def safe_str_cmp(a, b):
"""This function compares strings in somewhat constant time. This
requires that the length of at least one string is known in advance.
Returns `True` if the two strings are equal, or `False` if they are not.
.. versionadded:: 0.7
"""
if isinstance(a, text_type):
a = a.encode('utf-8')
if isinstance(b, text_type):
b = b.encode('utf-8')
if _builtin_safe_str_cmp is not None:
return _builtin_safe_str_cmp(a, b)
if len(a) != len(b):
return False
rv = 0
if PY2:
for x, y in izip(a, b):
rv |= ord(x) ^ ord(y)
else:
for x, y in izip(a, b):
rv |= x ^ y
return rv == 0
def safe_str_cmp(a, b):
"""This function compares strings in somewhat constant time. This
requires that the length of at least one string is known in advance.
Returns `True` if the two strings are equal, or `False` if they are not.
.. versionadded:: 0.7
"""
if isinstance(a, text_type):
a = a.encode('utf-8')
if isinstance(b, text_type):
b = b.encode('utf-8')
if _builtin_safe_str_cmp is not None:
return _builtin_safe_str_cmp(a, b)
if len(a) != len(b):
return False
rv = 0
if PY2:
for x, y in izip(a, b):
rv |= ord(x) ^ ord(y)
else:
for x, y in izip(a, b):
rv |= x ^ y
return rv == 0
def pbkdf2_bin(data,
salt,
iterations=DEFAULT_PBKDF2_ITERATIONS,
keylen=None,
hashfunc=None):
"""Returns a binary digest for the PBKDF2 hash algorithm of `data`
with the given `salt`. It iterates `iterations` times and produces a
key of `keylen` bytes. By default, SHA-1 is used as hash function;
a different hashlib `hashfunc` can be provided.
.. versionadded:: 0.9
:param data: the data to derive.
:param salt: the salt for the derivation.
:param iterations: the number of iterations.
:param keylen: the length of the resulting key. If not provided
the digest size will be used.
:param hashfunc: the hash function to use. This can either be the
string name of a known hash function or a function
from the hashlib module. Defaults to sha1.
"""
if isinstance(hashfunc, string_types):
hashfunc = _hash_funcs[hashfunc]
elif not hashfunc:
hashfunc = hashlib.sha1
data = to_bytes(data)
salt = to_bytes(salt)
# If we're on Python with pbkdf2_hmac we can try to use it for
# compatible digests.
if _has_native_pbdkf2:
_test_hash = hashfunc()
if hasattr(_test_hash, 'name') and \
_test_hash.name in hashlib.algorithms_available:
return hashlib.pbkdf2_hmac(_test_hash.name, data, salt, iterations,
keylen)
mac = hmac.HMAC(data, None, hashfunc)
if not keylen:
keylen = mac.digest_size
def _pseudorandom(x, mac=mac):
h = mac.copy()
h.update(x)
return bytearray(h.digest())
buf = bytearray()
for block in range_type(1, -(-keylen // mac.digest_size) + 1):
rv = u = _pseudorandom(salt + _pack_int(block))
for i in range_type(iterations - 1):
u = _pseudorandom(bytes(u))
rv = bytearray(starmap(xor, izip(rv, u)))
buf.extend(rv)
return bytes(buf[:keylen])
def grouped_list(iterable, n):
"""
"s -> (s0,s1,s2,...sn-1), (sn,sn+1,sn+2,...s2n-1), (s2n,s2n+1,s2n+2,...s3n-1), ..."
例子:
for x, y in grouped(l, 2):
print "%d + %d = %d" % (x, y, x + y)
:param iterable: 迭代器
:param n: 间隔
:return: 组合
"""
return izip(*[iter(iterable)] * n)
def safe_str_cmp(a, b):
"""This function compares strings in somewhat constant time. This
requires that the length of at least one string is known in advance.
Returns `True` if the two strings are equal, or `False` if they are not.
.. versionadded:: 0.7
"""
if _builtin_safe_str_cmp is not None:
return _builtin_safe_str_cmp(text_type(a), text_type(b))
# Python2's version of that code dies when one is Unicode and the other is not
if len(a) != len(b):
return False
rv = 0
if isinstance(a, bytes) and isinstance(b, bytes) and not PY2:
for x, y in izip(a, b):
rv |= x ^ y
else:
for x, y in izip(a, b):
rv |= ord(x) ^ ord(y)
return rv == 0
def pbkdf2_bin(data, salt, iterations=DEFAULT_PBKDF2_ITERATIONS,
keylen=None, hashfunc=None):
"""Returns a binary digest for the PBKDF2 hash algorithm of `data`
with the given `salt`. It iterates `iterations` times and produces a
key of `keylen` bytes. By default, SHA-1 is used as hash function;
a different hashlib `hashfunc` can be provided.
.. versionadded:: 0.9
:param data: the data to derive.
:param salt: the salt for the derivation.
:param iterations: the number of iterations.
:param keylen: the length of the resulting key. If not provided
the digest size will be used.
:param hashfunc: the hash function to use. This can either be the
string name of a known hash function or a function
from the hashlib module. Defaults to sha1.
"""
if isinstance(hashfunc, string_types):
hashfunc = _hash_funcs[hashfunc]
elif not hashfunc:
hashfunc = hashlib.sha1
data = to_bytes(data)
salt = to_bytes(salt)
# If we're on Python with pbkdf2_hmac we can try to use it for
# compatible digests.
if _has_native_pbkdf2:
_test_hash = hashfunc()
if hasattr(_test_hash, 'name') and \
_test_hash.name in _hash_funcs:
return hashlib.pbkdf2_hmac(_test_hash.name,
data, salt, iterations,
keylen)
mac = hmac.HMAC(data, None, hashfunc)
if not keylen:
keylen = mac.digest_size
def _pseudorandom(x, mac=mac):
h = mac.copy()
h.update(x)
return bytearray(h.digest())
buf = bytearray()
for block in range_type(1, -(-keylen // mac.digest_size) + 1):
rv = u = _pseudorandom(salt + _pack_int(block))
for i in range_type(iterations - 1):
u = _pseudorandom(bytes(u))
rv = bytearray(starmap(xor, izip(rv, u)))
buf.extend(rv)
return bytes(buf[:keylen])
