#. Copyright (C) 2005-2010 Gregory P. Smith ([email protected])

# 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.

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',

'sha3_224', 'sha3_256', 'sha3_384', 'sha3_512')

algorithms_guaranteed = set(__always_supported)

algorithms_available = set(__always_supported)

__all__ = __always_supported + ('new', 'algorithms_guaranteed',

'algorithms_available', 'pbkdf2_hmac')

__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

elif name in {'sha3_224', 'sha3_256', 'sha3_384', 'sha3_512',

'SHA3_224', 'SHA3_256', 'SHA3_384', 'SHA3_512'}:

import _sha3

cache['SHA3_224'] = cache['sha3_224'] = _sha3.sha3_224

cache['SHA3_256'] = cache['sha3_256'] = _sha3.sha3_256

cache['SHA3_384'] = cache['sha3_384'] = _sha3.sha3_384

cache['SHA3_512'] = cache['sha3_512'] = _sha3.sha3_512

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.

f()

# Use the C function directly (very fast)

return f

except (AttributeError, ValueError):

return __get_builtin_constructor(name)

def __py_new(name, data=b''):

"""new(name, data=b'') - Return a new hashing object using the named algorithm;

optionally initialized with data (which must be bytes).

"""

return __get_builtin_constructor(name)(data)

def __hash_new(name, data=b''):

"""new(name, data=b'') - Return a new hashing object using the named algorithm;

optionally initialized with data (which must be bytes).

"""

try:

return _hashlib.new(name, data)

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)(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 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:

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