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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'') - 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(), and sha512() 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. If the underlying implementation supports "FIPS mode", and this is enabled, it may restrict the available hashes to only those that are compliant with FIPS regulations. For example, it may deny the use of MD5, on the grounds that this is not secure for uses such as authentication, system integrity checking, or digital signatures. If you need to use such a hash for non-security purposes (such as indexing into a data structure for speed), you can override the keyword argument "usedforsecurity" from True to False to signify that your code is not relying on the hash for security purposes, and this will allow the hash to be usable even in FIPS mode. Hash objects have these methods: - update(arg): Update the hash object with the bytes in arg. 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. - hexdigest(): Like digest() except the digest is returned as a unicode object 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(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') algorithms_guaranteed = set(__always_supported) algorithms_available = set(__always_supported) __all__ = __always_supported + ('new', 'algorithms_guaranteed', 'algorithms_available', 'pbkdf2_hmac') import functools def __ignore_usedforsecurity(func): """Used for sha3_* functions. Until OpenSSL implements them, we want to use them from Python _sha3 module, but we want them to accept usedforsecurity argument too.""" # TODO: remove this function when OpenSSL implements sha3 @functools.wraps(func) def inner(*args, **kwargs): if 'usedforsecurity' in kwargs: kwargs.pop('usedforsecurity') return func(*args, **kwargs) return inner __builtin_constructor_cache = {} def __get_builtin_constructor(name): cache = __builtin_constructor_cache constructor = cache.get(name) if constructor is not None: return constructor try: 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 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): 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. # We pass "usedforsecurity=False" to disable FIPS-based restrictions: # at this stage we're merely seeing if the function is callable, # rather than using it for actual work. f(usedforsecurity=False) # Use the C function directly (very fast) return f except (AttributeError, ValueError): # TODO: We want to just raise here when OpenSSL implements sha3 # because we want to make sure that Fedora uses everything from OpenSSL return __get_builtin_constructor(name) def __py_new(name, data=b'', usedforsecurity=True): """new(name, data=b'', usedforsecurity=True) - Return a new hashing object using the named algorithm; optionally initialized with data (which must be bytes). The 'usedforsecurity' keyword argument does nothing, and is for compatibilty with the OpenSSL implementation """ return __get_builtin_constructor(name)(data) def __hash_new(name, data=b'', usedforsecurity=True): """new(name, data=b'', usedforsecurity=True) - Return a new hashing object using the named algorithm; optionally initialized with data (which must be bytes). Override 'usedforsecurity' to False when using for non-security purposes in a FIPS environment """ try: return _hashlib.new(name, data, usedforsecurity) except ValueError: # TODO: We want to just raise here when OpenSSL implements sha3 # because we want to make sure that Fedora uses everything from OpenSSL return __get_builtin_constructor(name)(data) 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 try: # OpenSSL's PKCS5_PBKDF2_HMAC requires OpenSSL 1.0+ with HMAC and SHA from _hashlib import pbkdf2_hmac except ImportError: _trans_5C = bytes((x ^ 0x5C) for x in range(256)) _trans_36 = bytes((x ^ 0x36) for x in range(256)) def pbkdf2_hmac(hash_name, password, salt, iterations, dklen=None): """Password based key derivation function 2 (PKCS #5 v2.0) This Python implementations based on the hmac module about as fast as OpenSSL's PKCS5_PBKDF2_HMAC for short passwords and much faster for long passwords. """ if not isinstance(hash_name, str): raise TypeError(hash_name) if not isinstance(password, (bytes, bytearray)): password = bytes(memoryview(password)) if not isinstance(salt, (bytes, bytearray)): salt = bytes(memoryview(salt)) # Fast inline HMAC implementation inner = new(hash_name) outer = new(hash_name) blocksize = getattr(inner, 'block_size', 64) if len(password) > blocksize: password = new(hash_name, password).digest() password = password + b'\x00' * (blocksize - len(password)) inner.update(password.translate(_trans_36)) outer.update(password.translate(_trans_5C)) def prf(msg, inner=inner, outer=outer): # PBKDF2_HMAC uses the password as key. We can re-use the same # digest objects and just update copies to skip initialization. icpy = inner.copy() ocpy = outer.copy() icpy.update(msg) ocpy.update(icpy.digest()) return ocpy.digest() if iterations < 1: raise ValueError(iterations) if dklen is None: dklen = outer.digest_size if dklen < 1: raise ValueError(dklen) dkey = b'' loop = 1 from_bytes = int.from_bytes while len(dkey) < dklen: prev = prf(salt + loop.to_bytes(4, 'big')) # endianess doesn't matter here as long to / from use the same rkey = int.from_bytes(prev, 'big') for i in range(iterations - 1): prev = prf(prev) # rkey = rkey ^ prev rkey ^= from_bytes(prev, 'big') loop += 1 dkey += rkey.to_bytes(inner.digest_size, 'big') return dkey[:dklen] for __func_name in __always_supported: # try them all, some may not work due to the OpenSSL # version not supporting that algorithm. try: func = __get_hash(__func_name) if 'sha3_' in __func_name: func = __ignore_usedforsecurity(func) globals()[__func_name] = func 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 del __ignore_usedforsecurity