Add google-endpoints to third_party/.

third_party/google-endpoints/Crypto/Random/random.py

+# -*- 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: