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138 lines
4.7 KiB
Python
138 lines
4.7 KiB
Python
# $Id$
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#
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# Copyright (C) 2005-2007 Gregory P. Smith (greg@krypto.org)
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# Licensed to PSF under a Contributor Agreement.
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#
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__doc__ = """hashlib module - A common interface to many hash functions.
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new(name, string='') - returns a new hash object implementing the
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given hash function; initializing the hash
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using the given string data.
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Named constructor functions are also available, these are much faster
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than using new():
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md5(), sha1(), sha224(), sha256(), sha384(), and sha512()
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More algorithms may be available on your platform but the above are
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guaranteed to exist.
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Choose your hash function wisely. Some have known collision weaknesses.
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sha384 and sha512 will be slow on 32 bit platforms.
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Hash objects have these methods:
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- update(arg): Update the hash object with the string arg. Repeated calls
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are equivalent to a single call with the concatenation of all
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the arguments.
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- digest(): Return the digest of the strings passed to the update() method
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so far. This may contain non-ASCII characters, including
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NUL bytes.
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- hexdigest(): Like digest() except the digest is returned as a string of
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double length, containing only hexadecimal digits.
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- copy(): Return a copy (clone) of the hash object. This can be used to
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efficiently compute the digests of strings that share a common
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initial substring.
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For example, to obtain the digest of the string 'Nobody inspects the
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spammish repetition':
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>>> import hashlib
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>>> m = hashlib.md5()
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>>> m.update("Nobody inspects")
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>>> m.update(" the spammish repetition")
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>>> m.digest()
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'\xbbd\x9c\x83\xdd\x1e\xa5\xc9\xd9\xde\xc9\xa1\x8d\xf0\xff\xe9'
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More condensed:
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>>> hashlib.sha224("Nobody inspects the spammish repetition").hexdigest()
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'a4337bc45a8fc544c03f52dc550cd6e1e87021bc896588bd79e901e2'
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"""
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def __get_builtin_constructor(name):
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if name in ('SHA1', 'sha1'):
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import _sha
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return _sha.new
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elif name in ('MD5', 'md5'):
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import _md5
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return _md5.new
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elif name in ('SHA256', 'sha256', 'SHA224', 'sha224'):
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import _sha256
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bs = name[3:]
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if bs == '256':
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return _sha256.sha256
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elif bs == '224':
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return _sha256.sha224
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elif name in ('SHA512', 'sha512', 'SHA384', 'sha384'):
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import _sha512
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bs = name[3:]
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if bs == '512':
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return _sha512.sha512
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elif bs == '384':
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return _sha512.sha384
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raise ValueError, "unsupported hash type"
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def __py_new(name, string=''):
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"""new(name, string='') - Return a new hashing object using the named algorithm;
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optionally initialized with a string.
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"""
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return __get_builtin_constructor(name)(string)
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def __hash_new(name, string=''):
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"""new(name, string='') - Return a new hashing object using the named algorithm;
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optionally initialized with a string.
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"""
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try:
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return _hashlib.new(name, string)
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except ValueError:
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# If the _hashlib module (OpenSSL) doesn't support the named
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# hash, try using our builtin implementations.
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# This allows for SHA224/256 and SHA384/512 support even though
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# the OpenSSL library prior to 0.9.8 doesn't provide them.
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return __get_builtin_constructor(name)(string)
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try:
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import _hashlib
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# use the wrapper of the C implementation
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new = __hash_new
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for opensslFuncName in filter(lambda n: n.startswith('openssl_'), dir(_hashlib)):
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funcName = opensslFuncName[len('openssl_'):]
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try:
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# try them all, some may not work due to the OpenSSL
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# version not supporting that algorithm.
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f = getattr(_hashlib, opensslFuncName)
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f()
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# Use the C function directly (very fast)
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exec(funcName + ' = f')
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except ValueError:
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try:
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# Use the builtin implementation directly (fast)
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exec(funcName + ' = __get_builtin_constructor(funcName)')
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except ValueError:
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# this one has no builtin implementation, don't define it
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pass
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# clean up our locals
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del f
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del opensslFuncName
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del funcName
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except ImportError:
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# We don't have the _hashlib OpenSSL module?
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# use the built in legacy interfaces via a wrapper function
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new = __py_new
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# lookup the C function to use directly for the named constructors
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md5 = __get_builtin_constructor('md5')
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sha1 = __get_builtin_constructor('sha1')
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sha224 = __get_builtin_constructor('sha224')
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sha256 = __get_builtin_constructor('sha256')
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sha384 = __get_builtin_constructor('sha384')
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sha512 = __get_builtin_constructor('sha512')
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