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+# $Id$
+#
+# Copyright (C) 2005 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, 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.
+
+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(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'
+
+"""
+
+# 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')
+
+algorithms = __always_supported
+
+__all__ = __always_supported + ('new', 'algorithms')
+
+
+def __get_builtin_constructor(name):
+ try:
+ 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
+ except ImportError:
+ pass # no extension module, this hash is unsupported.
+
+ raise ValueError('unsupported hash type ' + name)
+
+
+def __get_openssl_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.
+ f()
+ # Use the C function directly (very fast)
+ return f
+ except (AttributeError, ValueError):
+ return __get_builtin_constructor(name)
+
+
+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
+ new = __hash_new
+ __get_hash = __get_openssl_constructor
+except ImportError:
+ new = __py_new
+ __get_hash = __get_builtin_constructor
+
+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:
+ import logging
+ logging.exception('code for hash %s was not found.', __func_name)
+
+# Cleanup locals()
+del __always_supported, __func_name, __get_hash
+del __py_new, __hash_new, __get_openssl_constructor