# salt, personal, tree hashing or SSE.
return __get_builtin_constructor(name)(data, **kwargs)
try:
usedforsecurity = kwargs.pop('usedforsecurity', True)
retval = _hashlib.new(
name, data, usedforsecurity=usedforsecurity)
if _hashlib.get_fips_mode() and name != orig_name:
retval._set_name(orig_name)
return retval
except ValueError:
# If the _hashlib module (OpenSSL) doesn't support the named
# hash, try using our builtin implementations.
# This allows for SHA224/256 and SHA384/512 support even though
# the OpenSSL library prior to 0.9.8 doesn't provide them.
if _hashlib.get_fips_mode():
raise
return __get_builtin_constructor(name)(data, **kwargs)
try:
import _hashlib
new = __hash_new
__get_hash = __get_openssl_constructor
algorithms_available = algorithms_available.union(
_hashlib.openssl_md_meth_names)
except ImportError:
new = __py_new
__get_hash = __get_builtin_constructor
# OpenSSL's PKCS5_PBKDF2_HMAC requires OpenSSL 1.0+ with HMAC and SHA
from _hashlib import pbkdf2_hmac
try:
# OpenSSL's scrypt requires OpenSSL 1.1+
from _hashlib import scrypt
except ImportError:
pass
for __func_name in __always_supported:
# try them all, some may not work due to the OpenSSL
# version not supporting that algorithm.
try:
globals()[__func_name] = __get_hash(__func_name)
except ValueError:
if not _hashlib_get_fips_mode():
import logging
logging.exception('code for hash %s was not found.', __func_name)
# Cleanup locals()
del __always_supported, __func_name, __get_hash
del __hash_new, __get_openssl_constructor
if not _hashlib.get_fips_mode():
del __py_new
del _hashlib_get_fips_mode