1 #. Copyright (C) 2005-2010 Gregory P. Smith (greg (at] krypto.org) 2 # Licensed to PSF under a Contributor Agreement. 3 # 4 5 __doc__ = """hashlib module - A common interface to many hash functions. 6 7 new(name, data=b'', **kwargs) - returns a new hash object implementing the 8 given hash function; initializing the hash 9 using the given binary data. 10 11 Named constructor functions are also available, these are faster 12 than using new(name): 13 14 md5(), sha1(), sha224(), sha256(), sha384(), sha512(), blake2b(), blake2s(), 15 sha3_224, sha3_256, sha3_384, sha3_512, shake_128, and shake_256. 16 17 More algorithms may be available on your platform but the above are guaranteed 18 to exist. See the algorithms_guaranteed and algorithms_available attributes 19 to find out what algorithm names can be passed to new(). 20 21 NOTE: If you want the adler32 or crc32 hash functions they are available in 22 the zlib module. 23 24 Choose your hash function wisely. Some have known collision weaknesses. 25 sha384 and sha512 will be slow on 32 bit platforms. 26 27 Hash objects have these methods: 28 - update(data): Update the hash object with the bytes in data. Repeated calls 29 are equivalent to a single call with the concatenation of all 30 the arguments. 31 - digest(): Return the digest of the bytes passed to the update() method 32 so far as a bytes object. 33 - hexdigest(): Like digest() except the digest is returned as a string 34 of double length, containing only hexadecimal digits. 35 - copy(): Return a copy (clone) of the hash object. This can be used to 36 efficiently compute the digests of datas that share a common 37 initial substring. 38 39 For example, to obtain the digest of the byte string 'Nobody inspects the 40 spammish repetition': 41 42 >>> import hashlib 43 >>> m = hashlib.md5() 44 >>> m.update(b"Nobody inspects") 45 >>> m.update(b" the spammish repetition") 46 >>> m.digest() 47 b'\\xbbd\\x9c\\x83\\xdd\\x1e\\xa5\\xc9\\xd9\\xde\\xc9\\xa1\\x8d\\xf0\\xff\\xe9' 48 49 More condensed: 50 51 >>> hashlib.sha224(b"Nobody inspects the spammish repetition").hexdigest() 52 'a4337bc45a8fc544c03f52dc550cd6e1e87021bc896588bd79e901e2' 53 54 """ 55 56 # This tuple and __get_builtin_constructor() must be modified if a new 57 # always available algorithm is added. 58 __always_supported = ('md5', 'sha1', 'sha224', 'sha256', 'sha384', 'sha512', 59 'blake2b', 'blake2s', 60 'sha3_224', 'sha3_256', 'sha3_384', 'sha3_512', 61 'shake_128', 'shake_256') 62 63 64 algorithms_guaranteed = set(__always_supported) 65 algorithms_available = set(__always_supported) 66 67 __all__ = __always_supported + ('new', 'algorithms_guaranteed', 68 'algorithms_available', 'pbkdf2_hmac') 69 70 71 __builtin_constructor_cache = {} 72 73 def __get_builtin_constructor(name): 74 cache = __builtin_constructor_cache 75 constructor = cache.get(name) 76 if constructor is not None: 77 return constructor 78 try: 79 if name in ('SHA1', 'sha1'): 80 import _sha1 81 cache['SHA1'] = cache['sha1'] = _sha1.sha1 82 elif name in ('MD5', 'md5'): 83 import _md5 84 cache['MD5'] = cache['md5'] = _md5.md5 85 elif name in ('SHA256', 'sha256', 'SHA224', 'sha224'): 86 import _sha256 87 cache['SHA224'] = cache['sha224'] = _sha256.sha224 88 cache['SHA256'] = cache['sha256'] = _sha256.sha256 89 elif name in ('SHA512', 'sha512', 'SHA384', 'sha384'): 90 import _sha512 91 cache['SHA384'] = cache['sha384'] = _sha512.sha384 92 cache['SHA512'] = cache['sha512'] = _sha512.sha512 93 elif name in ('blake2b', 'blake2s'): 94 import _blake2 95 cache['blake2b'] = _blake2.blake2b 96 cache['blake2s'] = _blake2.blake2s 97 elif name in {'sha3_224', 'sha3_256', 'sha3_384', 'sha3_512', 98 'shake_128', 'shake_256'}: 99 import _sha3 100 cache['sha3_224'] = _sha3.sha3_224 101 cache['sha3_256'] = _sha3.sha3_256 102 cache['sha3_384'] = _sha3.sha3_384 103 cache['sha3_512'] = _sha3.sha3_512 104 cache['shake_128'] = _sha3.shake_128 105 cache['shake_256'] = _sha3.shake_256 106 except ImportError: 107 pass # no extension module, this hash is unsupported. 108 109 constructor = cache.get(name) 110 if constructor is not None: 111 return constructor 112 113 raise ValueError('unsupported hash type ' + name) 114 115 116 def __get_openssl_constructor(name): 117 if name in {'blake2b', 'blake2s'}: 118 # Prefer our blake2 implementation. 119 return __get_builtin_constructor(name) 120 try: 121 f = getattr(_hashlib, 'openssl_' + name) 122 # Allow the C module to raise ValueError. The function will be 123 # defined but the hash not actually available thanks to OpenSSL. 