ref: 2ca8e31066e7d67977aacae0980ffa27deaa6f18
dir: /sys/lib/python/hashlib.py/
# $Id: hashlib.py 52533 2006-10-29 18:01:12Z georg.brandl $
#
# Copyright (C) 2005 Gregory P. Smith ([email protected])
# Licensed to PSF under a Contributor Agreement.
#
__doc__ = """hashlib module - A common interface to many hash functions.
new(name, string='') - returns a new hash object implementing the
given hash function; initializing the hash
using the given string data.
Named constructor functions are also available, these are much faster
than using new():
md5(), sha1(), sha224(), sha256(), sha384(), and sha512()
More algorithms may be available on your platform but the above are
guaranteed to exist.
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(arg): Update the hash object with the string arg. Repeated calls
are equivalent to a single call with the concatenation of all
the arguments.
- digest(): Return the digest of the strings passed to the update() method
so far. This may contain non-ASCII characters, including
NUL bytes.
- 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 strings that share a common
initial substring.
For example, to obtain the digest of the string 'Nobody inspects the
spammish repetition':
>>> import hashlib
>>> m = hashlib.md5()
>>> m.update("Nobody inspects")
>>> m.update(" the spammish repetition")
>>> m.digest()
'\xbbd\x9c\x83\xdd\x1e\xa5\xc9\xd9\xde\xc9\xa1\x8d\xf0\xff\xe9'
More condensed:
>>> hashlib.sha224("Nobody inspects the spammish repetition").hexdigest()
'a4337bc45a8fc544c03f52dc550cd6e1e87021bc896588bd79e901e2'
"""
def __get_builtin_constructor(name):
if name in ('SHA1', 'sha1'):
import _sha
return _sha.new
elif name in ('MD5', 'md5'):
import _md5
return _md5.new
elif name in ('SHA256', 'sha256', 'SHA224', 'sha224'):
import _sha256
bs = name[3:]
if bs == '256':
return _sha256.sha256
elif bs == '224':
return _sha256.sha224
# elif name in ('SHA512', 'sha512', 'SHA384', 'sha384'):
# import _sha512
# bs = name[3:]
# if bs == '512':
# return _sha512.sha512
# elif bs == '384':
# return _sha512.sha384
raise ValueError, "unsupported hash type"
def __py_new(name, string=''):
"""new(name, string='') - Return a new hashing object using the named algorithm;
optionally initialized with a string.
"""
return __get_builtin_constructor(name)(string)
def __hash_new(name, string=''):
"""new(name, string='') - Return a new hashing object using the named algorithm;
optionally initialized with a string.
"""
try:
return _hashlib.new(name, string)
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.
return __get_builtin_constructor(name)(string)
try:
import _hashlib
# use the wrapper of the C implementation
new = __hash_new
for opensslFuncName in filter(lambda n: n.startswith('openssl_'), dir(_hashlib)):
funcName = opensslFuncName[len('openssl_'):]
try:
# try them all, some may not work due to the OpenSSL
# version not supporting that algorithm.
f = getattr(_hashlib, opensslFuncName)
f()
# Use the C function directly (very fast)
exec funcName + ' = f'
except ValueError:
try:
# Use the builtin implementation directly (fast)
exec funcName + ' = __get_builtin_constructor(funcName)'
except ValueError:
# this one has no builtin implementation, don't define it
pass
# clean up our locals
del f
del opensslFuncName
del funcName
except ImportError:
# We don't have the _hashlib OpenSSL module?
# use the built in legacy interfaces via a wrapper function
new = __py_new
# lookup the C function to use directly for the named constructors
md5 = __get_builtin_constructor('md5')
sha1 = __get_builtin_constructor('sha1')
sha224 = __get_builtin_constructor('sha224')
sha256 = __get_builtin_constructor('sha256')
sha384 = __get_builtin_constructor('sha384')
sha512 = __get_builtin_constructor('sha512')