217 lines
7.8 KiB
Python
217 lines
7.8 KiB
Python
#. Copyright (C) 2005-2010 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, data=b'') - returns a new hash object implementing the
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given hash function; initializing the hash
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using the given binary data.
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Named constructor functions are also available, these are faster
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than using new(name):
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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 guaranteed
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to exist. See the algorithms_guaranteed and algorithms_available attributes
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to find out what algorithm names can be passed to new().
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NOTE: If you want the adler32 or crc32 hash functions they are available in
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the zlib module.
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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 bytes in 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 bytes passed to the update() method
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so far.
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- hexdigest(): Like digest() except the digest is returned as a unicode
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object of 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(b"Nobody inspects")
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>>> m.update(b" the spammish repetition")
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>>> m.digest()
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b'\\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(b"Nobody inspects the spammish repetition").hexdigest()
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'a4337bc45a8fc544c03f52dc550cd6e1e87021bc896588bd79e901e2'
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"""
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# This tuple and __get_builtin_constructor() must be modified if a new
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# always available algorithm is added.
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__always_supported = ('md5', 'sha1', 'sha224', 'sha256', 'sha384', 'sha512')
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algorithms_guaranteed = set(__always_supported)
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algorithms_available = set(__always_supported)
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__all__ = __always_supported + ('new', 'algorithms_guaranteed',
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'algorithms_available', 'pbkdf2_hmac')
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__builtin_constructor_cache = {}
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def __get_builtin_constructor(name):
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cache = __builtin_constructor_cache
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constructor = cache.get(name)
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if constructor is not None:
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return constructor
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try:
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if name in ('SHA1', 'sha1'):
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import _sha1
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cache['SHA1'] = cache['sha1'] = _sha1.sha1
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elif name in ('MD5', 'md5'):
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import _md5
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cache['MD5'] = cache['md5'] = _md5.md5
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elif name in ('SHA256', 'sha256', 'SHA224', 'sha224'):
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import _sha256
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cache['SHA224'] = cache['sha224'] = _sha256.sha224
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cache['SHA256'] = cache['sha256'] = _sha256.sha256
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elif name in ('SHA512', 'sha512', 'SHA384', 'sha384'):
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import _sha512
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cache['SHA384'] = cache['sha384'] = _sha512.sha384
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cache['SHA512'] = cache['sha512'] = _sha512.sha512
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except ImportError:
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pass # no extension module, this hash is unsupported.
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constructor = cache.get(name)
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if constructor is not None:
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return constructor
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raise ValueError('unsupported hash type ' + name)
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def __get_openssl_constructor(name):
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try:
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f = getattr(_hashlib, 'openssl_' + name)
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# Allow the C module to raise ValueError. The function will be
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# defined but the hash not actually available thanks to OpenSSL.
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f()
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# Use the C function directly (very fast)
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return f
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except (AttributeError, ValueError):
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return __get_builtin_constructor(name)
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def __py_new(name, data=b''):
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"""new(name, data=b'') - Return a new hashing object using the named algorithm;
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optionally initialized with data (which must be bytes).
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"""
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return __get_builtin_constructor(name)(data)
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def __hash_new(name, data=b''):
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"""new(name, data=b'') - Return a new hashing object using the named algorithm;
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optionally initialized with data (which must be bytes).
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"""
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try:
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return _hashlib.new(name, data)
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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)(data)
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try:
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import _hashlib
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new = __hash_new
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__get_hash = __get_openssl_constructor
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algorithms_available = algorithms_available.union(
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_hashlib.openssl_md_meth_names)
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except ImportError:
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new = __py_new
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__get_hash = __get_builtin_constructor
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try:
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# OpenSSL's PKCS5_PBKDF2_HMAC requires OpenSSL 1.0+ with HMAC and SHA
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from _hashlib import pbkdf2_hmac
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except ImportError:
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_trans_5C = bytes((x ^ 0x5C) for x in range(256))
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_trans_36 = bytes((x ^ 0x36) for x in range(256))
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def pbkdf2_hmac(hash_name, password, salt, iterations, dklen=None):
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"""Password based key derivation function 2 (PKCS #5 v2.0)
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This Python implementations based on the hmac module about as fast
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as OpenSSL's PKCS5_PBKDF2_HMAC for short passwords and much faster
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for long passwords.
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"""
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if not isinstance(hash_name, str):
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raise TypeError(hash_name)
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if not isinstance(password, (bytes, bytearray)):
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password = bytes(memoryview(password))
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if not isinstance(salt, (bytes, bytearray)):
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salt = bytes(memoryview(salt))
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# Fast inline HMAC implementation
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inner = new(hash_name)
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outer = new(hash_name)
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blocksize = getattr(inner, 'block_size', 64)
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if len(password) > blocksize:
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password = new(hash_name, password).digest()
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password = password + b'\x00' * (blocksize - len(password))
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inner.update(password.translate(_trans_36))
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outer.update(password.translate(_trans_5C))
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def prf(msg, inner=inner, outer=outer):
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# PBKDF2_HMAC uses the password as key. We can re-use the same
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# digest objects and just update copies to skip initialization.
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icpy = inner.copy()
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ocpy = outer.copy()
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icpy.update(msg)
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ocpy.update(icpy.digest())
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return ocpy.digest()
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if iterations < 1:
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raise ValueError(iterations)
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if dklen is None:
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dklen = outer.digest_size
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if dklen < 1:
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raise ValueError(dklen)
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dkey = b''
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loop = 1
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from_bytes = int.from_bytes
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while len(dkey) < dklen:
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prev = prf(salt + loop.to_bytes(4, 'big'))
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# endianess doesn't matter here as long to / from use the same
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rkey = int.from_bytes(prev, 'big')
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for i in range(iterations - 1):
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prev = prf(prev)
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# rkey = rkey ^ prev
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rkey ^= from_bytes(prev, 'big')
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loop += 1
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dkey += rkey.to_bytes(inner.digest_size, 'big')
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return dkey[:dklen]
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for __func_name in __always_supported:
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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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try:
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globals()[__func_name] = __get_hash(__func_name)
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except ValueError:
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import logging
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logging.exception('code for hash %s was not found.', __func_name)
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# Cleanup locals()
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del __always_supported, __func_name, __get_hash
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del __py_new, __hash_new, __get_openssl_constructor
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