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#!/usr/bin/python
# -*- coding: ascii -*-
# Copyright (C) 2008 Dwayne C. Litzenberger <dlitz@dlitz.net>
#
# This file is part of paramiko.
#
# Paramiko is free software; you can redistribute it and/or modify it under the
# terms of the GNU Lesser General Public License as published by the Free
# Software Foundation; either version 2.1 of the License, or (at your option)
# any later version.
#
# Paramiko is distrubuted in the hope that it will be useful, but WITHOUT ANY
# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
# A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
# details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with Paramiko; if not, write to the Free Software Foundation, Inc.,
# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
# This is a runtime patch to fix a security issue in paramiko until it has
# officially been patched.
# For more information, see:
# http://www.lag.net/pipermail/paramiko/2008-January/000599.html
#
# -- David Guerizec <david@guerizec.net>
import sys
# Detect an OS random number source
osrandom_source = None
# Try os.urandom
if osrandom_source is None:
try:
from os import urandom
osrandom_source = "os.urandom"
except ImportError:
pass
# Try winrandom
if osrandom_source is None:
try:
from Crypto.Util import winrandom
osrandom_source = "winrandom"
except ImportError:
pass
# Try /dev/urandom
if osrandom_source is None:
try:
_dev_urandom = open("/dev/urandom", "rb", 0)
def urandom(bytes):
return _def_urandom.read(bytes)
osrandom_source = "urandom"
except (OSError, IOError):
pass
# Give up
if osrandom_source is None:
raise ImportError("Cannot find OS entropy source")
class BaseOSRandomPool(object):
def __init__(self, numbytes=160, cipher=None, hash=None):
pass
def stir(self, s=''):
# According to "Cryptanalysis of the Random Number Generator of the
# Windows Operating System", by Leo Dorrendorf and Zvi Gutterman
# and Benny Pinkas <http://eprint.iacr.org/2007/419>,
# CryptGenRandom only updates its internal state using kernel-provided
# random data every 128KiB of output.
if osrandom_source == 'winrandom' or sys.platform == 'win32':
self.get_bytes(128*1024) # discard 128 KiB of output
def randomize(self, N=0):
self.stir()
def add_event(self, s=None):
pass
class WinrandomOSRandomPool(BaseOSRandomPool):
def __init__(self, numbytes=160, cipher=None, hash=None):
self._wr = winrandom.new()
self.get_bytes = self._wr.get_bytes
self.randomize()
class UrandomOSRandomPool(BaseOSRandomPool):
def __init__(self, numbytes=160, cipher=None, hash=None):
self.get_bytes = urandom
self.randomize()
if osrandom_source in ("urandom", "os.urandom"):
OSRandomPool = UrandomOSRandomPool
elif osrandom_source == "winrandom":
OSRandomPool = WinrandomOSRandomPool
else:
raise AssertionError("Unrecognized osrandom_source %r" % (osrandom_source,))
# vim:set ts=4 sw=4 sts=4 expandtab:
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