124 f() 125 # Use the C function directly (very fast) 126 return f 127 except (AttributeError, ValueError): 128 return __get_builtin_constructor(name) 129 130 131 def __py_new(name, data=b'', **kwargs): 132 """new(name, data=b'', **kwargs) - Return a new hashing object using the 133 named algorithm; optionally initialized with data (which must be 134 a bytes-like object). 135 """ 136 return __get_builtin_constructor(name)(data, **kwargs) 137 138 139 def __hash_new(name, data=b'', **kwargs): 140 """new(name, data=b'') - Return a new hashing object using the named algorithm; 141 optionally initialized with data (which must be a bytes-like object). 142 """ 143 if name in {'blake2b', 'blake2s'}: 144 # Prefer our blake2 implementation. 145 # OpenSSL 1.1.0 comes with a limited implementation of blake2b/s. 146 # It does neither support keyed blake2 nor advanced features like 147 # salt, personal, tree hashing or SSE. 148 return __get_builtin_constructor(name)(data, **kwargs) 149 try: 150 return _hashlib.new(name, data) 151 except ValueError: 152 # If the _hashlib module (OpenSSL) doesn't support the named 153 # hash, try using our builtin implementations. 154 # This allows for SHA224/256 and SHA384/512 support even though 155 # the OpenSSL library prior to 0.9.8 doesn't provide them. 156 return __get_builtin_constructor(name)(data) 157 158 159 try: 160 import _hashlib 161 new = __hash_new 162 __get_hash = __get_openssl_constructor 163 algorithms_available = algorithms_available.union( 164 _hashlib.openssl_md_meth_names) 165 except ImportError: 166 new = __py_new 167 __get_hash = __get_builtin_constructor 168 169 try: 170 # OpenSSL's PKCS5_PBKDF2_HMAC requires OpenSSL 1.0+ with HMAC and SHA 171 from _hashlib import pbkdf2_hmac 172 except ImportError: 173 _trans_5C = bytes((x ^ 0x5C) for x in range(256)) 174 _trans_36 = bytes((x ^ 0x36) for x in range(256)) 175 176 def pbkdf2_hmac(hash_name, password, salt, iterations, dklen=None): 177 """Password based key derivation function 2 (PKCS #5 v2.0) 178 179 This Python implementations based on the hmac module about as fast 180 as OpenSSL's PKCS5_PBKDF2_HMAC for short passwords and much faster 181 for long passwords. 182 """ 183 if not isinstance(hash_name, str): 184 raise TypeError(hash_name) 185 186 if not isinstance(password, (bytes, bytearray)): 187 password = bytes(memoryview(password)) 188 if not isinstance(salt, (bytes, bytearray)): 189 salt = bytes(memoryview(salt)) 190 191 # Fast inline HMAC implementation 192 inner = new(hash_name) 193 outer = new(hash_name) 194 blocksize = getattr(inner, 'block_size', 64) 195 if len(password) > blocksize: 196 password = new(hash_name, password).digest() 197 password = password + b'\x00' * (blocksize - len(password)) 198 inner.update(password.translate(_trans_36)) 199 outer.update(password.translate(_trans_5C)) 200 201 def prf(msg, inner=inner, outer=outer): 202 # PBKDF2_HMAC uses the password as key. We can re-use the same 203 # digest objects and just update copies to skip initialization. 204 icpy = inner.copy() 205 ocpy = outer.copy() 206 icpy.update(msg) 207 ocpy.update(icpy.digest()) 208 return ocpy.digest() 209 210 if iterations < 1: 211 raise ValueError(iterations) 212 if dklen is None: 213 dklen = outer.digest_size 214 if dklen < 1: 215 raise ValueError(dklen) 216 217 dkey = b'' 218 loop = 1 219 from_bytes = int.from_bytes 220 while len(dkey) < dklen: 221 prev = prf(salt + loop.to_bytes(4, 'big')) 222 # endianness doesn't matter here as long to / from use the same 223 rkey = int.from_bytes(prev, 'big') 224 for i in range(iterations - 1): 225 prev = prf(prev) 226 # rkey = rkey ^ prev 227 rkey ^= from_bytes(prev, 'big') 228 loop += 1 229 dkey += rkey.to_bytes(inner.digest_size, 'big') 230 231 return dkey[:dklen] 232 233 try: 234 # OpenSSL's scrypt requires OpenSSL 1.1+ 235 from _hashlib import scrypt 236 except ImportError: 237 pass 238 239 240 for __func_name in __always_supported: 241 # try them all, some may not work due to the OpenSSL 242 # version not supporting that algorithm. 243 try: 244 globals()[__func_name] = __get_hash(__func_name) 245 except ValueError: 246 import logging 247 logging.exception('code for hash %s was not found.', __func_name) 248 249 250 # Cleanup locals() 251 del __always_supported, __func_name, __get_hash 252 del __py_new, __hash_new, __get_openssl_constructor 253
