/usr/share/pyshared/Crypto/Random/random.py is in python-crypto 2.4.1-1ubuntu0.1.
This file is owned by root:root, with mode 0o644.
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 | # -*- coding: utf-8 -*-
#
# Random/random.py : Strong alternative for the standard 'random' module
#
# Written in 2008 by Dwayne C. Litzenberger <dlitz@dlitz.net>
#
# ===================================================================
# The contents of this file are dedicated to the public domain. To
# the extent that dedication to the public domain is not available,
# everyone is granted a worldwide, perpetual, royalty-free,
# non-exclusive license to exercise all rights associated with the
# contents of this file for any purpose whatsoever.
# No rights are reserved.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
# BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
# ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
# CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.
# ===================================================================
"""A cryptographically strong version of Python's standard "random" module."""
__revision__ = "$Id$"
__all__ = ['StrongRandom', 'getrandbits', 'randrange', 'randint', 'choice', 'shuffle', 'sample']
from Crypto import Random
import sys
if sys.version_info[0] == 2 and sys.version_info[1] == 1:
from Crypto.Util.py21compat import *
class StrongRandom(object):
def __init__(self, rng=None, randfunc=None):
if randfunc is None and rng is None:
self._randfunc = None
elif randfunc is not None and rng is None:
self._randfunc = randfunc
elif randfunc is None and rng is not None:
self._randfunc = rng.read
else:
raise ValueError("Cannot specify both 'rng' and 'randfunc'")
def getrandbits(self, k):
"""Return a python long integer with k random bits."""
if self._randfunc is None:
self._randfunc = Random.new().read
mask = (1L << k) - 1
return mask & bytes_to_long(self._randfunc(ceil_div(k, 8)))
def randrange(self, *args):
"""randrange([start,] stop[, step]):
Return a randomly-selected element from range(start, stop, step)."""
if len(args) == 3:
(start, stop, step) = args
elif len(args) == 2:
(start, stop) = args
step = 1
elif len(args) == 1:
(stop,) = args
start = 0
step = 1
else:
raise TypeError("randrange expected at most 3 arguments, got %d" % (len(args),))
if (not isinstance(start, (int, long))
or not isinstance(stop, (int, long))
or not isinstance(step, (int, long))):
raise TypeError("randrange requires integer arguments")
if step == 0:
raise ValueError("randrange step argument must not be zero")
num_choices = ceil_div(stop - start, step)
if num_choices < 0:
num_choices = 0
if num_choices < 1:
raise ValueError("empty range for randrange(%r, %r, %r)" % (start, stop, step))
# Pick a random number in the range of possible numbers
r = num_choices
while r >= num_choices:
r = self.getrandbits(size(num_choices))
return start + (step * r)
def randint(self, a, b):
"""Return a random integer N such that a <= N <= b."""
if not isinstance(a, (int, long)) or not isinstance(b, (int, long)):
raise TypeError("randint requires integer arguments")
N = self.randrange(a, b+1)
assert a <= N <= b
return N
def choice(self, seq):
"""Return a random element from a (non-empty) sequence.
If the seqence is empty, raises IndexError.
"""
if len(seq) == 0:
raise IndexError("empty sequence")
return seq[self.randrange(len(seq))]
def shuffle(self, x):
"""Shuffle the sequence in place."""
# Make a (copy) of the list of objects we want to shuffle
items = list(x)
# Choose a random item (without replacement) until all the items have been
# chosen.
for i in xrange(len(x)):
x[i] = items.pop(self.randrange(len(items)))
def sample(self, population, k):
"""Return a k-length list of unique elements chosen from the population sequence."""
num_choices = len(population)
if k > num_choices:
raise ValueError("sample larger than population")
retval = []
selected = {} # we emulate a set using a dict here
for i in xrange(k):
r = None
while r is None or selected.has_key(r):
r = self.randrange(num_choices)
retval.append(population[r])
selected[r] = 1
return retval
_r = StrongRandom()
getrandbits = _r.getrandbits
randrange = _r.randrange
randint = _r.randint
choice = _r.choice
shuffle = _r.shuffle
sample = _r.sample
# These are at the bottom to avoid problems with recursive imports
from Crypto.Util.number import ceil_div, bytes_to_long, long_to_bytes, size
# vim:set ts=4 sw=4 sts=4 expandtab:
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